Progression of renal insufficiency in pediatric patients: estimation from serum creatinine

Progression of renal insufficiency was estimated from serial serum creatinine (SCr) determinations in 45 pediatric patients with SCr greater than 2 mg/dl. This was done by plotting the logarithm of SCr (log SCr) versus time or the reciprocal (l/SCr) versus time. Calculation of data by linear regression analysis was restricted to 38 of these patients where at least 4 sequential SCr determinations were available. In 24 patients, a similar straight line relationship was observed on both plots. The semilog plot appeared more suitable in 2, and the reciprocal plot in 7 instances. In 5 patients progression of renal insufficiency was clearly non-linear. In the majority (33 of 38) of pediatric patients, loss of renal function occurred thus at an exponential rate (log SCr) or at a constant rate (l/SCr). The mean rate of progression of chronic renal insufficiency, expressed as SCr doubling time on the semilog plot, was 2.4 months in 10 patients with acquired glomerular diseases, 17 months in 3 patients with cystinosis, 27.7 months in 5 patients with renal hypoplasia or dysplasia, and 21.8 months in 13 patients with urinary tract abnormalities.