What is the most common cause of secondary hypertension?

The most common cause of secondary hypertension is chronic kidney disease. This condition leads to hypertension primarily due to the kidneys' role in regulating blood pressure through the renin-angiotensin-aldosterone system. As kidney function declines, the ability to excrete sodium and fluid is impaired, leading to volume overload and subsequent elevation of blood pressure. This makes chronic kidney disease a frequent and significant contributor to secondary hypertension compared to other listed causes.

Other causes like primary aldosteronism, stress-induced hypertension, and Cushing's syndrome certainly can lead to elevated blood pressure, but they occur less frequently in the general population. Primary aldosteronism involves excessive secretion of aldosterone, leading to increased sodium retention and thus hypertension, while stress-induced hypertension tends to be more transient. Cushing's syndrome, caused by excess cortisol, can also cause hypertension but is rarer. Overall, chronic kidney disease is the most prevalent underlying condition responsible for secondary hypertension in patients.