Please list the specific tests for finding the causes of low testosterone. Why don't doctors look first for the cause before administering thw cure?

Low testosterone. Also known as hypogonadism, this condition is diagnosed by blood tests to check hormone levels, and should be done first thing in the morning. In my own practice, I do not and would not administer testosterone replacement therapy without first confirming the diagnosis with lab tests. You may wish to obtain a second opinion if you uncertain about your management.