Pathophysiology of renal function and its effect on isotope studies in the workup of hydronephrosis.

Understanding renal maturation and growth is essential before adequate interpretation of radionuclide renal studies can be done. The expectation that an immature kidney draining into a dilated renal pelvis will show good washout on a diuretic renogram within 20 or 40 min is unreasonable. A physiological explanation for this is given.