[Imaging and functional parameters in diagnosis of obstructive nephropathy].

Obstruction of the kidney leads to terminal kidney failure within a few years. Therefore, early recognition of such obstruction is of importance. Non-invasive diagnostic ultrasound examination now allows intrauterine visualization of a suspected obstruction. However, the implications of such a dilated ureteral pelvic system are obscure. Whether there is obstruction or dilatation can only be evaluated postnatally by a nuclear technique. The aim of our study was to measure the recovery of kidney function. We investigated 13 kidneys of 9 newborns or small infants (up to 2 years). The follow-up was continuous for up to 29 days. The parameters were: urine output (24-h clearance), glomerular filtration rate, fractional excretion of sodium and potassium, free water clearance, total protein excretion, albumin and alpha 1 microglobulin excretion. The urine output fell from 0.3 to 0.12 ml/min within 14 days after relief of obstruction. The glomerular filtration rate rose from nearly 30 ml/min to about 50 ml/min within a week. The fractional excretion of sodium and potassium indicated recovery of the proximal tubli. The fractional sodium excretion fell below 1% within 4 days. The free water clearance reflects the concentrating ability of the kidney, and in kidneys from newborns it had only positive values, while in kidneys of children older than 6 months there were also negative values. The protein excretion and the albuminuria showed recovery of the glomerular as well as the tubular system.(ABSTRACT TRUNCATED AT 250 WORDS)