Nephrolithiasis in premature infants.

The clinical records of ten premature infants with nephrolithiasis were reviewed. The probable mechanism of stone formation was hypercalciuria due to furosemide therapy (nine patients) and congenital hyperparathyroidism (one patient). The relatively high rates of urinary excretion of calcium from immature kidneys predisposed these neonates to the development of calcium stones. Renal calculi in neonates are complications of distinct, treatable conditions, and premature babies receiving furosemide treatment should be screened by ultrasonography for renal calcifications.