| Cryptorchidism, testicular torsion, and trauma6 |
| Postpubertal mumps orchitis7 |
| Congenital adrenal hyperplasia |
| Obesity8 |
| Diabetes and poor glycemic control9 |
| Erectile dysfunction10,11 |
| Multiple sclerosis and spinal cord injury12 |
| Hyper or hypothyroidism13 |
| Varicocele14 |
| Prostatitis, epididymitis, sexually transmitted diseases15 |
| Malignancies (Hodgkin16 and testicular cancer17) and any endocrine or metabolic effects of cancer18 |