Orthostatic hypotension is characterized by a drop in blood pressure when standing. Which option best represents this concept?

• A. BP rise when standing
• B. Pulse increase without BP change
• C. BP is unchanged by position
• D. BP drop when standing

Answer: (D)

Orthostatic hypotension happens when standing causes a fall in arterial pressure because the shift of blood into the legs reduces venous return and the body's reflexes fail to compensate. When you stand, gravity pulls blood toward the lower body, which decreases how much returns to the heart. In healthy people, the heart rate rises and peripheral vessels constrict to keep blood pressure stable. If that response is blunted or there isn't enough blood volume, the systolic pressure (and often diastolic) falls, sometimes quickly, leading to dizziness or fainting. Clinically, a drop of 20 mm Hg systolic or 10 mm Hg diastolic within 3 minutes of standing defines orthostatic hypotension. The option describing a drop in blood pressure upon standing best represents this condition. The other patterns do not fit: a rise in blood pressure with standing would be a different phenomenon; an increased pulse without a BP change isn't the orthostatic drop; and unchanged blood pressure with position indicates no orthostatic effect.