Hypogonadism
Hypogonadism is the state of inadequate production of sex hormones by the gonads. Among other causes of primary hypogonadism, Klinefelter syndrome is the leading cause of gynecomastia. It is a disorder of abnormal chromosomal pairing, which results in testicular insufficiency. One of the key manifestation is gynecomastia.
Hypogonadism may be acquired due to testicular injury, castration or tumors of the gonads. Hypogonadism may also be a result of inadequate stimulation of the gonads by the pituitary or hypothalamus hormones.