Urodilatin (URO) is a natriuretic peptide isolated from human urine wh
ich is thought to be produced by distal tubular cells. We measured uri
nary URO excretion in 50 healthy children and 23 children with acute (
ARF), chronic renal failure (CRF), or hereditary tubular disorders, us
ing a specific radioimmunoassay. The mean URO excreted in these four g
roups was 56, 45, 94, and 121 fmol/min per 1.73 m(2), respectively (di
fferences between first three groups not significant). The variation i
n URO excretion was larger in patients with kidney disease than in con
trols. There were significant correlations between urinary URO and sod
ium excretion in controls and CRF, but not in ARF. URO excretion also
correlated with urine flow rate in CRF. Although no correlation was fo
und between URO excretion and creatinine clearance, urinary URO was in
creased in some patients with advanced CRF, which suggests stimulated
tubular production to compensate for reduced sodium excretion. In view
of the therapeutic potential of URO in renal insufficiency, further s
tudy of the renal handling of URO is warranted.