Version July 2025
| Congenital abnormalities |
| Klinefelter syndrome |
| Other chromosomal abnormalities |
| Mutation in the FSH and LH receptor genes |
| Cryptorchidism |
| Disorders of androgen synthesis |
| Myotonic dystrophy |
| Acquired diseases |
| Infections, especially mumps |
| Radiation |
| Alkylating agents |
| Suramin |
| Ketoconazole |
| Environmental toxins |
| Trauma |
| Testicular torsion |
| Autoimmune damage |
Chronic systemic illnesses
|
| Idiopathic |
