Twenty-four-hour ambulatory blood pressure(ABP) monitoring has become increasingly popular for diagnosing and treating hypertension. Therefore the reference value of normotensive subjects was necessary for interpretation of hypertensive subjects. Several studies were reported on reference values in normotensive subjects. The purpose of this study was to determine 24-hour ABP in normotensive Korean adults stratified for sex and five age groups. This study also assessed ABP in relation to a family history of hypertension, smoking and body mass index(BMI).

ABP monitoring was performed in 200 healthy normotensive volunteers(ranged in age from 20 to 69 years, five decades, 20 men and 20 women per each decade), over 24 hours, taking measurement at 30-min intervals. The 24-hour interval was divided into day-time(6am-10pm) and night-time(100pm-6am) periods. Mean ABP and pressure loads(percentage of systolic readings>140mmHg, diastolic readings>90mmHg) were obtained.

The mean ABP in 200 subjects was 113±8.6/72±6.9mmHg over 24 hours, 117±9.7/75±7.0mmHg during day-time, and 106±9.8/67±8.3mmHg at night-time, and pressure loadd averaged 5.1±7.4/7.9±8.9% over 24 hours. The +2 standard deviation(SD) as the upper limit of normal was 130/86mmHg over 24 hours in 200 subjects. The mean ABP and pressure load were 116±7.6/74±7.6mmHg and 6.4±8.3/10.1±10.2% in 100 subjects of men, and 110±8.3±70±6.6mmHg, 3.7±6.0/5.7±6.8% in women. Mean ABP and pressure load showed significant difference in relation to age group and sex, however, no significant difference in relation to a family history of hypertension or smoking. In relation to BMI group, diastolic blood pressure and diastolic pressure load were significantly different.