January 1, 1983
View Full PaperAge-dependence of hypertensive-normotensive differences in plasma norepinephrine.
Key Result
Young patients (<40 years) with essential hypertension had significantly higher plasma norepinephrine concentrations than normotensive controls (317 vs 245 pg/ml, p<0.01).
Study Design
Type
Observational (n=320)
Structured PICO
Are venous plasma norepinephrine concentrations elevated in patients with essential hypertension compared to normotensive controls?
P
Population
320 resting, supine individuals, comprising 191 patients with essential hypertension and 129 normotensive controls.
C
Comparator
Normotensive controls
O
Outcome
Venous plasma norepinephrine (NE) concentrationssurrogate
Increased sympathetic nervous system activity, as indicated by elevated plasma norepinephrine, appears to be a feature primarily of the early stages (younger age) of essential hypertension.
Main Result
Absolute Event Rate: 317% vs 245%
p-value: p=<0.01
Abstract
We compared venous plasma norepinephrine (NE) concentrations in 191 resting, supine patients with essential hypertension and 129 normotensive controls. Among normotensives, plasma NE increased significantly with age, but among hypertensives, no age-related increase occurred, due to relatively high NE values among young hypertensives. When patients and controls less than 40 years old were considered, hypertensives showed significantly higher plasma NE than the controls (317 vs 245 pg/ml, t = 3.15, p less than 0.01); but above the age of 40 years, no significant hypertensive-normotensive difference was obtained. These results, predicted by recent literature reviews, help to resolve the persistent controversy about sympathetic neural activity in essential hypertension, since such activity appears to be abnormal mainly in young patients. The data are consistent with increased sympathetic nervous system activity in the early stages of essential hypertension.