| Primary hypogonadism – High FSH and LH |
| Congenital |
| Chromosomal abnormalities (Turner syndrome – 45,XO; Klinefelter syndrome – 47,XXY) |
| Anorchia (vanishing testis) |
| Acquired |
| Autoimmune or postinfectious |
| Following trauma or surgery |
| Chemotherapy, radiation therapy |
| Secondary hypogonadism – Low to normal FSH and LH |
| Acquired |
| Tumors |
| Benign tumors and cysts |
| Craniopharyngiomas |
| Germinomas, meningiomas, gliomas, astrocytomas |
| "Functional" gonadotropin deficiency |
| Constitutional delay of growth and puberty |
| Chronic systemic disease |
| Acute illness |
| Malnutrition |
| Hypothyroidism, hyperprolactinemia, diabetes mellitus, Cushing's disease |
| Anorexia nervosa, bulimia |
| Infiltrative diseases |
| Hemochromatosis |
| Granulomatous diseases |
| Histiocytosis |
| Head trauma |
| Pituitary apoplexy |
| Drugs – Marijuana |
| Congenital |
| Isolated GnRH deficiency (also known as idiopathic hypogonadotropic hypogonadism) |
| Without anosmia |
| With anosmia (Kallmann syndrome) |
| Associated with adrenal hypoplasia congenita |
| GnRH deficiency associated with intellectual disability/obesity |
| Laurence-Moon-Biedl syndrome |
| Prader-Willi syndrome |
| Idiopathic forms of multiple anterior pituitary hormone deficiencies |
| Congenital brain malformations causing GnRH or gonadotropin deficiencies (often associated with craniofacial anomalies) |
