ASSESSING RENAL FUNCTION IN CHILDREN WITH MYELOMENINGOCELE

Because children with myelomeningocele (MM) are at increased risk of renal insufficiency, a simple method of estimating GFR from the plasma creatinine (PCr) and height would be useful. However, this estimate is predicated on a normal muscle mass and creatinine production for weight. Muscle mass may be diminished in children with paralysis. We therefore compared the estimate of GFR/1.73M2 from the formula 0.55 height (cm)÷ PCr with that determined with inulin in 14 children with MM ranging in age from 4-17 years. Seven had severe paralysis requiring wheelchair (WC) mobility. IVPs were abnormal in 9/14; 7/14 had inulin GFR < 80 ml/min/1.73M2. In 8 patients (57%) the estimated GFR averaged 85% higher than the inulin GFR. Of these 8 patients, 6 were WC-bound. In 5 patients (36%), there was close correlation between the two GFR methods, with an average difference of 11%. Only 1 of these was WC-bound. In 1 child, the estimated GFR was 64% lower than inulin GFR. All but 1 of the patients had PCr < 1 mg/dl. Our data suggest that an estimate of GFR determined from the serum creatinine and height in children with MM and significant paralysis is not reliable. This probably results from a diminished muscle mass and creatinine production per unit of body weight. Further studies are necessary to establish whether or not there is a reliable method for estimating GFR in this population.