Urinary catecholamine excretion in relation to renal function

The urinary excretions of the free catecholamines noradrenaline, adrenaline and dopamine were measured in 50 patients (33 men and 17 women) with chron ic renal failure. Stability studies showed that the catecholamines were sta ble in unacidified urine as long as the pH was not greater than 7.5 and the urine was acidified within 2-3 h of collection. The outputs of noradrenali ne and dopamine correlated positively with creatinine clearance and in pati ents with clearances above 10 mL/min were similar to those in healthy Volun teers (n = 20). However, adrenaline output was not correlated with creatini ne clearance although it was lower in patients with renal failure compared with healthy volunteers. The urinary free catecholamine output during the f irst 10 days after a renal transplant was significantly less than normal, p resumably because renal function was still impaired. However, in patients t reated with cyclosporin A (CyA) combined with prednisolone the catecholamin e excretion was lower compared with those treated with CyA and azathioprine . Impairment in renal function can have a marked effect on the output of fr ee catecholamines and must be borne in mind when interpreting Values that m ay have pathological significance.