Sex hormone diseases are often confused with unipolar major depression one study showed that men with testicular diseases were four times more likely to be diagnosed with depression. Testosterone levels decline naturally in all men after forty years of age, but few of them develop unipolar major depression. Also, testosterone has been prescribed as a treatment for depression with little success. Testosterone supplementation has improved the mood of some patients with bipolar depression, however, and also thrown some of them into mania.
If you are concerned about your testosterone level, ask your doctor about it during your next physical examination. There is a blood test for measuring testosterone levels.