, and presence of risk
factors for stone formation, additional studies are needed.
These are 24-hour urine for calcium, phosphorus, uric acid,
oxalate, citrate, and cystine. Investigations for special
clinical situations like hyperparathyroidism, gout, renal
tubular acidosis should also be included. The cause of
renal stones can be found in 80 - 90% of cases with
detailed metabolic and biochemical investigations5. An
aetiological study of nephrolithiasis in north Indian
children have shown that an underlying metabolic
disorder can be demonstrated in about 50% of such
children6.
One should try to distinguish between metabolic active
or inactive stones by clinical and laboratory investigations.
Metabolic active stones are those that have been formed
within the past year, grown on X-ray within the past year,
or resulted in passage of documented gravel. Otherwise,
they are considered metabolically inactive. Metabolically
active stone should undergo detailed metabolic
investigations. This helps in proper management of such patients and prevent recurrence of disease. Medical
prophylaxis is cost-effective in patients with metabolic
active stone disease