- Severe hypertension documented by (1) Sitting systolic blood pressure or sitting diastolic blood pressure more than 20 mmHg above the 95th percentile for age, gender, and height without antihypertensive therapy, (2) Sitting systolic blood pressure or sitting diastolic blood pressure more than 12 mmHg above the 95th percentile for age, gender, and height while receiving active therapy, or (3) hypertensive encephalopathy within the previous 5 months.