Urinary dopamine excretion in chronic renal disease.

We have measured unconjugated urinary dopamine and investigated its relationship to glomerular filtration rate in two groups of 22 patients with chronic renal failure matched for age and sex, one group with primary glomerular disease, the other with tubulo-interstitial disease. Urine dopamine excretion was similar in both glomerular and tubulo-interstitial disease groups, and correlated significantly with creatinine clearance. Although urinary protein excretion was significantly higher in glomerular disease, urinary sodium excretion, fractional sodium excretion, urine flow rate and free water clearance were similar in both groups and did not correlate with dopamine excretion. These results suggest that in patients with chronic renal disease, urinary dopamine excretion is mainly under the influence of the glomerular filtration rate, irrespective of the underlying pathology, and therefore interpretation of urinary dopamine excretion requires a knowledge of the patients' renal function.