What is the primary cause of orthostatic hypotension?

The primary cause of orthostatic hypotension is a rapid change of position, which can lead to a sudden drop in blood pressure when a person stands up after sitting or lying down. This condition occurs when the body fails to regulate blood pressure appropriately in response to these changes. When a person stands, gravity causes blood to pool in the legs, reducing the amount of blood returning to the heart, which can result in decreased cardiac output and lower blood pressure.

Dehydration can also contribute significantly to orthostatic hypotension. When the body is dehydrated, there is less blood volume available, which can exacerbate the effects of standing up suddenly by further diminishing the blood flow and leading to a drop in blood pressure.

Certain medications can additionally cause orthostatic hypotension as a side effect by altering blood pressure or affecting the autonomic nervous system, which helps control blood flow and blood pressure.

Since all these factors—rapid changes in position, dehydration, and medication effects—are recognized contributors to the development of orthostatic hypotension, they collectively point to the conclusion that the most comprehensive answer reflects this multifactorial nature. Therefore, the correct choice encapsulates these various causes, highlighting that the condition can arise from a combination of diverse situations