CITRATE IN DAILY AND FASTING URINE - RESULTS OF CONTROLS, PATIENTS WITH RECURRENT IDIOPATHIC CALCIUM UROLITHIASIS, AND PRIMARY HYPER-PARATHYROIDISM

  • 1 January 1979
    • journal article
    • research article
    • Vol. 16  (6) , 457-462
Abstract
In 3 groups-patients with recurrent Ca urolithiasis (RCU), patients with primary hyperparathyroidism (pHPT) and healthy controls-citrate was measured enzymatically in 24 and in 2 h urine after an overnight fast. Citrate excretion per 24 h was significantly lower in RCU than in age and sex matched controls, whereas there was no significant difference in citrate excretion in urines from the 2-h morning collection. In pHPT citrate was also lower than in controls and fell within the range of RCU of comparable age. Both categories of urines (24 and 2 h) have in common the characteristic that the actual citrate concentration is lower by 50% in RCU and pHPT than in controls, mainly as a result of the higher urine volume. Correction of citrate for creatinine does not disclose further differences among the populations studied but conversely hampers exact interpretation of urinary citrate in the absence of strict separation of individuals according to sex and age. A low excretion and concentration of urinary citrate is detectable in Ca lithiasis and may contribute to a deficiency in inhibitory activity against nucleating processes in stone-forming urine. The differences in urinary citrate elicited in samples of 24 and 2 h morning urine are of unknown origin and merit further investigations.