Topic overview

Start with the big picture

Amenorrhea is classified by menstrual history: primary amenorrhea concerns absent menarche by specified age criteria, while secondary amenorrhea describes missed cycles or months in someone who previously menstruated. Evaluation begins by ruling out pregnancy, then considers causes involving the hypothalamus, pituitary, ovaries, uterus, or outflow tract. Medication effects are also relevant, including those associated with some contraceptives, dopamine antagonists, GnRH agonists, chemotherapy, and opioids. Initial testing may include hCG, FSH, LH, prolactin, and TSH, with estradiol considered as needed. Patterns in these results can guide investigation of conditions such as hyperprolactinemia, ovarian insufficiency, hypothalamic amenorrhea, or anovulation. This overview introduces the diagnostic framework; individual findings and clinical context are needed to determine appropriate next steps.