What is the primary cause of secondary hypertension?

The primary cause of secondary hypertension is renal artery stenosis. This condition results from the narrowing of the arteries that supply blood to the kidneys, leading to reduced blood flow. In response to this, the kidneys release hormones such as renin, which in turn activates the renin-angiotensin-aldosterone system (RAAS). This system increases blood pressure by causing blood vessels to constrict and promoting sodium and water retention, ultimately leading to hypertension.

Renal artery stenosis is a significant cause of secondary hypertension, especially in patients who are younger or have sudden-onset hypertension. The functional relationship between the kidneys and blood pressure regulation makes this condition a key player in secondary hypertension scenarios.

While adrenal gland tumors, obstructive sleep apnea, and thyroid disorders can also contribute to secondary hypertension, they are not as universally recognized as leading causes in clinical practice. Adrenal tumors can cause hormone imbalances, obstructive sleep apnea contributes to intermittent hypoxia and sympathetic nervous system activation, and thyroid disorders can influence blood pressure through metabolic changes. However, renal artery stenosis is often highlighted as a critical and prevalent cause in medical literature and clinical guidelines.