Can FSH Levels Accurately Reflect Menopause in Women Taking Oral Contraceptives?

Patricia (Pat) A. Camillo, PhD, RN, APRN-BC

Disclosures

April 20, 2006

Question

Will a blood sample for follicle-stimulating hormone (FSH) and luteinizing hormone (LH) be accurate for a woman, age 50, who is on birth control pills, if it is drawn during the week of hormone-free pills?

Response From the Expert

Patricia (Pat) A. Camillo, PhD, RN, APRN-BC 
President and CEO, Allwise Publishing Incorporated, New York, NY

 

 

It is commonly believed that lower estrogen levels account for the rise in FSH that coincides with menopause. Therefore, obtaining a simple serum FSH or LH should reveal whether a woman is menopausal. However, there are few studies to support this recommendation, and more recent data confirm that changes in FSH occur earlier in the perimenopausal transition, during the late reproductive years.[1]

FSH is not regulated by estrogen. As the number of follicles diminishes, inhibin (an ovarian hormone) declines, stimulating a rise in pituitary FSH via a classic negative feedback loop.[2] Rising FSH stimulates the remaining follicles to increase (rather than decrease) the estrogen level during the late reproductive years. All of this can occur 2 to 3 years prior to the last menstrual cycle.[3,4,5]

Since it isn't possible to predict when a woman will naturally move into menopause, obtaining an FSH at age 50, without menstrual cycle data to support a suspicion of menopause, could result in very misleading information. Furthermore, studies suggest that an FSH level drawn during the "pill-free" period from a woman taking oral contraceptives (OCs) is not a reliable marker of menopause.[6,7]

Oral contraceptives are significantly more potent than the estrogens used for relief of hot flashes during menopause; these less potent estrogens do not provide reliable contraceptive control. A careful evaluation of the patient's personal and family health history should be conducted annually to determine whether she should remain on OCs, regardless of her FSH or LH level. A conservative approach would be to stop OCs at age 50, switch to a barrier method, and await the natural cessation of menstruation. This would provide the most reliable determination of menopausal status.

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