[Diagnosis of urine transport disorders. Diuresis renography]

Abstract

Congenital urinary tract malformations are frequently the cause of urinary transport disturbances. However, not all the malformations or obstructions presenting sonographically as hydronephrosis have to be treated surgically. The Whitaker test, an invasive diagnostic procedure to establish the urodynamic relevance of an obstruction, does not provide a reliable estimate of prognosis; spontaneous cures in cases of obstruction have been reported. Diuresis renography offers several advantages as compared with the Whitaker test, for example a more physiological basis, less observer dependency, better reproducibility and--last but not least--non-invasiveness. However, diuresis renography has to be carried out according to a strictly standardized protocol. Sufficient hydration (20 mg/kg body weight) and bladder catheterization (to rule our reflectory transport disturbances) are mandatory. Today, 123I-OIH or 99mTc-MAG3 are the radiopharmaceuticals of choice; the activity for children has to be reduced in relation to body surface. To stimulate diuresis, furosemide (0.5-1 mg/kg of body weight) has to be given. For the evaluation of diuresis renography, sequential scintigrams as well as functional curves have to be used. It is strongly recommended that diuresis renography be combined with clearance determinations separately for the two kidneys. The interpretation of diuresis renography should not rely only on quantitative curve parameters but--above all--on visual analysis of the functional curves. However, in cases of proven obstruction, diuresis renography--like the Whitaker test--cannot accurately predict the prognosis in any individual case. If renal function is normal and there is no difference between the left and the right kidney, a wait-and-see attitude seems to be justified.(ABSTRACT TRUNCATED AT 250 WORDS)