Failure to thrive in children with primary distal type renal tubular acidosis

Primary distal type renal tubular acidosis (RTA-type1) results from defects of distal renal tubules in urinary acidification. In attempt to evaluate the clinical features, growth and outcome of primary distal type RTA in Taiwan, we retrospectively studied 28 patients (16 males and 12 females) of primary distal type RTA in our hospital in the past 13 years. The mean age at diagnosis was 2 years and 6.8 months old. Hematuria was found in 5 out of 25 cases (20%). Nephrocalcinosis was found in 5 out of 21 cases (23.8%). The mean value of Uca/Ucr was 0.313±0.067 in those older than 2 years and 0.262±0.152 in those younger than 2 years. Rickets was suspected in only one child by radiologic study. At initial diagnosis, the mean bone age was delayed for 16 months. The older the patient was, the more delayed was the bone age. The mean value of height was -2.81 standard deviation score (SDS); the mean value of body weight was -2.44SDS; and the mean value of growth velocity in height was -2.62SDS. After alkali therapy given from 8.5 months to 5 years and 7 months, improvement was found in height up to -1.69SDS, in body weight up to -1.10SDS, and in height velocity up to 1.06SDS.