Externally Peer Reviewed Important changes have occurred in the measurement, epidemiology, and significance of childhood blood pressure since the publication of the first edition of the Clinician's Handbook. Elevated blood pressure in some children may represent the early onset of essential hypertension. Blood pressure varies throughout the day in children and adults because of normal diurnal fluctuation and other factors such as physical activity and emotional stress.
Body size is the most important determinant of blood pressure in children.
Hypertension is defined as average systolic or diastolic blood pressure greater than or equal to the 95th percentile for age, sex, and height measured on at least three separate occasions. Elevated blood pressure must be confirmed on repeated visits before characterizing an individual as having hypertension. A more precise characterization of an individual's blood pressure level is an average of multiple measurements taken over weeks to months. Beginning age and periodicity are not specified. This recommendation is based on the proven benefits of early detection of treatable causes of secondary hypertension.