Which of the following defines orthostatic hypotension?

• A. A drop in systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg within 3 minutes of standing, test by measuring after moving from seated or lying to standing.
• B. A rise in diastolic BP ≥15 mmHg within 2 minutes of standing.
• C. A drop in heart rate after standing.
• D. A drop in mean arterial pressure by 5 mmHg within 5 minutes of standing.

Answer: (A)

Orthostatic hypotension is defined by a fall in blood pressure when you stand up, due to blood pooling in the legs and an inadequate compensatory response to maintain cerebral perfusion. The standard definition uses specific threshold changes: a drop in systolic blood pressure of 20 mmHg or a drop in diastolic blood pressure of 10 mmHg within 3 minutes of standing, with the measurement taken after moving from a seated or lying position to standing. In practice, clinicians measure BP while supine, then repeat after standing (often at 1 and 3 minutes) to see if these thresholds are met, and they’ll note any accompanying symptoms like dizziness or lightheadedness.

This is the best option because it captures both the direction (a drop in pressure) and the exact magnitude and timing that define orthostatic hypotension. The alternative described—a rise in diastolic BP, or a drop in heart rate, or a smaller, later change in mean arterial pressure—does not reflect the characteristic postural decrease in BP that defines this condition.