Original Paper Urol Int 1992;48:404-408

Departments of a Biochemistry and b Urology, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Key Words Pyrophosphate Urolithiasis Stone formers Renal calculi Diclofenac sodium

Urinary Excretion of Inorganic Pyrophosphate by Normal Subjects and Patients with Renal Calculi in North-Western India and the Effect of Diclofenac Sodium upon Urinary Excretion of Pyrophosphate in Stone Formers

Abstract 24 h urinary pyrophosphate excretion was studied in 20 normal healthy sub­ jects and 75 idiopathic stone formers from north-western regions of India. The mean 24-hour urinary excretion of pyrophosphate was significantly low in stone formers (50.67 ±2 . 1 6 pmol/24 h) as compared to that of normal sub­ jects (71.46 ± 5.46 |imol/24 h) (p < 0.01). Diclofenac sodium, a non-steroidal anti-inflammatory agent, was administered 50 mg thrice daily for 1 week to 18 stone formers and 24-hour urinary pyrophosphate excretion was studied before and after drug therapy. The 24-hour urinary excretion of pyrophos­ phate increased from 54.32 ± 21.40 to 78.31 ± 28.03 pmol subsequent to diclofenac sodium therapy (p < 0.01).

Introduction Urinary calcium stone formation results from en­ hanced supersaturation with crystal and stone-forming urinary constituents and a deficit in substances acting as inhibitors of processes such as nucleation of solid phase, its transformation to other phase and growth/aggregation of crystals of calcium oxalate/calcium phosphate. The inhibitory substances include various metal ions, amino acids, acid mucopolysaccharides, etc. The possible inhibi­ tory role of organic and inorganic pyrophosphate has attracted considerable attention in recent years; however, data reported on this issue are contradictory. The 24-hour

Received: December 12. 1990 Accepted after revision: May 27. 1991

urinary excretion of pyrophosphate reported by different workers is lower than normal [1-6] or normal [7-9], Moreover, most of these studies did not consider the spe­ cific influences of age and sex which are known to have a controlling influence on the excretion of various inhibi­ tors of lithogenesis [10]. Non-steroidal anti-inflammatory drugs (NSAID) present a new strategy in the treatment of calcium oxalate urolithiasis as they are known to decrease urinary calcium excretion [11-13]. However, the effect of such drugs upon urinary excretion of pyrophosphate, an important inhibi­ tor of urinary stone formation, has not been studied so far. In the present study the urinary excretion of pyro-

Dr. S. Vaidyanathan Department of Urology Postgraduate Institute of Medical Education and Research Chandigarh 160012 (India)

© 1992 S. Kargcr AG. Basel 0042-1138/92/0484-0404 $2.75/0

Downloaded by: King's College London 137.73.144.138 - 3/5/2018 11:23:01 PM

S. Sharma* S. Vaidyanathanb S.K. Thinda R. Natha

phosphate is determined in healthy subjects and stone patients to obtain direct evidence of the role of pyrophos­ phate in the causation of stones in north-western regions of India. Diclofenac sodium, an NSAID, was adminis­ tered to 18 randomly selected stone formers (50 mg t.i.d. for 1 week) to see its effect, if any, on urinary excretion of pyrophosphate.

Patients and Methodology

Fig. 1. 24-hour urinary excretion of pyrophosphate and ortho­ phosphate in normal subjects (□ ) and stone formers (H). Values are expressed as mean ± SEM.

Table 1. Urinary chemistry of normal subjects and stone formers Description

Normal subjects (n = 20)

Stone formers (n = 75)

Total volume, ml/24 h pH Calcium, mmol/24 h Phosphorus, mmol/24 h Uric acid, mmol/24 h Creatinine, mmol/24 h Oxalate, mmol/24 h

1,682.49 ±175.18 6.20 ±0.15 5.59±0.68 23.12 ±2.12 3.46 ±0.15 10.45 ±0.81 0.25 ±0.02

1,846.15± 125.65 5.84 ±0.07 5.91 ±0.27 23.82 ±0.71 3.50 ± 0.12 9.97 ±0.30 0.45 ±0.02***

Values are expressed as mean ± SEM. *** p < 0.001, as compared to normal subjects.

Statistical A nalysis Student’s t test was used for statistical analysis of the data.

stone formers exhibited significant hyperoxaluria (0.45 ± 0.02 mmol) as compared to 24-hour urinary levels of oxa­ late in normal subjects (0.25 ± 0.02 mmol) (p < 0.001).

Results

24-Hour Urinary Pyrophosphate Excretion The data on pyrophosphate and orthophosphate in 24hour urine specimens of stone formers and controls are presented in figure 1. The mean 24-hour urinary excre­ tion of pyrophosphate was significantly (p < 0.01) low­ ered in stone formers (50.67 ± 2 . 1 6 pmol/24h) as com­ pared to that of normal subjects (71.46 ± 4.95

Urine Chemistry in Stone Formers and Normal Subjects There was no significant difference in the 24-hour uri­ nary excretion of calcium, phosphorus, uric acid and cre­ atinine in stone formers and in controls (table 1). The

405

Downloaded by: King's College London 137.73.144.138 - 3/5/2018 11:23:01 PM

Seventy-five stone formers attending the Nehru Hospital of PGIMER, Chandigarh, and 20 normal healthy subjects were in­ cluded in the study. The control subjects, who were healthy adult volunteers, were thoroughly interrogated for a history of renal dis­ ease, and clinical examination was normal. Further, a plain X-ray abdomen was taken to exclude urinary tract stone. Urine analysis was normal in all these control subjects. Stone patients had idio­ pathic calcium stones and were not suffering from additional dis­ eases such as diabetes mellitus, gout or hyperparathyroidism and none had undergone a major surgical intervention except for those related to stone disease. All participants were on a normal home diet during the 24-hour urine collection. Two 24-hour urine samples were collected for baseline estimation of urinary pyrophosphate. Diclofenac sodium was then prescribed in a dose of 50 mg 3 times a day for 1 week to 18 randomly selected stone formers. All patients were on a normal home diet during 24-hour urine collection and had normal renal function as checked by serum creatinine levels. Two 24-hour urine samples were collected on the 7th and 8th day of drug therapy for estimation of pyrophosphate. Duplicate samples from 24-hour urine containing up to 30 pg pyrophosphate (usually 2-5 ml) were heated in a boiling water bath for 2 min immediately after collection to destroy the pyrophospha­ tase activity and were stored at -20 °C till further analysis. Inorganic pyrophosphate was determined on Dowex-50 anion exchange resin, mesh 100-200, chloride form [1,7]. Orthophosphate was eluted with 100 ml of 0.05 ArHCl and pyrophosphate was eluted with 1 ArHCl. Urinary calcium [13], oxalate [14], uric acid [15] and creatinine [ 16] were estimated by standard procedures. The calcium to creati­ nine ratio (mg/mg) in the urine specimens permits classification of the subjects into those with normocalciuria (ratio < 0.27) and idio­ pathic hypercalciuria (ratio > 0.27). The latter condition comprises subjects with renal hypercalciuria or absorptive hypercalciuria. All controls were normocalciuric.

Table 2. 24-hour urinary pyrophosphate and orthophosphate in normal subjects and stone formers of different age groups Description

Number

Pyrophosphate pmol/24 h

Orthophosphate mmol/24 h

Normal healthy subjects 20-40 years 40-60 years Stone formers 20-40 years 40-60 years

20 15 5 75 48 27

71.46 + 4.95 68.03 + 6.78 74.38 + 5.67 50.67 + 2.16** 46.52 + 2.79* 59.32 + 3.84

5.53 + 0.45 5.69 + 0.42 3.75 + 0.71 4.15 + 0.19 3.98 + 0.17 4.26 + 0.30

Values are expressed as mean ± SEM. * p < 0.05; ** p < 0.01, as compared with their respective normal subjects.

406

Effect o f Diclofenac Sodium on 24-Hour Pyrophosphate Excretion No adverse effects to diclofenac sodium therapy were observed in any of the patients. There was no significant change in the 24-hour urinary volume and creatinine excretion after treatment. Treatment of stone patients with diclofenac sodium increased the 24-hour pyrophos­ phate excretion significantly as compared to the pretreat­ ment group (fig. 4). The pyrophosphate excretion was 54.32 ± 21.40 pmol/24h pretreatment as compared to the postdiclofenac therapy value of 78.31 ± 28.03 gmol/24 h.

Discussion Urinary pyrophosphate excretion was evaluated in 20 normal healthy subjects and in 75 idiopathic stone form­ ers. While a significant (p < 0.01) decline in 24-hour pyrophosphate excretion was observed in stone formers in this study which tallied with the earlier reports [2, 17, 18], other investigators found no difference in pyrophos­ phate excretion between control and stone formers [8, 9, 19,20]. In healthy subjects urinary excretion of pyrophos­ phate upto 100 pmol/24 h has been reported [21 ]. Etiolog­ ical difference in stone incidence as well geographical variation in the climatic, dietary and socio-economic con­ ditions of the stone formers may explain the differences in pyrophosphate excretion. Chronological variations in the chemical composition of urinary calculi have been ob­ served [22], The factors determining the urinary excretion of pyrophosphate have not been fully understood as yet, but diet, age and sex appear to play important parts. In agreement with observations of Schwüle et al. [21], pyro-

Sharma/Vaidyanathan/Thind/Nath

24-Hour Urinary Pyrophosphate in Stone Formers

Downloaded by: King's College London 137.73.144.138 - 3/5/2018 11:23:01 PM

|imol/24 h), whereas 24-hour urinary excretion of ortho­ phosphate was similar in both groups. The 24-hour uri­ nary excretion of pyrophosphate in male stone formers (n= 51) was 54.6 ± 21.98 pmol, whereas, in the female stone formers (n = 22) the pyrophosphate excretion was comparatively low (46.2 ± 18.96 pmol) but non-signifi­ cant. In the healthy male subjects (n = 19), the 24-hour urinary excretion of pyrophosphate was 68.8 ± 19.66 pmol and in the single female control subject it was 70.84 pmol. In stone formers within the age group of 20-40 years (n = 48), urinary pyrophosphate was significantly lowered (p < 0.05) as compared with the normal subjects (n = 15) of a similar age group (table 2), whereas in the 40- to 60year age group, the 24-hour urinary pyrophosphate levels were similar in stone formers (n = 27) and normal subjects (n = 5). Also no signifient correlation was observed between age and 24-hour urinary excretion of pyrophos­ phate in both healthy subjects (r = +0.03) and stone form­ ers ( r = +0.086). Figure 2 depicts the 24-hour urinary excretion pattern in the different age groups of healthy males and stone forming males. No differences were noted in 24-hour urinary orthophosphate levels in stone formers and subjects of different age groups (table 2). Based on calcium to creatinine ratio, only 10 stone formers could be classed in the hypercalciuric range. However, these patients failed to reveal any significant difference in their pyrophosphate levels as compared to that of normal subjects (n = 20) (fig. 3). On the other hand, normocalciuirc as well as the combined normocalciuric + hypercalciuric groups of stone formers each revealed a statistically significant (p < 0.01) decrease in the pyro­ phosphate levels as compared to normal subjects and hypercalciurics.

(20)

calciuric calciuric calciuric (10) + (65) hyper-

calciuric (75)

phosphate excretion was found to vary significantly with age in stone patients. The data of healthy subjects and stone patients (table 2) indicate that with advancing age stones may develop even in the presence of higher excre­ tion of urinary pyrophosphate than seen in younger stone patients. From the results of in vitro studies using differ­ ent techniques the issue still is controversial [23-25]. Whatever may be the cause, it seems mandatory when studying urinary pyrophosphate that the age of the partic­ ipants be kept comparable if false results are to be avoided. Though an overall pyrophosphate deficit was observed (fig. 1), low urinary pyrophosphate appeared to be a spe­ cific feature of normocalciuric patients indicating that in such patients a generalised inhibitor should be of patho­ genic importance as urine is less saturated with calcium salts than that of idiopathic hypercalciuric patients. No study has been reported from north-western India on pyrophosphate excretion by healthy subjects and by stone formers so far. Diclofenac sodium, an NSAID has been presented as a new and existing therapeutic agent for management of urolithiasis. The present study revealed that diclofenac sodium increases urinary excretion of pyrophosphate in stone formers and the drug had no sig-

Fig. 3. 24-hour urinary excretion of pyrophosphate (PPi) in normal controls and stone formers (normocalciuric and hypercalciuric). Values are expressed as mean ± SEM.

i Mean i

±

: SD

(n = 18)

(n = 18)

Fig. 4. Effect of diclofenac sodium on 24-hour urinary' excretion of pyrophosphate in idiopathic stone formers.

407

Downloaded by: King's College London 137.73.144.138 - 3/5/2018 11:23:01 PM

Fig. 2. Urinary pyrophosphate excretion in 24-hour urine of younger (20-40 years old) and older (more than 40 years old) healthy (□ ) and stone former ( 0 ) males. Values are expressed as mean ± SEM. Values in parentheses indicate number of subjects.

nificant adverse effects in the dose of 50 mg t.i.d. Thus, this therapy may prove beneficial in reducing the risk of stone formation by virtue of its effect on inhibitor poten­ tial of urine. The effect of diclofenac sodium on pathomechanisms in the formation of calcium-oxalate stones is said to be due to the blockage of prostaglandin production by NSAlDs resulting in a favourable effect on the risk of thermodynamic calcium stone formation. An additional component of risk reduction might result from urodynamic changes in the pelvicalyceal system and/or the tubular system. This study indicates another mechanism.

namely increase in the drug-induced inhibitor potential of urine which could also contribute to the success reported in the treatment of calcium stone formers with NSAIDs by Brundig and Borner [11], Long-term clinical studies extending over a period of 2-3 years are needed to con­ firm its efficacy in the prevention of recurrences in patients with urolithiasis. However, this preliminary work definitely indicates its beneficial effects towards an increase of 24-hour pyrophosphate excretion in stone formers.

1 Robertson WG, Peacock M: Metabolic and biochemical risk factors in renal stone disease. Contrib Nephrol 1984;37:1-4. 2 Baumann JM. Wacker M; The direct measure­ ment of inhibitory capacity to crystal growth of calcium oxalate in undiluted urine and in other inhibitor containing solutions. Urol Res 1980; 8:171-175. 3 Fleisch H, Bisaz S: Mechanism of calcification: inhibitory role of pyrophosphate. Nature 1962; 195:911. 4 Russell RGG, Edwards NA, Hodgkinson A: Urinary pyrophosphate and urolithiasis. Lan­ cet 1964;9:1446. 5 Baumann JM, Bisaz S, Felix R. Fleisch H, Ganz U, Russell RGG: The role of inhibitors and other factors in the pathogenesis of recur­ rent calcium containing renal stones. Clin Sci Mol Med 1977;53:141-148. 6 Wilkstrom B, Danielson BG, Ljunghall S, McGuire M, Russell RGG: Urinary pyrophos­ phate excretion in renal stone formers with normal and impaired renal acidification. World J Urol 1983;1:150. 7 Singh DP, Teotia M, Teotia SP, Nath I'M: Uri­ nary pyrophosphate excretion in stone formers. Indian J Med Res 1985:82:341—345. 8 Russell RGG. Hodgkinson A: The urinary ex­ cretion of inorganic pyrophosphate by normal subjects and patients with renal calculus. Clin Sci 1966;31:51-62. 9 O'Brien MM. Uhlemann J, McIntosh HW: Urinary pyrophosphate in normal subjects and in stone formers. Can Med Assoc J 1967:96: 100.

408

10 Schwüle PO, Scholz D. Schwüle K, Leutschaft R. Goldberg I, Siegel A: Citrate in urine and serum and associated variables in subgroups of urolithiasis. Results from an outpatient stone clinic. Nephron 1982;31:194-202. 11 Brundig P, Borner RH: Clinical results in the treatment of therapy resistant calcium stone formers with nonsteroidal anti-inflammatory drugs. EurUrol 1987;13:49-56. 12 Colette C. Aquiore L, Mommier L. Mimrau A: The influence of indomethacin and possible role of prostaglandin on calcium renal excre­ tion. Renal Physiol 1982;5:68-75. 13 Trinder P: Calcium determination by precipi­ tation; in Wootton IDP (ed): Microanalysis in Medical Biochemistry. London, Churchill, 1960, p 176. 14 Hodgkinson A, Williams A: An improved colo­ rimetric procedure for urine oxalate. Clin Chim Acta 1972;36:127-132. 15 Henry RJ: Determination of uric acid by reac­ tion with alkaline phosphotungstate. in Henry RJ (ed): Clinical Chemistry: Principles and Techniques. New York, Harper & Row, 1967, p 278-283. 16 Natelson S: Urine creatinine determination us­ ing alkaline picrate method, in Microtechni­ ques of Clinical Chemistry. Springfield, Thomas, 1963, p 196. 17 McIntosh HW, Carruthers BM: Urinary excre­ tion of pyrophosphate in recurrent calcium stone formers. Clin Res 1965:13:136-140. 18 Bataille R. Lacour B. Roullet JB. Finet M. Gregoire J, Fievet P, Fournier A: Pyrophosphate excretion in various groups of calcium stone formers: Effect of a calcium restricted diet, in Schwüle PO, Smith LH, Robertson WG. Vahlensieck W (eds): Urolithiasis and Related Clinical Research. New York. Plenum Press. 1985, p 437-441.

19 Teotia SPS, Teotia M, Teotia NPS: Primary bladder stone disease in children - Crystallisa­ tion studies with special reference to urinary excretion of pyrophosphate. Indian J Pediatr 1974;41:293-298. 20 Ramavataram DVSS, Singh PP. Pendsc AK, Hada P: Role of pyrophosphate in calculogenesis, in Walker VR, Sutton RAL, Bertcameron EC, PakCYC, Robertson WG (eds): Urolithia­ sis. New York, Plenum Press, 1989, p 223— 224. 21 Schwille PO. Rumcnapf G, Wolfel G, Kohler R: Urinary pyrophosphate in patients with re­ current calcium urolithiasis and in healthy con­ trols: A re-evaluation. J Urol 1988;140:239— 245. 22 Thind SK, Sidhu H, Nath R, Malakondaiah GC, Vaidyanathan S: Chronological variation in chemical composition of urinary calculi be­ tween 1965-1968 and 1982-1986 in NorthWestern India. Trop Geogr Med 1988;40:338341. 23 Wilson JWL. Werness PG, Smith LH: Inhibi­ tors of crystal growth of hydroxyapatite: A con­ stant composition approach. J Urol 1985; 134: 1255-1258. 24 Hallson PC, Rose GA. Sulaiman S: Pyrophos­ phate does not influence calcium oxalate or cal­ cium phosphate crystal formation in concen­ trated whole human urine. Urol Res 1983:11: 151. 25 Robertson WG, Scurr DS: Modifiers of cal­ cium oxalate crystallisation found in urine. 1. Studies with a continuous crystalliscr using an artificial urine. J Urol 1986:135:1322-1336.

Sharma/Vaidyanathan/Thind/Nath

24-Hour Urinary Pyrophosphate in Stone Formers

Downloaded by: King's College London 137.73.144.138 - 3/5/2018 11:23:01 PM

References

Urinary excretion of inorganic pyrophosphate by normal subjects and patients with renal calculi in north-western India and the effect of diclofenac sodium upon urinary excretion of pyrophosphate in stone formers.

24 h urinary pyrophosphate excretion was studied in 20 normal healthy subjects and 75 idiopathic stone formers from north-western regions of India. Th...
845KB Sizes 0 Downloads 0 Views