Ambulatory blood pressure in young subjects with familial history of hypertension.

Office blood pressure (BP), ambulatory blood pressure, (one determination every 15 min, over an entire 24 h span), were measured in 206 young male subjects, including 96 individuals having first degree familial history of hypertension (the F group) and 110 control subjects, matched for age, having no familial history of hypertension (the C group). In both groups, age ranged from 19 to 25 y. After a complete clinical and laboratory examination, all subjects were diagnosed as in good health. In particular, none had cardiac, renal or neurologic involvement. No subject received medication. Over the whole sample, 126 subjects had normal office BP and 80 had borderline office BP. No difference was found in office diastolic BP between the C and F groups. Office systolic BP was somewhat higher in the F group, when compared to the C group, but the difference was in the limit of statistical significance (0.05 less than p less than 0.10). In contrast, ambulatory systolic BP was significantly higher in the F group, when compared to the C group, the difference (0.05 less than p less than 0.001) occurred in daytime and at night. The above difference was more significant (p less than 0.02 to p less than 0.005) and persisted over larger time-spans when only subjects with normal office BP in the C and F groups are compared. In contrast, when restricted to the borderlines only, office and ambulatory BP was the same in subjects with and without familial history of hypertension.