Table 1.
| Physiologic |
| Neonatal |
| Pubertal |
| Involutional |
| Pathologic |
| Neoplasms |
| Testicular |
| Pituitary |
| Breast tumors |
| Adrenal |
| Liver |
| Human Chorionic Gonadotropin—ectopic production |
| Lymphoma/leukemia |
| Endocrinopathies |
| Hypogonadism |
| Syndromes: Klinefelter, Kallman's |
| Androgen insensitivity |
| Hermaphroditism |
| Enzymatic defects of testosterone synthesis |
| Testicular injury/regression |
| Hyperthyroidism |
| High aromatase |
| Adrenal hyperplasia |
| Corticotropin deficiency |
| Chronic Illnesses: |
| Liver disease |
| Renal disease |
| Malnutrition |
| Cystic fibrosis |
| AIDS |
| Ulcerative Colitis |
| Medications (see Table 3) |