Investigations for secondary amenorrhea when indicated for patients younger than 45 years
| Differential diagnosis | Diagnostic test |
|---|---|
| Premature ovarian insufficiency or early menopause | FSH, estradiol |
| Hyperprolactinemia | Serum prolactin |
| Pregnancy | β-hCG |
| Hypo- or hyperthyroidism | TSH |
| Polycystic ovary syndrome | Clinical diagnosis (i.e., Rotterdam criteria), with or without total serum testosterone |
Note: FSH = follicle-stimulating hormone, hCG = human chorionic gonadotropin, TSH = thyroid-stimulating hormone.