American Board of Internal Medicine (ABIM) Certification Practice Exam

What defines orthostatic hypotension based on systolic pressure?

1. At least a 10 mmHg fall

2. At least a 20 mmHg fall

3. No change in pressure

4. At least a 30 mmHg fall

The correct answer is: At least a 20 mmHg fall

Orthostatic hypotension is characterized by a significant drop in blood pressure upon standing, reflecting a failure of the cardiovascular system to adequately respond to changes in posture. The standard definition for orthostatic hypotension specifies that there must be at least a 20 mmHg decrease in systolic blood pressure when a person transitions from a supine position to standing. This drop indicates a deficiency in the body's autonomic regulation, leading to symptoms such as dizziness or lightheadedness. A fall of at least 20 mmHg is clinically significant because it is largely indicative of the potential for impaired cerebral perfusion, which can manifest as symptoms during postural changes. This definition is widely used in both clinical practice and research, making it essential for correctly identifying patients who may require further evaluation or management due to potential underlying conditions. While less than 20 mmHg drops may occur, they typically do not signify orthostatic hypotension. The other thresholds for pressure changes mentioned, such as 10 mmHg and 30 mmHg, do not align with the established criteria for diagnosing orthostatic hypotension, which is why they are not considered correct. Therefore, the appropriate threshold for defining this condition is indeed a fall of at least 20 mmHg in