Which description best defines orthostatic hypotension?

• A. A rapid rise in blood pressure with activity.
• B. A sustained increase in blood pressure when standing.
• C. Dizziness when standing after long sitting.
• D. A sudden drop in blood pressure when rising from lying to sitting or standing.

Answer: (D)

Orthostatic hypotension occurs when blood pressure falls too much after you move into an upright position. When you stand, gravity pulls blood toward the legs, and your body normally compensates by increasing heart rate and narrowing (constricting) blood vessels to keep blood flowing to the brain. If that adjustment is insufficient, brain perfusion drops, causing a drop in blood pressure and potentially dizziness or faintness.

The defining feature is a measurable drop in blood pressure after standing from lying down—typically a drop of about 20 mmHg in systolic pressure or 10 mmHg in diastolic pressure within a few minutes. The described scenario matches this: a sudden drop in blood pressure when rising from lying to sitting or standing, which is the key sign of orthostatic hypotension. Dizziness can accompany it, but the crucial element is the actual blood pressure decrease with position change.

The other descriptions don’t capture the essence: an increase in blood pressure with activity is the opposite of orthostatic hypotension; a sustained increase when standing describes standing hypertension rather than a postural drop; dizziness after long sitting may occur for other reasons and doesn’t specify the critical blood pressure change that defines orthostatic hypotension.