Hello my friend I am Dr. Arianisa Thanks for your question on HCM There are several causes which tend to be grouped into those that are mainly physical and those that are mainly due to mental health (psychological): 1.Reduced blood flow to the penis. This is, by far, the most common cause of ED in men over the age of 40. 2.Diabetes. This is one of the most common causes of ED. Diabetes can affect blood vessels and nerves. 3.Hormonal causes. For example, a lack of a hormone called testosterone which is made in the testes. 4.Alcohol and drug abuse. 5.Injury to the nerves going to the penis. For example, spinal injury, following surgery to nearby structures, fractured pelvis, radiotherapy to the genital area. Depending on your symptoms, likely cause of the ED, age, etc, your doctor may suggest that you have some tests: A blood test to check the level of cholesterol and other fats (lipids).Blood sugar level.Blood tests to rule out kidney and liver disease.A urine test.A check of your blood pressure. A heart tracing (ECG).Other heart tests which are sometimes done, where appropriate, if heart disease is suspected. A referral to a specialist is sometimes needed for assessment and treatment. However, GPs are now treating more cases of ED than previously, as the treatment options have improved in recent years. Your GP is more likely to suggest referral if you have been found to have an hormonal problem, if the cause is related to another condition like circulatory problems. Hope this information is helpful to you Best regards