Renal tubular acidosis in childhood.

Nineteen children with clinical diagnoses of renal tubular acidosis were followed for periods ranging from 3 months to 20 years. Twelve patients had Type 1 renal tubular acidosis, five had Type 2, and two had Type 4. No sex predilection was found for any one of the types. Most patients had been diagnosed before 18 months of age, with failure to thrive the most common presentation. Tachypnea, polydipsia, polyuria, and vomiting were frequent symptoms. Some of these children had associated renal hypoplasia, vesicoureteral reflux, unilateral renal agenesis, glomerulocystic disease, adult polycystic kidney disease, and cyanotic congenital heart disease. Urinary anion gap may be useful for differential diagnosis of altered distal urinary acidification from other hyperchloremic metabolic acidosis. Furosemide test may need further investigation. Inability to raise urine to blood pCO2 gradient is helpful for diagnosis of Type 1 renal tubular acidosis. Hypokalemia, hypocalcemia, hypophosphatemia, decreased tubular reabsorption of phosphate, and hypercalciuria occurred in some patients. Complications included rickets in two, nephrocalcinosis in one, and episodic hematuria in one. There was relative bicarbonate wasting in children with Type 1 renal tubular acidosis, with a mean therapeutic bicarbonate requirement of 4.4 +/- 2.6 meq/kg/day. The mean bicarbonate dose for patients with Type 2 renal tubular acidosis was 8.3 +/- 2.6 meq/kg/day. Most children had good response to treatment with complete catch-up linear growth in 13, improved growth in 4, and continuing poor growth in 2. Two patients died during follow-up. Two other patients maintained normal growth without medication.