Pediatric Reference Ranges for Glomerular Filtration Rate Determined by a Single Injection of 99mTc-DTPA.

Determination of glomerular filtration rate (GFR) with 99mTc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA) is a validated method to assess renal function, but there are no well-established pediatric reference ranges for GFR. The aim of this study was to establish reference GFRs in children and young adults.

Methods

GFR was calculated for 235 reference subjects (median age, 4.86 y; range, 20 d to 24.8 y) using 99mTc-DTPA at Boston Children's Hospital between 2000 and 2020. This included 220 patients for prechemotherapy evaluation and 15 potential kidney donors. GFR was determined using a single-compartment model after a single intravenous injection technique and serial blood sampling at 2, 3, and 4 h. Data were analyzed by age, corrected for body surface area, and normalized to a body surface area of 1.73 m2 The 95% reference ranges were calculated as mean ± 1.96 SD.

Results

GFR increased with age, likely reflecting increased functional renal mass. Lower normalized GFR in children younger than 1 y may reflect renal immaturity.

Conclusion

The use of a single injection of 99mTc-DTPA revealed that GFR increases with age, likely reflecting increased renal mass. Further, in patients younger than 1 y, GFR rapidly increases initially, with a subsequent more gradual increase, reaching the adult level by approximately 2 y of age. Between 2 and 10 y of age, the GFR slightly exceeds the adult level, stabilizing at a slightly lower adult level by 10 y of age.