Arch Gynecol Obstet (2015) 292:1–2 DOI 10.1007/s00404-015-3714-1
LETTER TO THE EDITOR
The effect of seasonal variations on vitamin D levels in pregnant women Fatma Beyazit1 • Yavuz Beyazit2
Received: 30 January 2015 / Accepted: 2 April 2015 / Published online: 16 April 2015 Ó Springer-Verlag Berlin Heidelberg 2015
Dear Editor, In a recent issue of the Archives of Gynecology and Obstetrics, Singla et al. [1] brought to our attention the role of vitamin D in preeclampsia and its complications. The authors state that women with preeclampsia had significantly lower vitamin D levels compared to normal women, which may play a role in the pathogenesis of preeclampsia. Although the report by Singla and colleagues is surely welcome for improving current knowledge of factors leading to preeclampsia that may endanger the mother’s health as well as her neonate, in our opinion, some points in their article require clarification and further discussion. First, recent available data suggest that seasonal variations in vitamin D production have a great impact on serum vitamin D levels, which necessitates seasonally adjusted thresholds individualized for different locations [2, 3]. Current literature also supports that serum vitamin D levels in winter are at the lowest level versus the summer and the spring [4]. Moreover, though there is the common belief that low serum vitamin D is negligible in populations living in sunlight-rich countries, seasonal variations in vitamin D levels have been widely reported even in subtropical locations with year-round sunny and warm weather [5]. In
this context, we think that the authors must take into account the role of seasonal variation on serum vitamin D levels, even though the results are presented from a country rich in sunlight. Second, it is uncertain from the present study whether serum vitamin D levels were measured as 25-OH vitamin D (inactive form) or 1,25-(OH)2 vitamin D (biologically active form). Although previous studies found both low serum levels of 25-OH vitamin D and 1,25-(OH)2 vitamin D in patients with preeclampsia compared to healthy pregnant women of the same gestational age, during normal pregnancy, maternal 1,25-(OH)2 vitamin D levels are found to be elevated [6, 7]. In humans, 25-OH vitamin D is the major storage form of vitamin D, so it can be measured in blood to estimate the overall vitamin D status [8]. In view of this data, it would be noteworthy for the authors to mention the exact form of vitamin D that they measured for the study interpretation. And finally one shortcoming of the present study is that no parathyroid hormone (PTH) levels of the study participants are available. Women with low serum vitamin D levels may develop secondary hyperparathyroidism, which is also associated with an increased risk of preeclampsia [9]. Conflict of interest
We declare that we have no conflict of interest.
This comment refers to the article available at doi:10.1007/s00404014-3550-8 and an author’s reply to this comment is available at doi:10.1007/s00404-015-3716-z. & Fatma Beyazit [email protected] 1
Department of Obstetrics and Gynecology, Canakkale State Hospital, Canakkale, Turkey
2
Department of Gastroenterology, Canakkale State Hospital, Canakkale, Turkey
References 1. Singla R, Gurung P, Aggarwal N, Dutta U, Kochhar R (2014) Relationship between preeclampsia and vitamin D deficiency: a case control study. Arch Gynecol Obstet. doi:10.1007/s00404-0143550-8 2. Gonza´lez-Parra E, Avila PJ, Mahillo-Ferna´ndez I, Lentisco C, Gracia C, Egido J et al (2012) High prevalence of winter
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Arch Gynecol Obstet (2015) 292:1–2 25-hydroxyvitamin D deficiency despite supplementation according to guidelines for hemodialysis patients. Clin Exp Nephrol 16:945–951 Bird ML, Hill KD, Robertson IK, Ball MJ, Pittaway J, Williams AD (2013) Serum [25(OH)D] status, ankle strength and activity show seasonal variation in older adults: relevance for winter falls in higher latitudes. Age Ageing 42:181–185 Heidari B, Haji Mirghassemi MB (2012) Seasonal variations in serum vitamin D according to age and sex. Caspian J Intern Med 3:535–540 Levis S, Gomez A, Jimenez C, Veras L, Ma F, Lai S, Hollis B, Roos BA (2005) Vitamin D deficiency and seasonal variation in an adult South Florida population. J Clin Endocrinol Metab 90:1557–1562 Tabesh M, Salehi-Abargouei A, Tabesh M, Esmaillzadeh A (2013) Maternal vitamin D status and risk of pre-eclampsia: a systematic review and meta-analysis. J Clin Endocrinol Metab 98:3165–3173
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7. Lechtermann C, Hauffa BP, Herrmann R, Schu¨ndeln MM, Gellhaus A, Schmidt M (2014) Maternal vitamin D status in preeclampsia: seasonal changes are not influenced by placental gene expression of vitamin D metabolizing enzymes. PLoS ONE 9:e105558 8. Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B (2006) Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr 84:18–28 9. Scholl TO, Chen X, Stein TP (2013) Vitamin D, secondary hyperparathyroidism, and preeclampsia. Am J Clin Nutr 98:787–793
LETTER TO THE EDITOR
The effect of seasonal variations on vitamin D levels in pregnant women Fatma Beyazit1 • Yavuz Beyazit2
Received: 30 January 2015 / Accepted: 2 April 2015 / Published online: 16 April 2015 Ó Springer-Verlag Berlin Heidelberg 2015
Dear Editor, In a recent issue of the Archives of Gynecology and Obstetrics, Singla et al. [1] brought to our attention the role of vitamin D in preeclampsia and its complications. The authors state that women with preeclampsia had significantly lower vitamin D levels compared to normal women, which may play a role in the pathogenesis of preeclampsia. Although the report by Singla and colleagues is surely welcome for improving current knowledge of factors leading to preeclampsia that may endanger the mother’s health as well as her neonate, in our opinion, some points in their article require clarification and further discussion. First, recent available data suggest that seasonal variations in vitamin D production have a great impact on serum vitamin D levels, which necessitates seasonally adjusted thresholds individualized for different locations [2, 3]. Current literature also supports that serum vitamin D levels in winter are at the lowest level versus the summer and the spring [4]. Moreover, though there is the common belief that low serum vitamin D is negligible in populations living in sunlight-rich countries, seasonal variations in vitamin D levels have been widely reported even in subtropical locations with year-round sunny and warm weather [5]. In
this context, we think that the authors must take into account the role of seasonal variation on serum vitamin D levels, even though the results are presented from a country rich in sunlight. Second, it is uncertain from the present study whether serum vitamin D levels were measured as 25-OH vitamin D (inactive form) or 1,25-(OH)2 vitamin D (biologically active form). Although previous studies found both low serum levels of 25-OH vitamin D and 1,25-(OH)2 vitamin D in patients with preeclampsia compared to healthy pregnant women of the same gestational age, during normal pregnancy, maternal 1,25-(OH)2 vitamin D levels are found to be elevated [6, 7]. In humans, 25-OH vitamin D is the major storage form of vitamin D, so it can be measured in blood to estimate the overall vitamin D status [8]. In view of this data, it would be noteworthy for the authors to mention the exact form of vitamin D that they measured for the study interpretation. And finally one shortcoming of the present study is that no parathyroid hormone (PTH) levels of the study participants are available. Women with low serum vitamin D levels may develop secondary hyperparathyroidism, which is also associated with an increased risk of preeclampsia [9]. Conflict of interest
We declare that we have no conflict of interest.
This comment refers to the article available at doi:10.1007/s00404014-3550-8 and an author’s reply to this comment is available at doi:10.1007/s00404-015-3716-z. & Fatma Beyazit [email protected] 1
Department of Obstetrics and Gynecology, Canakkale State Hospital, Canakkale, Turkey
2
Department of Gastroenterology, Canakkale State Hospital, Canakkale, Turkey
References 1. Singla R, Gurung P, Aggarwal N, Dutta U, Kochhar R (2014) Relationship between preeclampsia and vitamin D deficiency: a case control study. Arch Gynecol Obstet. doi:10.1007/s00404-0143550-8 2. Gonza´lez-Parra E, Avila PJ, Mahillo-Ferna´ndez I, Lentisco C, Gracia C, Egido J et al (2012) High prevalence of winter
123
2
3.
4.
5.
6.
Arch Gynecol Obstet (2015) 292:1–2 25-hydroxyvitamin D deficiency despite supplementation according to guidelines for hemodialysis patients. Clin Exp Nephrol 16:945–951 Bird ML, Hill KD, Robertson IK, Ball MJ, Pittaway J, Williams AD (2013) Serum [25(OH)D] status, ankle strength and activity show seasonal variation in older adults: relevance for winter falls in higher latitudes. Age Ageing 42:181–185 Heidari B, Haji Mirghassemi MB (2012) Seasonal variations in serum vitamin D according to age and sex. Caspian J Intern Med 3:535–540 Levis S, Gomez A, Jimenez C, Veras L, Ma F, Lai S, Hollis B, Roos BA (2005) Vitamin D deficiency and seasonal variation in an adult South Florida population. J Clin Endocrinol Metab 90:1557–1562 Tabesh M, Salehi-Abargouei A, Tabesh M, Esmaillzadeh A (2013) Maternal vitamin D status and risk of pre-eclampsia: a systematic review and meta-analysis. J Clin Endocrinol Metab 98:3165–3173
123
7. Lechtermann C, Hauffa BP, Herrmann R, Schu¨ndeln MM, Gellhaus A, Schmidt M (2014) Maternal vitamin D status in preeclampsia: seasonal changes are not influenced by placental gene expression of vitamin D metabolizing enzymes. PLoS ONE 9:e105558 8. Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B (2006) Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr 84:18–28 9. Scholl TO, Chen X, Stein TP (2013) Vitamin D, secondary hyperparathyroidism, and preeclampsia. Am J Clin Nutr 98:787–793
