renovascular hypertension

The kidneys are exquisitely sensitive pressure sensors. When a kidney senses that its own blood supply has fallen, it assumes the whole body's pressure is too low and acts to raise it. Renovascular hypertension is what happens when a narrowed renal artery fools the kidney into that response, driving the body's blood pressure up to correct a shortage that does not really exist.

The mechanism runs through the renin–angiotensin–aldosterone system. The under-perfused kidney releases renin, triggering a hormonal cascade that constricts arteries and makes the body retain salt and water, both of which raise pressure. The two most common causes of the renal-artery narrowing are atherosclerosis, typically in older patients, and fibromuscular dysplasia, a non-atherosclerotic vessel-wall disorder seen more often in younger women.

It is one of the more common identifiable forms of secondary hypertension. Clues include hypertension that is severe, resistant to several drugs, or worsens abruptly, a sharp rise in creatinine after starting an ACE inhibitor or ARB, or a bruit over the abdomen. Treatment centers on medication and risk-factor control; opening the narrowed artery with a stent helps only selected patients and does not benefit everyone.