Original article
Evaluation of serum calcium and serum parathyroid levels in post-menopausal women with and without oral dryness Balwinder Singh1, Shambulingappa Pallagatti2, Ramandeep Singh Narang3, Kirandeep Kaur4, Soheyl Sheikh2, Adesh Manchanda3 and Gagandeep Arora2 1
Department of Oral Medicine and Radiology, SGRD Institute of Dental Sciences & Research, Amritsar, India; 2Department of Oral Medicine and Radiology, M.M. College of Dental Sciences and Research, Mullana, Ambala, India; 3Department of Oral & Maxillofacial Pathology, SGRD Institute of Dental Sciences and Research, Amritsar, India; 4Department of Oral & Maxillofacial Surgery, SGRD Institute of Dental Sciences & Research, Amritsar, India
Gerodontology 2014; doi:10.1111/ger.12148 Evaluation of serum calcium and serum parathyroid levels in post-menopausal women with and without oral dryness Objective: The primary objective of this study was to estimate and secondary objective was to compare the serum calcium levels and serum parathyroid hormone (PTH) levels in post-menopausal women with and without oral dryness (OD). Materials and Methods: A case–control study was carried out on 80 selected post-menopausal women. Salivary flow was assessed by flow rate; serum calcium concentrations were assessed through Semi Autoanalyzer by Arsenazo III reaction. The serum PTH concentration was measured by the enzyme-linked immunosorbent assay. Severity of OD was assessed by a questionnaire through which the xerostomia inventory (XI) score could be measured. Statistical analysis of Student’s t-test, Mann– Whitney test and Pearson’s correlation was used. Results: There was a significant difference in mean values of both serum PTH concentration and XI score in post-menopausal women with/without OD (p < 0.001). No statistically significant difference (p = 0.354) was found in salivary flow rate and serum calcium levels in post-menopausal women in both groups. A positive correlation was found between the serum PTH and XI score in both case and control groups (p < 0.05). Conclusion: Severity of oral dryness in post-menopausal women is associated with the high levels of serum PTH. However, the correlation of severity of OD with serum calcium could not be established. Keywords: oral dryness, post-menopausal, osteoporosis, menopause, calcium, xerostomia. Accepted 1 August 2014
Introduction Menopause is the cessation of menstruation due to decrease in the oestrogen levels in the body. The physiological changes associated with menopause cause women to suffer some uncomfortable symptoms which include hot flashes, night sweats and vaginal dryness. In addition, oestrogen deprivation arising from menopause in association with age-related factors disproportionately increases the risk of developing cardiovascular disease, osteoporosis, Alzheimer’s disease and certain oral diseases1,2. Dental professional’s major concern is that the decrease of oestrogen level leads to oral symptoms
such as oral dryness and burning sensation in oral cavity, which are unrelated to salivary flow1,3. Oral dryness feeling is a major complaint for many elderly individuals; it is a subjective feeling and does not reflect a dry mouth in upto onethird of cases. It is associated with unpleasant feeling in the mouth and throat. It has been observed that dry mouth may exist in the presence of apparently sufficient amount of saliva. The prevalence of oral symptoms was found to be significantly greater in menopausal women at 43% than in pre-menopausal females at 6%4. Also, menopause-induced osteoporosis may lead to loss of alveolar bone height. Among few other oral disorders reported related to decrease in the
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
1
2
B. Singh et al.
level of oestrogen are lichen planus, benign mucosal pemphigoid, Sjogren’s syndrome, bad or altered taste, viscous saliva and senile atrophic gingivitis4. The relationship between oral dryness and calcium level has already been well established in post-menopausal women with oral dryness, and it has been found that mean concentration of stimulated whole saliva calcium is significantly higher in patients with oral dryness feeling3. Calcium is of much biological importance. Parathyroid hormone (PTH), calcitonin and vitamin D are concerned with its regulation. Calcium plays an indispensable part in physiological processes like mineralisation of the skeletal system and teeth, control of excitability of membranes of nerve and transmission of nerve impulses, activation of enzymes, secretion of hormones, synthesis of DNA and many more. The deficiency of calcium causes osteoporosis which is a painful and crippling disease affecting 1 in 3 women5. PTH is an important hormone in calcium turnover. Its main function is maintaining the calcium level in extracellular fluid. Secretion of PTH is stimulated by hypocalcaemia and suppressed by hypercalcaemia. The parathyroid glands can also suffer alterations due to decreased level of oestrogen. Due to this, the glands occasionally become hyperactive, thereby contributing to mobilisation of calcium and phosphorus deposits in osteoporosis6. As excessive salivary calcium was found in post-menopausal women with oral dryness, PTH which regulates calcium turnover will be evaluated in this study7. Subsequently, the purpose of this study was to compare the level of serum parathyroid and serum calcium level in post-menopausal women with and without oral dryness and to correlate its level with severity of oral dryness.
Materials and methods The study protocol was approved by the ethical committee of MM University, Ambala, India. This clinical study consisted of 80 post-menopausal women aged between 45 and 75 years who reported to the Department of Oral Diagnosis. Written informed consent was obtained, and the participants were subjected to a detailed case history. Inclusion criteria consisted of those postmenopausal women in whom a menstrual cycle had not occurred for at least 24 months3 and were not on any kind of medication at the time of the study. Participants with systemic diseases such as Sjogren’s syndrome, oral candidiasis,
diabetes and patients with poor oral hygiene and periodontitis were excluded from this study. Patients with poor oral hygiene and periodontitis were eliminated by intraoral clinical examination, showing periodontal pocket depths more than 3 mm in multiple sites. A questionnaire comprising of 10 questions was prepared with a list of symptoms related to xerostomia (Table 1)8. Forty participants who answered affirmatively to at least one of the questions related to xerostomia formed the case group; in fact, all the participants in the case group answered affirmatively to at least three of the questions. Forty participants who did not answer affirmatively to any of these questions in Table 1 formed the control group. The control group participants in this study constituted of participants with routine dental examination and superficial caries, and patients for complete dentures who voluntarily agreed to participate in the study. Each participant was then given another questionnaire, so that the severity of xerostomia could be assessed (Table 2)9. The xerostomia inventory (XI) score was determined as the severity of dry mouth feeling. The scores of responses were added to provide a XI score for each individual. The minimum possible score was 11, and the maximum possible score was 55 for each individual. Saliva collection Whole stimulated saliva was collected under resting condition in a quiet room between 8 am and 11 am at least 6 h after last intake of food or drink. Participants were asked to chew a standard 1-g piece of paraffin wax. Thereafter, whole saliva, stimulated by the same piece of paraffin, was Table 1 Questionnaire used for selection of subjects with oral dryness feeling7. 1. Does your mouth feel dry when eating a meal? 2. Do you have difficulties swallowing any foods? 3. Do you need to sip liquids to aid in swallowing dry foods? 4. Does the amount of saliva seem to be reduced in your mouth most of the time? 5. Does your mouth feel dry at night or on awakening? 6. Does your mouth feel dry during the day time? 7. Do you use gum or candy to relieve oral dryness? 8. Do you usually wake up thirsty at night? 9. Do you have problems in tasting food? 10. Does your tongue burn?
Y/N Y/N Y/N Y/N Y/N Y/N Y/N Y/N Y/N Y/N
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
Oral dryness with serum parathyroid and serum calcium
Table 2 The xerostomia inventory8. 1. I sip liquids to help swallow food. 2. My mouth feels dry when eating a meal. 3. I get up at night to drink. 4. My mouth feels dry. 5. I have difficulty in eating dry foods. 6. I suck sweets or cough lollies to relieve dry mouth. 7. I have difficulties swallowing certain foods. 8. The skin of my face feels dry. 9. My eyes feel dry. 10. My lips feel dry. 11. The inside of my nose feels dry. Response options: never (scoring 1), hardly (2), occasionally (3), fairly often (4), very often (5)
collected in about 5 min into a dry, deionised and sterilised plastic container which has markings from 0 to 20 ml. The flow rate was calculated in ml/min. Serum collection The participants’ blood was taken from anticubital fossa by venipuncture under aseptic condition using a 5-ml sterile, disposable syringe and a 24gauge needle, and 2.5 ml blood was drawn. The collected blood was transferred to sterile blood collecting tube. This was centrifuged at 447 g for five minutes, and the serum was separated and was stored at 20°C for later evaluation. Biochemical analysis Serum calcium levels were assessed colorimetrically by Arsenazo III reaction with Liquix Calcium Kit (Erba) and Semi Autoanalyser (Spectra Lab, Navi Mumbai, India). Arsenazo III combines with calcium ions at pH 6.75 to form a coloured chromophore, the absorbance of which is measured by semi-autoanalysers and is proportional to calcium concentration. Arsenazo III has a high affinity for calcium ions and shows no interference from other cations. PTH levels were assessed by enzyme-linked immunosorbent assay (ELISA) method by Parathyroid kit (Biomerica, Irvine, CA, USA) and ELISA Reader (Mind Ray). The kit contains two different goat polyclonal antibodies to human PTH. Calibrators, controls and participants samples were simultaneously incubated with the enzymelabelled antibody and a biotin-coupled antibody in a streptavidin-coated microplate well. At the end of the assay incubation, unbound components were washed to remove them and the enzyme
3
bound to the solid phase component is incubated with the substrate, tetramethylbenzidine. This converts the colour to yellow, and the intensity of the yellow colour is directly proportional to the concentration of intact PTH in the sample. Statistical analysis The data collected were first visualised to confirm their normal distribution. The resulting data were analysed using SPSS version 10 (IBM Developers, Armonl, New York, USA) and Epi-Info 6.04 software (CDC, Atlanta, Georgia, USA). Following this, descriptive statistics including mean values, standard deviations, 95% confidence interval and interquartile ranges (25th and 75th percentiles) were calculated for each variable. Two-tailed Student’s unpaired ‘t’-test and Mann–Whitney test were used to determine whether significant differences exist between means of two sets of observations (case and control group). Pearson’s correlation was used to check whether correlation exists between XI score and serum components. p < 0.05 was considered to be statistically significant.
Results In this study, there was no statistically significant difference between the mean ages of case (62.4 3.84 years) and control (59.9 4.63 years) group (p > 0.05). Student’s t-test showed that there was no significant difference (p > 0.05) in stimulated whole salivary flow rate (ml/min) between the case group (0.77 ml/min) and the control group (0.81 ml/min) (Table 3). The mean and median values of stimulated whole serum calcium and serum PTH in both case and control groups were obtained and were put for statistical analysis. The mean value of serum PTH level was higher in the case group (49.37 pg/ dl 24.2, n = 40) in comparison with the control group (32.51 pg/dl 18.01, n = 40) with significant difference between the two (p < 0.001) (Table 3). The mean value of serum calcium level in the case group was 8.21 mg/dl 1.99, n = 40 and in the control group was 8.61 mg/dl 1.84, n = 40 with no significant difference between the two (p > 0.05) (Table 3). The mean value of XI score in the case group was 22.10 4.95, n = 40 and the control group was 12.9 2.2, n = 40, which showed a significant difference between the two (p < 0.001) (Table 3). Pearson’s correlation was performed to see whether relationship exists between serum PTH, serum calcium and XI score in both the groups. The
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
4
B. Singh et al.
Table 3 Comparison of the salivary flow, serum calcium level, serum parathyroid hormone level and xerostomia inventory score in the case and control group.
Variables N Salivary flow (ml/min) Serum parathyroid level (pg/ml) Serum calcium level (mg/dl) Xerostomia inventory score
Case group
Control group
40
40
Mean
SD
Mean
SD
p-value
0.77 49.3702 8.2103 22.10
0.17 24.2521 1.9942 4.95
0.81 32.5101 8.6103 12.90
0.22 18.0171 1.8410 2.02
> 0.05 < 0.001** 0.354 < 0.001**
**
Highly significant.
result showed that there is a statistically significant positive correlation between the XI score and serum parathyroid hormone level in both case and control group with a correlation coefficient of 0.348 (r = 0.348) in the case group and .341 (r = 0.341) in the control group. However, no such significant correlation was found between the XI score and serum calcium in both the groups with correlation coefficient of 0.141 (r = 0.141) in the case group and 0.068 (r = 0.068) in the control group (Table 4, Figs 1 and 2). Similarly, when the total patients were analysed to see the relationship between serum PTH and XI score, the results obtained showed that there is positive correlation between two aforementioned parameters with a correlation coeffi-
cient of 0.484 (r = 0.484) with a highly statistical significant difference (p < 0.001). No statistical significant difference was observed between XI score and serum calcium (p > 0.05) (Table 4).
Discussion Oral dryness and burning mouth are increasingly common problems in the ageing population. This has remained an enigma for the treating clinician, because visible pathological lesions or processes are usually not evident. Oral dryness might be due to undetermined qualitative changes in the salivary composition, an unbalance between the various salivary glands or changes in the mucosal sensory receptors10.
Table 4 Correlation of severity of oral dryness with serum calcium level and serum parathyroid hormone levels in case group, control group and total sample size.
Group Cases (n = 40)
Serum PTH Serum PTH Serum calcium
Control (n = 40)
Xerostomia inventory score Serum PTH Serum calcium
Total sample size (n = 80)
Xerostomia inventory score Serum PTH Serum calcium Xerostomia inventory Score
Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed)
1 0.309 0.052 0.348* 0.028 1 0.012 0.942 0.341* 0.031 1 0.212 0.059 0.484** 0.000
Serum calcium 0.309 0.052 1 0.141 0.386 0.012 0.942 1 0.068 0.676 0.212 0.059 1 0.032 0.775
Xerostomia inventory score 0.348* 0.028 0.141 0.386 1 0.341* 0.031 0.068 0.676 1 0.484** 0.000 0.032 0.775 1
PTH – parathyroid hormone,* significant **highly significant. © 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
Oral dryness with serum parathyroid and serum calcium
Figure 1 Showing correlation of xerostomia inventory score with serum parathyroid hormone in case group.
Figure 2 Showing correlation of xerostomia inventory score with serum parathyroid hormone in control group.
In the current study, the salivary flow in both the case and control group of participants was statistically not significant (p > 0.05), but both groups showed symptoms of oral dryness. The possible reasons for this could be that oral dryness is a subjective feeling and may vary from patient to patient. Elderly age, drugs and effect of hormonal imbalance on salivary composition, of which oestrogen is particularly known to have effect, could be the dependent factors. The composition of saliva is oestrogen dependent, and we have recently conducted a study that participants with oral dryness have a high level of salivary calcium concentration with an inverse correlation with serum oestrogen11. Moreover, oestrogen b
5
receptors are found in salivary glands, gingival layer and buccal mucosa, and oestrogen is known to modulate epithelium and is thought to affect oral epithelium maturation process; therefore, a lack of oestrogen may account for undetective atrophic epithelium. Together with these observations, it is suggested that oestrogen level along with other factors plays an important role in oral mucosa and salivary gland physiology. Previous studies have also shown that the level of oestrogen status affects the saliva composition3,12,13. Also, hormone replacement therapy reduced oral dryness resulting in improved oral well-being3,14,15. Also, hormonal replacement therapies have relieved the symptoms of oral discomfort10,16. In the present study, most of the participants in case group were post-menopausal women having the chief complaint of oral dryness. The participants were given a set of questionnaire regarding the symptoms related to oral dryness, and they were further analysed for the severity of oral dryness through another set of questionnaire. It was found that the severity of OD (XI score) was more in post-menopausal women of the case group, when compared with the control group (p < 0.001). Similar findings were seen in a study conducted by Wardrop et al.16 in an Australian population and Ben Aryenh et al.17 in an Iranian population who found a high prevalence of oral discomfort in post-menopausal women. The present study is the first study to be conducted in an Indian population with all the 80 participants abstaining from any systemic manifestation, and this is different from the study conducted by Ben Aryenh et al in an Iranian population whose study group included participants with general systemic alterations17. Low level of oestrogen in post-menopausal women with oral dryness may affect general calcium and their salivary concentrations3,11. As oestrogen induces calcium absorption in the intestine and precipitates it in bones, a decrease in oestrogen in post-menopausal women suppresses intestinal absorption of calcium resulting in reduced plasma calcium levels16. In the current study, the serum calcium levels of participants in both the groups were reduced as compared to the normal (9–11 mg/dl) serum calcium level. The reason for this may be that serum calcium is regulated by many factors which prevent its fall in blood. With oestrogen deficiency causing calcium level to oscillate downwards, it may cause PTH levels to go up, resulting in increased loss of calcium from bones into blood. So, it may be possible that elevated serum calcium in post-menopausal
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
6
B. Singh et al.
women is excreted in saliva or urine. These women may exhibit hypercalciuria and osteoporosis18,19. Similar findings were seen in study conducted by Agha Hosseini et al in an Iranian population who also found no significant difference in serum calcium levels in post-menopausal women with and without oral dryness18. Our studies showed that PTH levels were significantly higher in the post-menopausal women having oral dryness and positive correlation was seen between severity of oral dryness and PTH levels, indicating the possibility that alteration in serum PTH may be a cause in incidence of oral dryness. The possible mechanism for changes in PTH level is not very clear; however, it could be attributed due to various reasons. As PTH rises in response to hypocalcaemia, it will tend to restore eucalcaemia by reduced renal calcium excretion and by its stimulation of renal conversion of 25hydroxyvitamin D to 1,25-dihydroxyvitamin D. Increased PTH levels also increase intestinal calcium absorption and mobilisation of calcium and phosphorus deposits from bones and cause weakness of bones, thus making the patient prone to osteoporosis. Furthermore, oestrogens prevent osteoporosis by inhibiting stimulatory effects of certain cytokines on osteoclasts. Hence, menopausal women have been considered at risk for periodontitis because of osteoporosis of the alveolar bone.20–22 Similar findings were seen in relation to serum PTH levels in post-menopausal women with and without oral dryness in a study conducted by Agha Hosseini et al.18. In a study conducted by Khosla et al. in 199723, it was seen that oestrogen deficiency results in an increase in bone turnover in post-menopausal women with increase in PTH levels. The increase in serum parathyroid hormone can cause bone mineral density to be reduced. Severity of oral dryness has also been associated with decreasing bone mineral density. Agha Hosseini in 201124 concluded that there was a significant negative correlation between XI score and
References 1. Friedlander AH. The physiology, medical management and oral implications of menopause. J Am Dent Assoc 2002; 133 : 73–81. 2. Utian WH. The scientific basis for postmenopausal estrogen therapy: The management of specific symptoms and rationale for long-term practice. In: Beard R ed. The Meno-
bone mineral density in post-menopausal women, indicating that oral dryness severity was associated with decreasing bone mineral density. In the present study, a statistically significant positive correlation was found between XI score and serum parathyroid hormone level in both case and control group and in total number of participants. Similar finding was seen in the study conducted by Agha Hosseini in 200918. Hence, it can be hypothesised that PTH level and XI score seem to be affected by the levels of oestrogen in postmenopausal women. So, the maintenance of oestrogen level may prevent oral discomfort along with other systemic problems in post-menopausal women.
Conclusion This study highlights the emergence of oral dryness feeling in post-menopausal women in the present scenario as a possible indicator for serum PTH level, serum calcium level and their possible roles in maintaining bone integrity. This study stresses on the fact that good history and the presence of signs and symptoms of oral dryness should be considered as a warning sign for possible development of osteoporosis and should be considered as a risk factor in post-menopausal women. It is recommended to conduct similar studies on various populations taking greater sample size in longitudinal format for further confirmation to evaluate whether post-menopausal women with oral dryness suffer from osteoporosis.
Conflict of interest Nil.
Acknowledgements A special word of thanks to statistician Mrs. Kusum Chopra for all kind of help in preparing the result. The study was self-financed.
pause - A Guide to Current Research and Practice. MTP Press: Lancaster, 1976: 175–201. 3. Agha-Hosseini F, Mirzaii-Dizgah I, Moghaddam P, Akrad ZT. Stimulated whole salivary flow rate and composition in menopausal women with oral dryness feeling. Oral Dis 2007; 13: 320–3. 4. Borhan Mojabi K, Esfahani M, Jahani Hashemi H. Evaluation of
unstimulated salivary flow rate and oral symptoms in menopausal women. J Dent 2007; 4: 103– 106. 5. Iqbal MM. Osteoporosis: epidemiology, diagnosis, and treatment. South Med J 2000; 93: 2–18. 6. Perez-Lopez FR. Vitamin D and its implications for musculoskeletal health in women: An update. Maturitas 2007; 58 : 117–37.
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
Oral dryness with serum parathyroid and serum calcium 7. Singh B, Sheikh S, Pallagatti S, Kaur K, Sohi R. Evaluation of salivarycalcium and salivary parathyroid levels inpostmenopausal women with and without oral dryness. Contemp Clin Dent 2013; 4 : 488–92. 8. Torres SR, Peixoto CB, Caldas DM, Silva EB, Akiti T, Nucci M et al. Relationship between salivary flow rates and Candida counts in subjects with xerostomia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002; 93: 149–54. 9. Thomson WM, Williams SM. Further testing of the xerostomia inventory. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000; 89: 46–50. 10. Bhat S, Hegde S, Bharthi SD. Ganapathy. A study on evaluation of the effect of menopause on saliva and dental health. J Adv Dent Res 2010; 1: 33–6. 11. Forabosco A, Criscuolo M, Coukos G, Uccelli E, Weinstein R, Spinato S et al. Efficacy of hormone replacement therapy in postmenopausal women with oral discomfort. Oral Surg Oral Med Oral Pathol 1992; 73: 570–4. 12. Singh R, Pallagatti S, Sheikh S, Singh B, Arora G, Aggarwal A. Correlation of serum oestrogen with salivary calcium in post-menopausal women with and without oral dryness feeling. Gerodontology 2012; 29: 125–9. 13. Mirzaii-Dizgah I, Agha-Hosseini F. Stimulated and unstimulated sal-
14.
15.
16.
17.
18.
19.
20.
iva progesterone in menopausal women with oral dryness feeling. Clin Oral Investig 2011; 15: 859–62. Leimola-Virtanen R, Helenius H, Laine M. Hormone replacement therapy and some salivary antimicrobial factors in post and perimenopausal women. Maturitas 1997; 27: 145–51. Sewon L, Laine M, Karjalainen S, Leimola R, Hiidenkar T, Helenius H. The effect of hormone replacement therapy on salivary calcium concentration in menopausal women. Arch Oral Biol 2000; 45 : 201–6. Wardrop RW, Hailes J, Burger H, Reade PC. Oral discomfort at menopause. Oral Surg Oral Med Oral Pathol 1989; 67: 535–40. Ben Aryeh H, Gottlieb I, Ish-Shalom S, David A, Szargel H, Laufer D. Oral complaints related to menopause. Maturitas 1996; 24: 185–9. Agha-Hosseini F, Iraj MD, Arash M, Gholochaman Z. Serum & Stimulated whole saliva parathyroid hormone in menopausal women with oral dryness feeling. Oral Surg Oral Med Oral Pathol Oral Endol 2009; 107: 806–10. Sewon LA, Karjalainen SM, Soderling E, Lapinleimu H, Simell O. Association between salivay calcium and oral health. J Clin Periodontol 1998; 25: 915–9. Sneve M, Emaus N, Joakimsen RM, Jorde R. The association
21.
22.
23.
24.
7
between serum parathyroid hormone and bone mineral density, and the impact of smoking: the Tromso Study. Eur J Endocrinol 2008; 158 : 401–9. Slavkin HC. Building a better mousetrap: Toward an understanding of osteoporosis. J Am Dent Assoc 1993; 130: 1632–1636. Ganong WF. Review of Medical Physiology. Singapore: McGraw Hill, 2005: 395. Khosla S, Atkinson EJ, Melton LJ III, Riggs BL. Effects of age and estrogen status on serum parathyroid hormone levels and biochemical markers of bone turnover in women: a population-based study. J Clin Endocrinol Metab 1997; 82: 1522–7. Agha-Hosseini F, Mirzaii-Dizgah I, Sadat MM. Relationship of lumbar spine bone mineral density and oral dryness feeling in menopause. Menopause 2011; 18 : 625–8.
Correspondence to: Dr Balwinder Singh, Department of Oral Medicine and Radiology, SGRD Institute of Dental Sciences & Research, Amritsar, Punjab, India. Tel.: +91 9988220039 Fax: 0183-2385656 E-mail: dr.balwindersingh@ rediffmail.com
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
Evaluation of serum calcium and serum parathyroid levels in post-menopausal women with and without oral dryness Balwinder Singh1, Shambulingappa Pallagatti2, Ramandeep Singh Narang3, Kirandeep Kaur4, Soheyl Sheikh2, Adesh Manchanda3 and Gagandeep Arora2 1
Department of Oral Medicine and Radiology, SGRD Institute of Dental Sciences & Research, Amritsar, India; 2Department of Oral Medicine and Radiology, M.M. College of Dental Sciences and Research, Mullana, Ambala, India; 3Department of Oral & Maxillofacial Pathology, SGRD Institute of Dental Sciences and Research, Amritsar, India; 4Department of Oral & Maxillofacial Surgery, SGRD Institute of Dental Sciences & Research, Amritsar, India
Gerodontology 2014; doi:10.1111/ger.12148 Evaluation of serum calcium and serum parathyroid levels in post-menopausal women with and without oral dryness Objective: The primary objective of this study was to estimate and secondary objective was to compare the serum calcium levels and serum parathyroid hormone (PTH) levels in post-menopausal women with and without oral dryness (OD). Materials and Methods: A case–control study was carried out on 80 selected post-menopausal women. Salivary flow was assessed by flow rate; serum calcium concentrations were assessed through Semi Autoanalyzer by Arsenazo III reaction. The serum PTH concentration was measured by the enzyme-linked immunosorbent assay. Severity of OD was assessed by a questionnaire through which the xerostomia inventory (XI) score could be measured. Statistical analysis of Student’s t-test, Mann– Whitney test and Pearson’s correlation was used. Results: There was a significant difference in mean values of both serum PTH concentration and XI score in post-menopausal women with/without OD (p < 0.001). No statistically significant difference (p = 0.354) was found in salivary flow rate and serum calcium levels in post-menopausal women in both groups. A positive correlation was found between the serum PTH and XI score in both case and control groups (p < 0.05). Conclusion: Severity of oral dryness in post-menopausal women is associated with the high levels of serum PTH. However, the correlation of severity of OD with serum calcium could not be established. Keywords: oral dryness, post-menopausal, osteoporosis, menopause, calcium, xerostomia. Accepted 1 August 2014
Introduction Menopause is the cessation of menstruation due to decrease in the oestrogen levels in the body. The physiological changes associated with menopause cause women to suffer some uncomfortable symptoms which include hot flashes, night sweats and vaginal dryness. In addition, oestrogen deprivation arising from menopause in association with age-related factors disproportionately increases the risk of developing cardiovascular disease, osteoporosis, Alzheimer’s disease and certain oral diseases1,2. Dental professional’s major concern is that the decrease of oestrogen level leads to oral symptoms
such as oral dryness and burning sensation in oral cavity, which are unrelated to salivary flow1,3. Oral dryness feeling is a major complaint for many elderly individuals; it is a subjective feeling and does not reflect a dry mouth in upto onethird of cases. It is associated with unpleasant feeling in the mouth and throat. It has been observed that dry mouth may exist in the presence of apparently sufficient amount of saliva. The prevalence of oral symptoms was found to be significantly greater in menopausal women at 43% than in pre-menopausal females at 6%4. Also, menopause-induced osteoporosis may lead to loss of alveolar bone height. Among few other oral disorders reported related to decrease in the
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
1
2
B. Singh et al.
level of oestrogen are lichen planus, benign mucosal pemphigoid, Sjogren’s syndrome, bad or altered taste, viscous saliva and senile atrophic gingivitis4. The relationship between oral dryness and calcium level has already been well established in post-menopausal women with oral dryness, and it has been found that mean concentration of stimulated whole saliva calcium is significantly higher in patients with oral dryness feeling3. Calcium is of much biological importance. Parathyroid hormone (PTH), calcitonin and vitamin D are concerned with its regulation. Calcium plays an indispensable part in physiological processes like mineralisation of the skeletal system and teeth, control of excitability of membranes of nerve and transmission of nerve impulses, activation of enzymes, secretion of hormones, synthesis of DNA and many more. The deficiency of calcium causes osteoporosis which is a painful and crippling disease affecting 1 in 3 women5. PTH is an important hormone in calcium turnover. Its main function is maintaining the calcium level in extracellular fluid. Secretion of PTH is stimulated by hypocalcaemia and suppressed by hypercalcaemia. The parathyroid glands can also suffer alterations due to decreased level of oestrogen. Due to this, the glands occasionally become hyperactive, thereby contributing to mobilisation of calcium and phosphorus deposits in osteoporosis6. As excessive salivary calcium was found in post-menopausal women with oral dryness, PTH which regulates calcium turnover will be evaluated in this study7. Subsequently, the purpose of this study was to compare the level of serum parathyroid and serum calcium level in post-menopausal women with and without oral dryness and to correlate its level with severity of oral dryness.
Materials and methods The study protocol was approved by the ethical committee of MM University, Ambala, India. This clinical study consisted of 80 post-menopausal women aged between 45 and 75 years who reported to the Department of Oral Diagnosis. Written informed consent was obtained, and the participants were subjected to a detailed case history. Inclusion criteria consisted of those postmenopausal women in whom a menstrual cycle had not occurred for at least 24 months3 and were not on any kind of medication at the time of the study. Participants with systemic diseases such as Sjogren’s syndrome, oral candidiasis,
diabetes and patients with poor oral hygiene and periodontitis were excluded from this study. Patients with poor oral hygiene and periodontitis were eliminated by intraoral clinical examination, showing periodontal pocket depths more than 3 mm in multiple sites. A questionnaire comprising of 10 questions was prepared with a list of symptoms related to xerostomia (Table 1)8. Forty participants who answered affirmatively to at least one of the questions related to xerostomia formed the case group; in fact, all the participants in the case group answered affirmatively to at least three of the questions. Forty participants who did not answer affirmatively to any of these questions in Table 1 formed the control group. The control group participants in this study constituted of participants with routine dental examination and superficial caries, and patients for complete dentures who voluntarily agreed to participate in the study. Each participant was then given another questionnaire, so that the severity of xerostomia could be assessed (Table 2)9. The xerostomia inventory (XI) score was determined as the severity of dry mouth feeling. The scores of responses were added to provide a XI score for each individual. The minimum possible score was 11, and the maximum possible score was 55 for each individual. Saliva collection Whole stimulated saliva was collected under resting condition in a quiet room between 8 am and 11 am at least 6 h after last intake of food or drink. Participants were asked to chew a standard 1-g piece of paraffin wax. Thereafter, whole saliva, stimulated by the same piece of paraffin, was Table 1 Questionnaire used for selection of subjects with oral dryness feeling7. 1. Does your mouth feel dry when eating a meal? 2. Do you have difficulties swallowing any foods? 3. Do you need to sip liquids to aid in swallowing dry foods? 4. Does the amount of saliva seem to be reduced in your mouth most of the time? 5. Does your mouth feel dry at night or on awakening? 6. Does your mouth feel dry during the day time? 7. Do you use gum or candy to relieve oral dryness? 8. Do you usually wake up thirsty at night? 9. Do you have problems in tasting food? 10. Does your tongue burn?
Y/N Y/N Y/N Y/N Y/N Y/N Y/N Y/N Y/N Y/N
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
Oral dryness with serum parathyroid and serum calcium
Table 2 The xerostomia inventory8. 1. I sip liquids to help swallow food. 2. My mouth feels dry when eating a meal. 3. I get up at night to drink. 4. My mouth feels dry. 5. I have difficulty in eating dry foods. 6. I suck sweets or cough lollies to relieve dry mouth. 7. I have difficulties swallowing certain foods. 8. The skin of my face feels dry. 9. My eyes feel dry. 10. My lips feel dry. 11. The inside of my nose feels dry. Response options: never (scoring 1), hardly (2), occasionally (3), fairly often (4), very often (5)
collected in about 5 min into a dry, deionised and sterilised plastic container which has markings from 0 to 20 ml. The flow rate was calculated in ml/min. Serum collection The participants’ blood was taken from anticubital fossa by venipuncture under aseptic condition using a 5-ml sterile, disposable syringe and a 24gauge needle, and 2.5 ml blood was drawn. The collected blood was transferred to sterile blood collecting tube. This was centrifuged at 447 g for five minutes, and the serum was separated and was stored at 20°C for later evaluation. Biochemical analysis Serum calcium levels were assessed colorimetrically by Arsenazo III reaction with Liquix Calcium Kit (Erba) and Semi Autoanalyser (Spectra Lab, Navi Mumbai, India). Arsenazo III combines with calcium ions at pH 6.75 to form a coloured chromophore, the absorbance of which is measured by semi-autoanalysers and is proportional to calcium concentration. Arsenazo III has a high affinity for calcium ions and shows no interference from other cations. PTH levels were assessed by enzyme-linked immunosorbent assay (ELISA) method by Parathyroid kit (Biomerica, Irvine, CA, USA) and ELISA Reader (Mind Ray). The kit contains two different goat polyclonal antibodies to human PTH. Calibrators, controls and participants samples were simultaneously incubated with the enzymelabelled antibody and a biotin-coupled antibody in a streptavidin-coated microplate well. At the end of the assay incubation, unbound components were washed to remove them and the enzyme
3
bound to the solid phase component is incubated with the substrate, tetramethylbenzidine. This converts the colour to yellow, and the intensity of the yellow colour is directly proportional to the concentration of intact PTH in the sample. Statistical analysis The data collected were first visualised to confirm their normal distribution. The resulting data were analysed using SPSS version 10 (IBM Developers, Armonl, New York, USA) and Epi-Info 6.04 software (CDC, Atlanta, Georgia, USA). Following this, descriptive statistics including mean values, standard deviations, 95% confidence interval and interquartile ranges (25th and 75th percentiles) were calculated for each variable. Two-tailed Student’s unpaired ‘t’-test and Mann–Whitney test were used to determine whether significant differences exist between means of two sets of observations (case and control group). Pearson’s correlation was used to check whether correlation exists between XI score and serum components. p < 0.05 was considered to be statistically significant.
Results In this study, there was no statistically significant difference between the mean ages of case (62.4 3.84 years) and control (59.9 4.63 years) group (p > 0.05). Student’s t-test showed that there was no significant difference (p > 0.05) in stimulated whole salivary flow rate (ml/min) between the case group (0.77 ml/min) and the control group (0.81 ml/min) (Table 3). The mean and median values of stimulated whole serum calcium and serum PTH in both case and control groups were obtained and were put for statistical analysis. The mean value of serum PTH level was higher in the case group (49.37 pg/ dl 24.2, n = 40) in comparison with the control group (32.51 pg/dl 18.01, n = 40) with significant difference between the two (p < 0.001) (Table 3). The mean value of serum calcium level in the case group was 8.21 mg/dl 1.99, n = 40 and in the control group was 8.61 mg/dl 1.84, n = 40 with no significant difference between the two (p > 0.05) (Table 3). The mean value of XI score in the case group was 22.10 4.95, n = 40 and the control group was 12.9 2.2, n = 40, which showed a significant difference between the two (p < 0.001) (Table 3). Pearson’s correlation was performed to see whether relationship exists between serum PTH, serum calcium and XI score in both the groups. The
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
4
B. Singh et al.
Table 3 Comparison of the salivary flow, serum calcium level, serum parathyroid hormone level and xerostomia inventory score in the case and control group.
Variables N Salivary flow (ml/min) Serum parathyroid level (pg/ml) Serum calcium level (mg/dl) Xerostomia inventory score
Case group
Control group
40
40
Mean
SD
Mean
SD
p-value
0.77 49.3702 8.2103 22.10
0.17 24.2521 1.9942 4.95
0.81 32.5101 8.6103 12.90
0.22 18.0171 1.8410 2.02
> 0.05 < 0.001** 0.354 < 0.001**
**
Highly significant.
result showed that there is a statistically significant positive correlation between the XI score and serum parathyroid hormone level in both case and control group with a correlation coefficient of 0.348 (r = 0.348) in the case group and .341 (r = 0.341) in the control group. However, no such significant correlation was found between the XI score and serum calcium in both the groups with correlation coefficient of 0.141 (r = 0.141) in the case group and 0.068 (r = 0.068) in the control group (Table 4, Figs 1 and 2). Similarly, when the total patients were analysed to see the relationship between serum PTH and XI score, the results obtained showed that there is positive correlation between two aforementioned parameters with a correlation coeffi-
cient of 0.484 (r = 0.484) with a highly statistical significant difference (p < 0.001). No statistical significant difference was observed between XI score and serum calcium (p > 0.05) (Table 4).
Discussion Oral dryness and burning mouth are increasingly common problems in the ageing population. This has remained an enigma for the treating clinician, because visible pathological lesions or processes are usually not evident. Oral dryness might be due to undetermined qualitative changes in the salivary composition, an unbalance between the various salivary glands or changes in the mucosal sensory receptors10.
Table 4 Correlation of severity of oral dryness with serum calcium level and serum parathyroid hormone levels in case group, control group and total sample size.
Group Cases (n = 40)
Serum PTH Serum PTH Serum calcium
Control (n = 40)
Xerostomia inventory score Serum PTH Serum calcium
Total sample size (n = 80)
Xerostomia inventory score Serum PTH Serum calcium Xerostomia inventory Score
Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed) Pearson correlation Sig. (2-tailed)
1 0.309 0.052 0.348* 0.028 1 0.012 0.942 0.341* 0.031 1 0.212 0.059 0.484** 0.000
Serum calcium 0.309 0.052 1 0.141 0.386 0.012 0.942 1 0.068 0.676 0.212 0.059 1 0.032 0.775
Xerostomia inventory score 0.348* 0.028 0.141 0.386 1 0.341* 0.031 0.068 0.676 1 0.484** 0.000 0.032 0.775 1
PTH – parathyroid hormone,* significant **highly significant. © 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
Oral dryness with serum parathyroid and serum calcium
Figure 1 Showing correlation of xerostomia inventory score with serum parathyroid hormone in case group.
Figure 2 Showing correlation of xerostomia inventory score with serum parathyroid hormone in control group.
In the current study, the salivary flow in both the case and control group of participants was statistically not significant (p > 0.05), but both groups showed symptoms of oral dryness. The possible reasons for this could be that oral dryness is a subjective feeling and may vary from patient to patient. Elderly age, drugs and effect of hormonal imbalance on salivary composition, of which oestrogen is particularly known to have effect, could be the dependent factors. The composition of saliva is oestrogen dependent, and we have recently conducted a study that participants with oral dryness have a high level of salivary calcium concentration with an inverse correlation with serum oestrogen11. Moreover, oestrogen b
5
receptors are found in salivary glands, gingival layer and buccal mucosa, and oestrogen is known to modulate epithelium and is thought to affect oral epithelium maturation process; therefore, a lack of oestrogen may account for undetective atrophic epithelium. Together with these observations, it is suggested that oestrogen level along with other factors plays an important role in oral mucosa and salivary gland physiology. Previous studies have also shown that the level of oestrogen status affects the saliva composition3,12,13. Also, hormone replacement therapy reduced oral dryness resulting in improved oral well-being3,14,15. Also, hormonal replacement therapies have relieved the symptoms of oral discomfort10,16. In the present study, most of the participants in case group were post-menopausal women having the chief complaint of oral dryness. The participants were given a set of questionnaire regarding the symptoms related to oral dryness, and they were further analysed for the severity of oral dryness through another set of questionnaire. It was found that the severity of OD (XI score) was more in post-menopausal women of the case group, when compared with the control group (p < 0.001). Similar findings were seen in a study conducted by Wardrop et al.16 in an Australian population and Ben Aryenh et al.17 in an Iranian population who found a high prevalence of oral discomfort in post-menopausal women. The present study is the first study to be conducted in an Indian population with all the 80 participants abstaining from any systemic manifestation, and this is different from the study conducted by Ben Aryenh et al in an Iranian population whose study group included participants with general systemic alterations17. Low level of oestrogen in post-menopausal women with oral dryness may affect general calcium and their salivary concentrations3,11. As oestrogen induces calcium absorption in the intestine and precipitates it in bones, a decrease in oestrogen in post-menopausal women suppresses intestinal absorption of calcium resulting in reduced plasma calcium levels16. In the current study, the serum calcium levels of participants in both the groups were reduced as compared to the normal (9–11 mg/dl) serum calcium level. The reason for this may be that serum calcium is regulated by many factors which prevent its fall in blood. With oestrogen deficiency causing calcium level to oscillate downwards, it may cause PTH levels to go up, resulting in increased loss of calcium from bones into blood. So, it may be possible that elevated serum calcium in post-menopausal
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
6
B. Singh et al.
women is excreted in saliva or urine. These women may exhibit hypercalciuria and osteoporosis18,19. Similar findings were seen in study conducted by Agha Hosseini et al in an Iranian population who also found no significant difference in serum calcium levels in post-menopausal women with and without oral dryness18. Our studies showed that PTH levels were significantly higher in the post-menopausal women having oral dryness and positive correlation was seen between severity of oral dryness and PTH levels, indicating the possibility that alteration in serum PTH may be a cause in incidence of oral dryness. The possible mechanism for changes in PTH level is not very clear; however, it could be attributed due to various reasons. As PTH rises in response to hypocalcaemia, it will tend to restore eucalcaemia by reduced renal calcium excretion and by its stimulation of renal conversion of 25hydroxyvitamin D to 1,25-dihydroxyvitamin D. Increased PTH levels also increase intestinal calcium absorption and mobilisation of calcium and phosphorus deposits from bones and cause weakness of bones, thus making the patient prone to osteoporosis. Furthermore, oestrogens prevent osteoporosis by inhibiting stimulatory effects of certain cytokines on osteoclasts. Hence, menopausal women have been considered at risk for periodontitis because of osteoporosis of the alveolar bone.20–22 Similar findings were seen in relation to serum PTH levels in post-menopausal women with and without oral dryness in a study conducted by Agha Hosseini et al.18. In a study conducted by Khosla et al. in 199723, it was seen that oestrogen deficiency results in an increase in bone turnover in post-menopausal women with increase in PTH levels. The increase in serum parathyroid hormone can cause bone mineral density to be reduced. Severity of oral dryness has also been associated with decreasing bone mineral density. Agha Hosseini in 201124 concluded that there was a significant negative correlation between XI score and
References 1. Friedlander AH. The physiology, medical management and oral implications of menopause. J Am Dent Assoc 2002; 133 : 73–81. 2. Utian WH. The scientific basis for postmenopausal estrogen therapy: The management of specific symptoms and rationale for long-term practice. In: Beard R ed. The Meno-
bone mineral density in post-menopausal women, indicating that oral dryness severity was associated with decreasing bone mineral density. In the present study, a statistically significant positive correlation was found between XI score and serum parathyroid hormone level in both case and control group and in total number of participants. Similar finding was seen in the study conducted by Agha Hosseini in 200918. Hence, it can be hypothesised that PTH level and XI score seem to be affected by the levels of oestrogen in postmenopausal women. So, the maintenance of oestrogen level may prevent oral discomfort along with other systemic problems in post-menopausal women.
Conclusion This study highlights the emergence of oral dryness feeling in post-menopausal women in the present scenario as a possible indicator for serum PTH level, serum calcium level and their possible roles in maintaining bone integrity. This study stresses on the fact that good history and the presence of signs and symptoms of oral dryness should be considered as a warning sign for possible development of osteoporosis and should be considered as a risk factor in post-menopausal women. It is recommended to conduct similar studies on various populations taking greater sample size in longitudinal format for further confirmation to evaluate whether post-menopausal women with oral dryness suffer from osteoporosis.
Conflict of interest Nil.
Acknowledgements A special word of thanks to statistician Mrs. Kusum Chopra for all kind of help in preparing the result. The study was self-financed.
pause - A Guide to Current Research and Practice. MTP Press: Lancaster, 1976: 175–201. 3. Agha-Hosseini F, Mirzaii-Dizgah I, Moghaddam P, Akrad ZT. Stimulated whole salivary flow rate and composition in menopausal women with oral dryness feeling. Oral Dis 2007; 13: 320–3. 4. Borhan Mojabi K, Esfahani M, Jahani Hashemi H. Evaluation of
unstimulated salivary flow rate and oral symptoms in menopausal women. J Dent 2007; 4: 103– 106. 5. Iqbal MM. Osteoporosis: epidemiology, diagnosis, and treatment. South Med J 2000; 93: 2–18. 6. Perez-Lopez FR. Vitamin D and its implications for musculoskeletal health in women: An update. Maturitas 2007; 58 : 117–37.
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
Oral dryness with serum parathyroid and serum calcium 7. Singh B, Sheikh S, Pallagatti S, Kaur K, Sohi R. Evaluation of salivarycalcium and salivary parathyroid levels inpostmenopausal women with and without oral dryness. Contemp Clin Dent 2013; 4 : 488–92. 8. Torres SR, Peixoto CB, Caldas DM, Silva EB, Akiti T, Nucci M et al. Relationship between salivary flow rates and Candida counts in subjects with xerostomia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002; 93: 149–54. 9. Thomson WM, Williams SM. Further testing of the xerostomia inventory. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000; 89: 46–50. 10. Bhat S, Hegde S, Bharthi SD. Ganapathy. A study on evaluation of the effect of menopause on saliva and dental health. J Adv Dent Res 2010; 1: 33–6. 11. Forabosco A, Criscuolo M, Coukos G, Uccelli E, Weinstein R, Spinato S et al. Efficacy of hormone replacement therapy in postmenopausal women with oral discomfort. Oral Surg Oral Med Oral Pathol 1992; 73: 570–4. 12. Singh R, Pallagatti S, Sheikh S, Singh B, Arora G, Aggarwal A. Correlation of serum oestrogen with salivary calcium in post-menopausal women with and without oral dryness feeling. Gerodontology 2012; 29: 125–9. 13. Mirzaii-Dizgah I, Agha-Hosseini F. Stimulated and unstimulated sal-
14.
15.
16.
17.
18.
19.
20.
iva progesterone in menopausal women with oral dryness feeling. Clin Oral Investig 2011; 15: 859–62. Leimola-Virtanen R, Helenius H, Laine M. Hormone replacement therapy and some salivary antimicrobial factors in post and perimenopausal women. Maturitas 1997; 27: 145–51. Sewon L, Laine M, Karjalainen S, Leimola R, Hiidenkar T, Helenius H. The effect of hormone replacement therapy on salivary calcium concentration in menopausal women. Arch Oral Biol 2000; 45 : 201–6. Wardrop RW, Hailes J, Burger H, Reade PC. Oral discomfort at menopause. Oral Surg Oral Med Oral Pathol 1989; 67: 535–40. Ben Aryeh H, Gottlieb I, Ish-Shalom S, David A, Szargel H, Laufer D. Oral complaints related to menopause. Maturitas 1996; 24: 185–9. Agha-Hosseini F, Iraj MD, Arash M, Gholochaman Z. Serum & Stimulated whole saliva parathyroid hormone in menopausal women with oral dryness feeling. Oral Surg Oral Med Oral Pathol Oral Endol 2009; 107: 806–10. Sewon LA, Karjalainen SM, Soderling E, Lapinleimu H, Simell O. Association between salivay calcium and oral health. J Clin Periodontol 1998; 25: 915–9. Sneve M, Emaus N, Joakimsen RM, Jorde R. The association
21.
22.
23.
24.
7
between serum parathyroid hormone and bone mineral density, and the impact of smoking: the Tromso Study. Eur J Endocrinol 2008; 158 : 401–9. Slavkin HC. Building a better mousetrap: Toward an understanding of osteoporosis. J Am Dent Assoc 1993; 130: 1632–1636. Ganong WF. Review of Medical Physiology. Singapore: McGraw Hill, 2005: 395. Khosla S, Atkinson EJ, Melton LJ III, Riggs BL. Effects of age and estrogen status on serum parathyroid hormone levels and biochemical markers of bone turnover in women: a population-based study. J Clin Endocrinol Metab 1997; 82: 1522–7. Agha-Hosseini F, Mirzaii-Dizgah I, Sadat MM. Relationship of lumbar spine bone mineral density and oral dryness feeling in menopause. Menopause 2011; 18 : 625–8.
Correspondence to: Dr Balwinder Singh, Department of Oral Medicine and Radiology, SGRD Institute of Dental Sciences & Research, Amritsar, Punjab, India. Tel.: +91 9988220039 Fax: 0183-2385656 E-mail: dr.balwindersingh@ rediffmail.com
© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd
