What is the most common cause of secondary hypertension?

Renal artery stenosis is recognized as the most common cause of secondary hypertension due to its significant impact on blood flow and kidney function. When the renal arteries are narrowed, it leads to decreased blood flow to the kidneys, which in turn triggers the renin-angiotensin-aldosterone system. This system is responsible for regulating blood pressure. The kidneys release renin in response to the perceived low blood flow, leading to increased levels of angiotensin II, causing vasoconstriction and increased blood pressure. This cascading effect can significantly elevate blood pressure levels, contributing to secondary hypertension.

While other conditions can also lead to secondary hypertension, renal artery stenosis is particularly common and clinically relevant. Coarctation of the aorta can cause hypertension, especially in the upper body, but it is less prevalent as a cause compared to renal artery stenosis. Hypothyroidism can affect blood pressure, but it typically causes lower blood pressure rather than hypertension. Cushing's syndrome is associated with elevated cortisol levels leading to hypertension as well, but it is not as frequently encountered in the general population compared to renal artery stenosis, making it the most recognized cause of secondary hypertension.