Metabolic risk factors in patients with renal stones in KwaZulu Natal: an inter‐racial study (Asian and Whites)

OBJECTIVE To identify any differences between Whites and Indians in KwaZulu Natal province, South Africa, in the metabolic risk factors which predispose them to urinary stone formation. PATIENTS AND METHODS Urinary stone disease is often a manifestation of an underlying metabolic disorder in most patients. Intrinsic and extrinsic factors affect the susceptibility of an individual to develop urinary stones. Although South African‐born Indians and Whites in KwaZulu Natal share some of the same extrinsic factors, diet and genetic factors differ between the groups. In a study from April 1999 until April 2001, 140 patients were included who had a radiological diagnosis of renal calculi; they were evaluated metabolically using previously recommended methods. RESULTS All the patients had at least one identifiable metabolic risk factor; the prevalence of the common metabolic risk factors was similar in the two groups. The prevalence of complete renal tubular acidosis (type 1) was significantly higher in the Indian patients. The most common metabolic abnormalities were hypomagnesuria and hypocitraturia, followed by low urinary volume. Hypercalciuria was not significant in this population. While Indians had lower urine volumes than Whites, Whites had significantly higher urinary calcium excretion than Indians. CONCLUSION There were a few variations in the metabolic risk factors between Indians and Whites, and the differences could be attributed to genetic or dietary habits. The high incidence of renal tubular acidosis in Indian patients could explain the higher prevalence of urinary stone disease in this group than in other racial groups.