Hypogonadism

Hypogonadism is insufficient production of sex hormones by the testes or ovaries, sometimes accompanied by impaired sperm or egg production. It can arise from gonadal dysfunction or inadequate hormonal signaling from the brain.

Primary hypogonadism: Hypogonadism caused by impaired function of the testes or ovaries. Gonadal failure raises pituitary signals while sex-hormone output remains low.
Testosterone replacement therapy: Treatment that supplies testosterone to people with confirmed testosterone deficiency. It can relieve deficiency symptoms but may suppress sperm production.
Klinefelter syndrome: A chromosomal condition in males, usually involving an extra X chromosome, that can impair testicular function. It is a common genetic cause of primary testicular insufficiency.
Delayed puberty: A later-than-expected onset or progression of pubertal development. It can signal hypogonadism, but constitutional delay may resolve without persistent gonadal failure.
Secondary hypogonadism: Hypogonadism caused by inadequate stimulation of the gonads by the hypothalamus or pituitary gland. Low or inappropriately normal pituitary signals point to this central form.
Hormone replacement therapy: Treatment that supplies hormones to replace those the body does not produce in sufficient amounts. Sex-hormone replacement is considered when deficiency causes symptoms or health risks.
Turner syndrome: A chromosomal condition in females involving complete or partial absence of one X chromosome. Ovarian insufficiency is a frequent consequence of this condition.
Menopause: The permanent end of menstrual periods after ovarian follicular activity ceases. It involves low ovarian hormones but is a normal life stage, unlike pathological hypogonadism.
Hypothalamic-pituitary-gonadal axis: The hormonal signaling system linking the hypothalamus, pituitary gland, and gonads. Disruption anywhere along this pathway can reduce gonadal hormone production.
Clomifene: A selective estrogen receptor modulator used to stimulate ovulation and, in some cases, endogenous testosterone production. It may raise testosterone while preserving fertility in selected men with central hypogonadism.

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