Ambulatory blood pressure measurements in children and young adults selected by high and low casual blood pressure levels and parental history of hypertension: the Bogalusa Heart Study.

Ambulatory blood pressure measurements were obtained in 57 children and young adults selected by prior high or low casual blood pressure levels and parental history of hypertension. Considerable variation in blood pressure levels occurred over 24 hours, with generally higher levels occurring in those so selected. Parental history had a small influence on higher levels, although statistical significance was not shown. Persons with higher blood pressure levels did not reach levels as low during sleep, especially with regard to the systolic measurement, and a greater variability was noted in those selected for higher levels. Although differentiation of persons with high and low blood pressure levels can be obtained by noting average levels persisting above a cut point, for example, 140/85, in growing children an arbitrary 90th percentile based on age, height, and weight may be more appropriate. Ambulatory monitoring showed that young persons, selected by casual measurements as having high blood pressure, have a greater percentage of high levels persisting over a 24-hour period, comprising a greater blood pressure load. These observations also showed that even two series of casual measurements may misclassify a person as having hypertension. Ambulatory blood pressure monitoring will enhance understanding of the early natural history of hypertension and allow improved prevention of the disease.