Hypertension is classified by which threshold?

• A. Systolic BP >140
• B. Diastolic BP >90
• C. Systolic BP >140 OR Diastolic BP >90
• D. Both systolic and diastolic thresholds apply

Answer: (A)

Hypertension is defined by crossing a threshold in either blood pressure value. The key point is that an elevated systolic pressure or an elevated diastolic pressure alone qualifies as hypertension. Historically, the standard threshold is systolic above 140 mmHg or diastolic above 90 mmHg, so the criterion uses OR: if systolic is >140 OR diastolic is >90, the person is classified as hypertensive. Using an AND rule would miss cases where only one value is elevated, such as isolated systolic hypertension (high SBP with normal DBP) or isolated diastolic hypertension (high DBP with normal SBP). Some guidelines have updated targets, but for this question the OR criterion best reflects the traditional classification.