Metabolic abnormalities in acute renal failure, influence on nutritional management

Abstract

Recurrent renal stones occur in ± 7.5% of Caucasian men and ± 3% of all women. Even with increasing urbanisation, renal calculi are reported in less than 1% of black South African men and women. Four hundred recurrent stone formers were studied at the metabolic stone clinic using routine and special tests. The appropriate therapy for each subgroup is outlined and studies on various different treatments are presented. In addition, lithogenic risk factors were studied in normal black and white subjects and in black stone formers, in order to clarify the low incidence in the black population. Patients were classified according to dietary and metabolic lithogenic risk factors. 10% of stone formers had pure dietary factors. The percentage of stone formers in each of the various metabolic subgroups was as follows: Renal hypercalciuria 12%, Absorptive hypercalciuria 10%, Mild metabolic hyperoxaluria 20%, Hypocitraturia 50%. Successful therapy in terms of preventing further stone formation was reported using Indapamide, calcium carbonate and potassium citrate in renal hypercalciuria, mild metabolic hyperoxaluria and hypocitraturia respectively. Black volunteer subjects had significantly higher 24hr urinary sodium excretion and significantly lower 24 hr. urinary calcium, citrate and cystine excretion than white volunteer subjects. Twenty-four hours urinary values in black stone formers were found to be approaching those levels found in white. -------------------Correspondence and offprint requests to: A M Meyers, Chief Physician, Department of Medicine, Division of Nephrology, 7 York Road, Parktown, 2193, South Africa. As urbanisation occurs in the black population, the incidence of urolithiasis would be expected to increase. We conclude that a detailed metabolic work-up is essential in the elucidation of the various metabolic risk factors in so-called ―idiopathic‖ CaOx stone formers. It allows appropriate, specific and highly cost-effective therapy aimed at the prevention of recurrence.