Hyperfiltration evaluated by glomerular filtration rate at diagnosis in children with cancer

BACKGROUND: Renal glomerular filtration rate (GFR) of pediatric cancer patients at diagnosis has previously been investigated in a limited number of studies. PROCEDURE: GFR, measured by iohexol clearance, was prospectively investigated in 55 children over the age of 1 year with malignancies, (group A). Elevated GFR (>175 ml/min/1.73 m(2)) at diagnosis was found. To investigate if this finding was consistent, a second group of 76 children with malignancies was studied, (group B). As a method control for GFR obtained by iohexol clearance, group A and B together were compared to 298 pediatric patients without cancer, group C. RESULTS: GFR was elevated in 40/131 (31%) in Group A + B but only in 17/298 (6%) in Group C. GFR was significantly higher in children aged 1-5 in group A + B (47%) compared to group C (3%). Bone marrow involvement was significantly associated with higher GFR. Children without bone marrow involvement also hyperfiltrated more often than controls, but less often. Urea in urine was used as a marker of renal protein clearance in 14 patients in group A. A significant correlation between u-urea (mmol/L)/u-creatinine (mmol/L) and GFR was noted. CONCLUSIONS: Hyperfiltration is sometimes present in children with cancer at diagnosis. This may be related to increased amino acid turn over in patients with a large tumor burden. An elevated initial GFR in a child with cancer, which normalizes after chemotherapy may indicate chemotherapy-induced decreased renal function, but can be due to normalization of an initially high GFR.