EFFECT OF ENALAPRIL ON PROTEINURIA, PHOSPHATURIA, AND CALCIURIA IN INSULIN-DEPENDENT DIABETES

Elevated urinary calcium and phosphate excretion have been observed in children with insulin-dependent diabetes mellitus (IDDM). This may be related to a defect in tubular reabsorption. It is well known that co nverting enzyme inhibition decreases microalbuminuria and may prevent or retard diabetic nephropathy. We investigated whether enalapril also improves the defect in calcium and phosphate reabsorption, We studied 16 children and young adults (age 12-21 years) with IDDM and persiste nt microalbuminuria before and during 12 weeks of enalapril treatment. Before treatment microalbuminuria, urinary calcium excretion, and fra ctional tubular phosphorus reabsorption (TPR) were 153+/-53 mu g/min, 5.5+/-0.9 mg/kg per day, and 71.4+/-3.6%, respectively. At the end of the 12th week, microalbuminuria had decreased to 20.3+/-7.9 mu g/min a nd calcium excretion to 3.3+/-0.4 mg/kg per day (P<0.01), while the TP R increased to 80.1+/-3.8% (NS). The renal threshold phosphate concent ration increased from 1.8+/-0.15 to 2.92+/-0.23 mg/dl (P<0.01). The fa sting serum,glucose and hemoglobin Al, levels did not change significa ntly during the study. Systolic and diastolic blood pressures were 120 .4+/-2.2/79.3+/-1.4 mm HE and 110.5+1.8/71.3+/-0.9 mm Hg before and af ter 12 weeks, respectively. We conclude that enalapril treatment impro ves not only microalbuminuria but also abnormal calcium and phosphate excretion in microalbuminuric children with IDDM.