Search

The increased excretions of lithogenic substances (calcium, oxalate and uric acid) are known to be significant risk factors in stone formation1. Twenty five stone formers (SF) and age-sex-matched healthy subjects were asked to collect 3 h urine samples over a 24 h period. These were analyzed for calcium, oxalate, and uric acid by routine procedures. Computer programs using the method of least squares were used to detect a circadian rhythm2.

Environmental factors such as diet, climate, geographical factors, and fluid intake have an important role in the etiology of urolithiasis (1). Circadian rhythmicity in the urinary volume and excretion of creatinine (Cr), oxalate (Ox), glycolic acid, phosphate (Pi), uric acid (UA), sodium, potassium, chloride, and 17-keto steroids have been reported in healthy adults. Cohorts of stone formers who belong to the same ethnic group, share the same food habits, and are exposed to similar climatic conditions may be equally susceptible to stone disease which, possibly, may be present in the form of subtle biochemical changes. The present study investigates the circadian fluctuations in stone formers and cohorts of stone formers in an endemic area in northwestern India.

Calculus formation occurs in urine supersaturated with Ca, oxalate (Ox), phosphate (Pi), and uric acid (UA) (1). The calculated degrees of supersaturation have been used to estimate risk factors for the probably formation of renal stones. Normal urine contains a variety of inhibitory substances which may prevent or retard the precipitation of these lithogenic substances in the urinary tract. These inhibitors include components like citrate, isocitrate, pyrophosphate, magnesium polyacidic peptides, and a variety of polyanionic compounds as well. The present study is concerned with the inhibitory activity (IA) and urinary excretion of lithogenic substances, and examines possible correlations between urinary UA levels and urinary inhibitory activity towards CaOx-monohydrate (COM) crystal growth.

Urinary citrate is a potent inhibitor of calcium-oxalate and calciumphosphate crystal formation. It also forms soluble complexes with calcium, thereby decreasing the calcium-specific ion activity and relative supersaturation of both calcium oxalate and calcium phosphate (1). The present investigation was performed, therefore, to study circadian variations in citrate excretion in patients suffering from calcium urolithiasis and in control subjects.