ABSTRACT
Hypogonadism refers to a deficiency in androgen secretion and/or sperm production. Most androgendeficient patients are infertile, while most infertile patients have serum testosterone levels within the normal range. Defects of steroid secretion by the Leydig cell may be either primary or secondary. The clinician must be able to distinguish one condition from the other in order to plan appropriate treatment, and the basic scientist focusing on andrology should understand the clinical implications of dysregulation of the reproductive axis.
