INFO/WWW: The main causes or renal artery stenosis - causing renal hypertension/dysplasia - are: Arteriosclerosis/Atheroma: The stenosis of the renal artery caused by arteriosclerosis is usually located in the proximal third of the renal artery Patients with atheroma are usually older than 40. Fibromuscular hyperplasia/dysplasia: These patients are usually younger than 40 and female. Multiple narrow passages of the whole renal artery and its branches are typical for fibromuscular hyperplasia/dysplasia. Fibromuscular hyperplasia/dysplasia occurs in 60% bilateral.