Comparison of Tc-99 measurement of glomerular filtration rate vs. calculated creatinine clearance to assess renal function pretransplant in pediatric patients undergoing hematopoietic stem cell transplantation

We compared the results of Tc-99 evaluation of glomerular filtration rate (GFR) vs. the calculation of the creatinine clearance (CCrC) as a predictor for the development of renal insufficiency in pediatric patients following hematopoietic stem cell transplantation (HSCT). We reviewed 95 consecutive patients receiving autologous (n = 37) or allogeneic (n = 58) HSCT at Children's Memorial Hospital between January, 1995 and February, 1998. Diagnoses included leukemia (n = 43), solid tumor (n = 27), bone marrow failure syndrome (n = 12), non-malignant disease (n = 8), CNS tumors (n = 5) and immunodeficiency (n = 3). Tc-99 GFR was compared with a calculated creatinine clearance derived from the Schwartz formula (CCrC) prior to HSCT. These measures of renal function were compared with the patient's subsequent clinical course to determine if patients who developed renal insufficiency of sufficient magnitude as to require continuous veno-venous hemofiltration (CVVH) or dialysis, could have been identified. Overall comparison of the two methods of evaluation of renal function showed low correlation with values obtained by CCrC, which were consistently higher in most patients (r-value 0.01 in the regression analysis and a p = 0.08 95% CI -24.15 to 1.48). When stratified for age, correlation between the two methods was excellent only in children younger than 5 yr of age p = 0.02 95%, CI 0.032-0.49). Eleven patients required therapy with CVVH or dialysis but neither CCrC nor Tc-99 GFR prior to transplant predicted this event. Patients who received TBI were statistically more prone to develop renal insufficiency than those without TBI (p < 0.0001, 95% CI 0.25-0.008). Neither the Tc-99 GFR nor the CCrC was predictive of the development of renal insufficiency in HSCT patients as the majority of patients who required dialysis had normal Tc-99 GFR prior to transplant. The characteristics found in the patients who developed renal insufficiency and required dialysis include: the use of total body irradiation as part of the transplant-conditioning regimen (p < 0.0001) and the use of continuous infusion CSA (p = 0.04).