Variation of normal (constitutional delay) In females, prolonged high level of physical exertion, e.g. from being an athlete Systemic disease, e.g. Inflammatory bowel disease, chronic renal failure Undernutrition e.g. anorexia nervosa, zinc deficiency Hypothalamic defects and diseases e.g. Prader-Willi syndrome, Kallmann syndrome Pituitary defects and diseases e.g. hypopituitarism Gonadal defects and diseases e.g. Turner syndrome, Klinefelter syndrome, Testicular failure due to mumps orchitis, Coxsackievirus B, irradiation, chemotherapy, or trauma. Testicular failure is treated with testosterone replacement,[2] Ovarian failure.[2] Absence or unresponsiveness of target organs e.g. androgen insensitivity syndrome, Müllerian agenesis Other hormone deficiencies and imbalances, Endocrine disorders.[3] e.g. hypothyroidism, Cushing's syndrome Cystic fibrosis[4] Mutations in FSHB[5] Frasier syndrome[6] Various forms of congenital adrenal hyperplasia.[3] Gonadotropin deficiency, resulting from a number of congenital and acquired abnormalities of the central nervous system Biedl-Bardet syndrome Brain tumors e.g. craniopharyngioma, prolactinoma, germinoma, glioma; diseases of hypothalamus, irradiation and trauma.