Blood pressure is determined by the amount of blood pumped by the heart and the size and condition of the arteries. Many other factors can affect blood pressure, including the volume of water in the body: salt content of the body; condition of the kidneys; nervous system, or blood vessels; and levels of various hormones in the body.

Renovascular hypertension is a form of secondary hypertension (hypertension caused by another condition in the body). It occurs in less than 5% of all hypertensive people. Symptoms usually begin before age 30 or after age 50, depending on the cause of the damage to the kidney blood vessels.

Stenosis (narrowing) of the renal artery reduces blood flow to the kidney. Stenosis is often related to atherosclerosis but may be caused by injury to the artery that causes scarring. Other conditions such as fibromuscular dysplasia may also affect the renal arteries, resulting in stenosis. Reduced blood flow to the kidney leads to an excessive release of the hormone renin, a potent hormone that increases blood pressure.