Renal Tubular Acidosis in Children

Publisher Website
Google Scholar
Abstract
To delineate the spectrum of clinical expressions of distal, type 1 renal tubular acidosis in children and to update progress in diagnosis, therapy, and prognosis, the medical records of 14 girls and 10 boys, seen over a 7 year period, who met the following criteria, were examined: persistent urinary pH more than 6, net acid excretion less than 70 .mu.Eq/min/1.73 m2, simultaneous serum total CO2 less than 17.5 mEq/l, and normal or mild impairment of the glomerular filtration rate. The mean age at diagnosis was 8 months. The presenting signs and symptoms were failure to thrive (50%), vomiting and/or diarrhea (37.5%), dehydration (12.5%), and or feeding (8.3%). Mean values .+-. SD of serum calcium (9.8 .+-. 0.8 mg/dl), inorganic phosphate (5.6 .+-. 0.8 mg/dl), and alkaline phosphatase (222.6 .+-. 96.1 U/l) were normal. Hyperkalemia (serum potassium above 5.0 mEq/l) was present at diagnosis in 13 children. Type 4 renal tubular acids was ruled out by the inability to achieve a minimum urine pH. With a mean follow-up period of 28.1 .+-. 25.3 months, after alkali therapy at 3.3-3.5 mEq/kg/day had been administered for at least 12 months, the growth parameters improved as follows; the percentile weight (mean .+-. SD) increased from the initial 11.8 .+-. 7.5 to the final 27.6 .+-. 31.3 (p < 0.003), and the length/height percentile increased from 11.5 .+-. 7.3 to 29.7 .+-. 24.2 (p < 0.03). The relationship between urine calcium/creatinine ratio and serum total CO2 showed poor correlation. Follow-up after a minimal of 12 months of alkali therapy showed the serum creatinine values to be 0.45 .+-. 0.17 mg/dl (mean .+-. SD); these values match the 0.5 .+-. 0.3 mg/dl values obtained at the time of diagnosis (p > 0.05). Radiological examinations systematically obtained in 16 patients showed no nephrocalcinosis or nephrolithiasis. We conclude that, as previously shown in adult patients, hyperkalemia rather than hypokalemia is encountered in an important proportion of pediatric patients with type 1 renal tubular acidosis. Early diagnosis and adequate alkaline treatment result in improved growth with the complications of hypercalciuria.