Urinary excretion of norepinephrine, epinephrine and dopamine was investigated in children with diabetic ketoacidosis. Besides pronounced hyperglycemia and metabolic acidosis, severe hypovolemia was also observed. At the onset of the study, urinary excretion of norepinephrine, epinephrine and dopamine was markedly elevated. Fluid replacement decreased urinary catecholamine excretion. Norepinephrine: 996 +/- 97 vs. 253 +/- 29; dopamine: 5,108 +/- 480 vs. 3,175 +/- 715; epinephrine: 402 +/- 81 vs. 77 +/- 200 pmol/min/1.73 m2. During ketoacidosis, there was a significant negative correlation between urinary norepinephrine excretion and endogenous creatinine clearance. Urinary output of both norepinephrine and dopamine correlated significantly with diuresis, while sodium excretion only correlated with dopamine excretion. Our data suggest that in diabetic ketoacidosis increased urinary excretion of norepinephrine may participate in renal hypoperfusion and hypofiltration. Elevated renal dopamine production contributes to sodium loss, characteristic for diabetic ketoacidosis.