Protocol-based metabolic evaluation in high-risk patients with renal stones in North India

CONTEXT: Renal calculus disease has a lifetime recurrence rate of 80%. Protocol-based metabolic evaluation in high-risk subjects for recurrent renal stones reveals abnormalities in a large subset of subjects. However, such information is not available in Indian subjects. AIMS: To evaluate the abnormalities by a protocol-based metabolic evaluation in patients at a high risk for recurrent renal stones. SETTINGS AND DESIGN: Prospective, academic tertiary care center. MATERIALS AND METHODS: Fifty North Indian patients (38 males and 12 females; mean age 38 ± 10.2 years) with recurrent or bilateral renal stones were evaluated. All subjects underwent a protocol-based evaluation involving estimation of serum total calcium, phosphorus, creatinine, albumin, iPTH, 25(OH)D(3), 1,25(OH)(2)D(3), and a calcium load test. Estimation of daily urinary excretion of volume, oxalate, calcium, uric acid, and citrate, and urinary acidification studies were performed. STATISTICAL ANALYSIS USED: Descriptive statistics and t-test. RESULTS: An underlying disorder was detected in 48 (96%) patients. Almost half had two or more metabolic abnormalities. The metabolic abnormalities detected were: Hypercalciuria 26 (52%) patients, renal hypercalciuria 16 (32%), absorptive hypercalciuria 6 (12%), unclassified hypercalciuria 4 (8%), hyperoxaluria 27 (54%), hyperuricosuria 9 (18%), distal renal tubular acidosis 4 (8%; 2 complete and 2 partial), primary hyperparathyroidism 3 (6%), and hypocitraturia 14 (n=18, 77%). In two patients, the etiology could not be detected. CONCLUSIONS: Protocol-based metabolic evaluation reveals metabolic abnormalities in majority of patients with nephrolithiasis. The spectrums of metabolic abnormalities are different in Indian subjects as compared to the western population.