Forty-five patients with recurrent renal stone were examined for distal renal tubular acidosis (dRTA) defects by acid challenge test (150mg ammonium chloride/kg body weight). Their 24-h urine samples were analysed for creatinine, calcium, oxalic acid, inorganic phosphorus, uric acid, magnesium and citric acid. One-hour urine samples before acid load and hourly samples for the 7 h following acid challenge test were collected and analysed for creatinine, calcium, citric acid, inorganic phosphorus, titratable acidity, and ammonium. The incidence of distal RTA defect was 22.2% in the patients examined. The major biochemical characteristics in RTA patients compared with patients without RTA were: (a) significantly higher urinary pH, (b) significantly lower excretion of citric acid, (c) no significant difference in calcium excretion and (d) a tendency toward lower titratable acidity and ammonium excretion.
Key words Recurrent stone formers " Renal tubular acidosis
In the Indian state of Rajasthan which has a population of over 35000000, recurrent idiopathic urinary tract calcium stone disease is a major health problem [-7, 8, 14, 18J. Although the cause of calcium stone formation is multifactorial and largely unknown, in