The main causes of too thin blood vessels are congenital. Congenital abnormalities in blood vessel development may lead to thin blood vessels, which usually do not cause great harm to the body. If the blood vessels are thin and affect the blood supply, it may lead to ischemia of the limbs. There is also intimal hyperplasia caused by atherosclerosis, which can occupy the lumen and cause the blood vessels to become thin, usually pathologically, and the patient has no symptoms in mild cases. If the blood vessels are too thin and affect the blood supply to the distal tissues, it will lead to distal ischemia. Different organs will have different clinical manifestations of ischemia and need to be examined and treated.