Renal artery stenosis is a condition where the arteries supplying blood to the kidneys become narrowed. This narrowing can reduce blood flow, leading to high blood pressure and potential kidney damage. It is often caused by a buildup of plaque, a condition known as atherosclerosis, or by fibromuscular dysplasia, particularly in younger women. Symptoms may include high blood pressure that is difficult to control and, in some cases, kidney dysfunction. Diagnosis typically involves imaging tests like ultrasound or CT angiography. Treatment options may include medications, lifestyle changes, or procedures to restore normal blood flow.