Predictors of plasma and urinary catecholamine levels in normotensive and hypertensive men and women

Age, sex, hypertension and dietary sodium are proposed to affect plasma and urinary catecholamines. Yet no prior study has examined the simultaneous effects of these factors within the same study population. So results may have been confounded by factors not determined. We investigate, for the first time, the impact of simultaneously determined predictors of plasma and urinary catecholamines and the relationship of catecholamines with the diagnosis of hypertension. Hypertensive and normotensive subjects (n=308) were studied off antihypertensives in liberal and low sodium balance. 24 h urinary catecholamines (norepinephrine and epinephrine) were measured. Plasma catecholamines were measured supine after overnight fast. Repeated measures multivariate linear regression models examined the effect of sex, race, age, body mass index (BMI), dietary salt (liberal salt vs low salt), hypertension status and mean arterial pressure (MAP) on plasma and urinary catecholamines. Logistic regression determined the relationship of catecholamines with diagnosis of hypertension. Dietary sodium restriction and increasing age predicted increased plasma and urinary norepinephrine, with sodium restriction having the greatest effect. Female sex predicted lower urinary and plasma epinephrine. Neither plasma nor urinary catecholamines predicted the diagnosis of hypertension. In summary, specific demographic factors variably impact catecholamines and should be considered when assessing catecholamines in research and clinical settings.