Secondary Amenorrhea
Secondary amenorrhea is the absence of menses for ≥ 3 cycles (or 6 months) in a woman who previously had regular menses.
Evaluation Steps (The “First Four” Tests)
- Pregnancy Test (β-hCG): Must always be performed first to rule out pregnancy.
- TSH: To rule out thyroid dysfunction (hypo- or hyperthyroidism).
- Prolactin: To screen for hyperprolactinemia (pituitary adenoma, medications).
- FSH: To distinguish between ovarian failure (high FSH) and hypothalamic/pituitary causes (low/normal FSH).
Common Etiologies
| Category | Examples |
|---|---|
| Hypothalamic | Functional hypothalamic amenorrhea (excessive exercise, low BMI, stress). |
| Ovarian | PCOS, Premature Ovarian Insufficiency (POI). |
| Uterine | Asherman syndrome (intrauterine adhesions post-curettage). |
High-Yield Exam Pearl:
- Progestin Challenge Test: Used to assess estrogen status and outflow tract patency. Bleeding after progestin indicates that the patient has anovulatory cycles (e.g., PCOS) with adequate estrogen.
- Asherman Syndrome: Suspect in patients with a history of uterine instrumentation (D&C) who fail to bleed after a combined estrogen-progestin challenge.