Amenorrhea

The clinician evaluates amenorrhea systematically, distinguishing primary amenorrhea (no menarche by age 15 with normal secondary sexual characteristics, or no menarche by age 13 without secondary sexual development) from secondary amenorrhea (absence of menses for 3 or more months in women with previously regular cycles, or 6 or more months with previously irregular cycles). The first step in evaluating any amenorrhea is a pregnancy test. For secondary amenorrhea, the clinician applies a stepwise algorithm: (1) exclude pregnancy (serum beta-hCG), (2) assess TSH and prolactin (hypothyroidism and hyperprolactinemia are common reversible causes), (3) progesterone challenge test (medroxyprogesterone 10 mg for 10 days -- withdrawal bleeding indicates adequate estrogen and rules out outflow tract obstruction; no withdrawal bleeding suggests estrogen deficiency or anatomic abnormality), (4) estrogen-progesterone challenge (combined OCP for 1 cycle -- bleeding confirms functional endometrium; no bleeding suggests Asherman syndrome or outflow obstruction), (5) FSH and LH levels (elevated FSH indicates ovarian failure/primary ovarian insufficiency; low/normal FSH suggests hypothalamic or pituitary cause -- functional hypothalamic amenorrhea from stress, excessive exercise, low body weight, or pituitary pathology requiring MRI). The clinician manages the underlying cause: hypothalamic amenorrhea responds to addressing underlying factors (weight restoration, stress reduction, decreased exercise intensity); PCOS management includes lifestyle modification, combined OCP for cycle regulation and androgen suppression, and metformin; premature ovarian insufficiency requires hormone replacement therapy for bone and cardiovascular protection until the average age of natural menopause. The clinician assesses bone density in prolonged amenorrhea (hypoestrogenic state increases fracture risk).