[Pharmacokinetic aspects of excretory urography in children]

Contrast media able to pass through the kidney were a major advance in the field of radiodiagnostics. Excretory urography is usually performed using metabolically-inactive substances which accumulate in the kidney and kidney-pelvis. A two-compartment model has always been used so far for pharmacokinetic evaluation of this. However, in doing so, the kidney pelvis was not taken in account. A further compartment was therefore added to this model which enables all the physiological processes demonstrated by excretory urography to be included in the evaluation. With this model, blood and urine levels can be used at the same time to calculate pharmacokinetic variables, as shown in 6 pediatric patients. In addition to the cumulative excretion of urine and blood levels of the contrast medium, the concentrations of the latter in the renal pelvis are shown. Particular attention is paid to the effects of two important factors in investigations using contrast medium--diuresis and total body fluid volume.