Evaluation of (123)I-orthoiodohippurate single kidney clearance rate by renal sequential scintigraphy in a large cohort of likely normal subjects aged between 0 and 18 years.

Purpose: Age-related values of (123)I-orthoiodohippurate (OIH) single kidney clearance rate (Cl) were estimated in a large cohort of likely normal children aged between 0 and 18 years.

Methods: Among 4,111 children examined in the past 10 years, 917 were selected with the following inclusion criteria: (a) mild ultrasonographic hydronephrosis with right differential renal function (DRF) <53% and >47% (498 pts), (b) known or suspected urinary tract infection with normal ultrasound, serum creatinine and DMSA and DRF <53% and >47% (419 pts). (123)I-OIH-Cl was assessed using a validated gamma camera method. Children were divided into 21 age classes: from 0 to 2 years, eight 3-month classes; from 2 to 14 years, twelve 1-year classes; from 14 to 18 years, one 4-year class.

Results: Cl, plotted against age, was fitted using an increasing function (y=a-be-cx). Mean (123)I-OIH-Cl of 1,834 kidneys was 306+/-22 ml/min/1.73 m(2) BSA. Mean (123)I-OIH-Cl of the right and left kidneys was 307+/-23 and 305+/-22 ml/min/1.73 m(2) BSA, respectively (p<0.002). The best-fitting (123)I-OIH-Cl growing function was: Cl=311-230e-0.69xAge (months). (123)I-OIH-Cl improved progressively starting from birth, reaching 96% and 98% of the mature value at 1 and 1.5 years, respectively. (123)I-OIH-Cl at birth (age=0) was 81 ml/min/1.73 m(2) BSA. After 18.6 days of life, the renal function had doubled its starting value, and it reached a plateau of 311 ml/min/1.73 m(2) BSA at 2 years.

Conclusion: This work represents a systematic evaluation of ERPF by a gamma camera method in a large cohort of selected likely normal paediatric subjects.