To complete the evaluation of the causes of male infertility, hormonal analysis is imperative in cases of poor semen analysis results or azoospermia. In some cases, these conditions result from insufficient stimulation by the hormones secreted by the pituitary gland, follicle stimulating hormone (FSH) and luteinizing hormone (LH). In other cases, inadequate production of other hormones, such as thyroid stimulating hormone, prolactin, or insulin, can have a negative effect on sperm development. These tests must be performed to distinguish between primary testicular failure and secondary failure due to factors from other sources than the testis. This distinction is important for the choice of an appropriate treatment plan.