Progestin Challenge Test for Amenorrhea
For diagnosing the cause of amenorrhea, administer medroxyprogesterone acetate 10 mg orally daily for 5-10 days, or progesterone in oil 200 mg intramuscularly as a single dose. 1, 2
Purpose and Interpretation
The progestin challenge test assesses endogenous estrogen production and the patency of the outflow tract:
Positive withdrawal bleeding (occurs within 2-7 days after completing progestin) indicates adequate estrogen levels, a functional endometrium, and patent outflow tract, suggesting anovulation as the cause (most commonly polycystic ovary syndrome or hypothalamic dysfunction) 1, 2
Negative withdrawal bleeding (no bleeding after progestin) indicates either hypoestrogenism or anatomic obstruction of the outflow tract, requiring further evaluation with an estrogen-progesterone challenge test 2, 3
Dosing Regimens
Oral medroxyprogesterone acetate: 10 mg daily for 5-10 days is the standard regimen 1, 2
Intramuscular progesterone: 200 mg progesterone in oil as a single injection can be used as an alternative 2
Clinical Context and Caveats
This test should only be performed after pregnancy has been excluded with a pregnancy test, as pregnancy is the most common cause of amenorrhea in reproductive-age women 4, 2, 3
The progestin challenge is part of a systematic diagnostic algorithm, not a treatment. Initial laboratory workup should include pregnancy test, luteinizing hormone, follicle-stimulating hormone, prolactin, and thyroid-stimulating hormone levels 4, 3
Important Pitfall
Do not confuse the diagnostic progestin challenge test with cyclic progestin therapy for treatment, which uses medroxyprogesterone acetate 10 mg daily for 10-14 days each month to induce regular withdrawal bleeding in patients with chronic anovulation and prevent endometrial hyperplasia from unopposed estrogen 1, 2