Diagnostic significance of dopamine estimation using plasma and urine in patients with adrenal and renal insufficiency, renal transplantation and hypertension.

Although free and conjugated dopamine (DA) constitute most of the plasma and urine catecholamine pool, the diagnostic significance of DA estimation for the evaluation of illness is not clear. We evaluated the clinical utility of DA estimation by measuring free and conjugated DA in patients with various illness. Patients with adrenal insufficiency did not show decreases in DA concentrations but did demonstrate reductions in free and conjugated plasma adrenaline (Ad). Patients with established stage of essential hypertension exhibited decreased plasma concentrations of free and conjugated DA, although they were hyperadrenergic. In patients with chronic renal insufficiency and failure, the free DA concentration in the urine decreased depending on the severity of renal impairment. Conversely, plasma concentrations of conjugated DA are higher in patients with chronic renal failure than in normal subjects. The high plasma concentrations of conjugated DA decreased dramatically following hemodialysis and renal transplantation. Urinary free DA excretion increased markedly following renal transplantation. In conclusion, the estimation of the free and conjugated DA in plasma and urine is clinically useful for the diagnosis of adrenal insufficiency, essential hypertension, and renal insufficiency and failure. It also can be used to monitor the effectiveness of hemodialysis and renal transplantation.