Pediatric reference ranges for glomerular filtration rate determined by a single injection of Tc-99m DTPA

Objectives Radionuclide glomerular filtration rate (GFR) is a well-validated method to assess renal function, but there are no well-established pediatric reference ranges. The aim of this study is to establish reference values in children and young adults.

Methods 190 reference subjects (median age 8y, range 1 months-25y) had GFR determination at Children’s Hospital from 2000 to 2008 including 175 patients undergoing pre-chemotherapy evaluation and 15 potential renal donors. GFR was determined with a single intravenous injection technique using ^99mTc-DTPA. Serial blood samples at 2, 3, and 4 h were used to calculate GFR based on a single compartment model. Data were analyzed by age group, corrected for body surface area (BSA), and normalized to a BSA of 1.73m². The 95% reference ranges were calculated as mean ± 2SD.

Results GFR increased with age, likely reflecting increased renal mass. In all groups age ≥1y, the lower limit of the reference range is >65ml/min/1.73m². The lower normalized GFR in subjects age<1y may reflect renal immaturity.

Conclusions Reference ranges for GFR determined with a single injection of ^99mTc-DTPA will be useful for the assessment of renal function in children and young adults, particularly in patients less than 1y of age.