AGE-RELATED-CHANGES OF URINARY DOPAMINE EXCRETION IN HYPERTENSIVE PATIENTS

Background: Increasing evidence suggests that the kidney is the main source of urinary dopamine and that this intrarenally formed dopamine plays a role in sodium and water homeostasis. Because older subjects are known to handle a sodium load less efficiently than younger subjects, and because the prevalence of hypertension increases with age, we found it of interest to study the effect of age on the renal production of dopamine. Methods: We retrospectively determined urinary catecholamine excretion (24-hour urine collections) of 1000 hypertensive patients and correlated the amount of catecholamines excreted with age. Results: A significant negative correlation between age and dopamine excretion (r = - 0.38, P < 0.001) and between age and creatinine excretion (r = 0.37, P < 0.001) was observed. The percentage decrease of urinary dopamine with age (0.65% per year) was comparable to the percentage decrease of urinary creatinine with age (0.55% per year). Conclusions: Urinary dopamine production decreases with age, possibly as a part of the global loss of renal function.