What are probable causes of hypogonadism?

Depends. . There is primary and secondary hypogonadism. In men, primary hypogonadism is caused by testicular cancer, trauma, or genetic disorders. Secondary hypogonadism is commonly caused by depression, anxiety, obesity, head trauma, aging, or other chronic diseases.
Different causes. May be a problem with the gland that regulates the ovaries or/and testicles: the pituitary gland, or a problem with the ovaries/ testicles. Radiation, chemotherapy, surgeries, some medications, immune conditions, infections, tumors or inflammatory diseases all can potentially cause hypogonadism. If worried, speak with your doctor or seek referral to endocrinologist.