Blockage of the arteries to the kidneys can be a cause of high blood pressure in a small number of patients with hypertension. The narrowed arteries lead to decreased blood flow to the kidney.  The kidney responds by sending out a hormone messenger called Renin which elevates blood pressure in the entire body, thus creating more blood flow to the kidney, but in the process producing damaging high blood pressure for the entire body.  In young people this may be caused by a condition called fibromuscular dysplasia.  In older people who are at risk for arteriosclerosis (smokers, people with diabetes, elevated cholesterol) the narrowing is caused by plaque buildup in the kidney artery wall.

The current state of the art is to image the arteries with Magnetic Resonance Angiography or MRA.  If a narrowed artery is found, treatment with balloon angioplasty is usually possible.