Am J Kidney Dis 2002 Feb;39(2):383-91

Calcium Research: Dosage of potassium citrate in the correction of urinary abnormalities in pediatric distal renal tubular acidosis patients.

Domrongkitchaiporn S, Khositseth S, Stitchantrakul W, Tapaneya-olarn W, Radinahamed P.

Department of Medicine, Division of Nephrology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. rasdr@mahidol.ac.th

Potassium citrate is an alkaline agent that has been recommended for the prevention of nephrolithiasis in distal renal tubular acidosis (RTA). Information on the effectiveness and the optimal dose of potassium citrate in the correction of urinary abnormalities in pediatric distal RTA is limited, however.

We conducted this study to determine the effectiveness and the optimal dose of potassium citrate for the correction of urinary abnormalities and the prevention of nephrolithiasis in children with distal RTA. Eight pediatric distal RTA patients participated in this study. The mean +/- SEM age was 9.7 +/- 1.2 years, and mean body weight was 29.1 +/- 4.7 kg.

After initial evaluation, all patients were treated with increasing dosages of potassium citrate starting from 2 mEq/kg/d in three divided doses. The dosage was increased progressively in a stepwise fashion every 2 months from 2 mEq/kg/d to 3 mEq/kg/d, then to 4 mEq/kg/d. Blood and 8-hour overnight urine samples were obtained at baseline and every 2 months before increasing the dosage of potassium citrate. Urinary saturations for calcium oxalate and calcium phosphate were estimated by using Tiselius's indices. The basal urinary

calcium-to-creatinine, phosphate-to-creatinine, and calcium-to-citrate ratios and urinary saturation for calcium oxalate and calcium phosphate were elevated significantly, whereas citrate-to-creatinine ratio was reduced significantly in distal RTA patients. These ratios were normalized gradually with the increasing dosage of potassium citrate. All the aforementioned abnormalities were normalized only after the dosage of potassium citrate was raised to 4 mEq/kg/d. The elevation in urinary saturation of calcium phosphate could not be normalized throughout the study, however.

These results suggest that 4 mEq/kg/d of potassium citrate supplement can correct successfully most of the urinary abnormalities and the elevated urinary saturation for calcium oxalate but not for calcium phosphate in children with distal RTA. Monitoring of urinary calcium-to-creatinine ratio or citrate-to-creatinine ratio is valuable to ensure adequate potassium citrate supplementation in this group of patients.