Citrate and recurrent idiopathic calcium urolithiasis. A longitudinal pilot study on the metabolic effects of oral potassium citrate administered over the short-, medium- and long-term medication of male stone patients

Abstract

In idiopathic recurrent calcium urolithiasis (RCU) in men (n = 37) the metabolic effects of oral tripotassium citrate (PC) were investigated in a longitudinal field study. The patients were either normo- (n = 22) or hypocitraturic (n = 15). Laboratory examinations were performed before, and after 3, 6, and more than 12 months of medication. Acceptance of PC was poor, mainly because of the salty taste of the tablet preparation chosen, and a number of participants dropped out of the study. In the remaining participants, compliance was acceptable when evaluated on the basis of urinary potassium and undesired side effects did not occur. In the short term (up to 3 months), PC evoked compensated metabolic alkalosis (pH and citrate in urine increased; blood gases remained normal), a drop in urinary calcium, together with increasing oxaluria, hydroxyapatite supersaturation, and calcium phosphate crystalluria. In the long term (greater than 12 months) PC urinary pH and citrate "dissociated", in that pH returned to pretreatment baseline values, whereas citrate stayed at high levels. In normocitraturics but not in hypocitraturics, urinary urea and sodium increased with PC. Hypocitraturics appeared to be less sensitive to the effects of PC, as reflected by the relatively small rise in urinary pH and citrate, and they maintained higher mean levels of indicators of bone metabolism (osteocalcin, alkaline phosphatase, hydroxyproline) despite continuous administration of PC. It was concluded that although the PC tablet preparation was effective it may not be an ideal anti-stone drug treatment in the long term and that, especially in hypocitraturics, the intrinsic metabolic defect of RCU may not be sufficiently well controlled.