The LH/FSH Ratio in PCOS

LH and FSH work hand-in-hand: LH drives ovulation, while FSH stimulates eggs for ovulation. A normal LH to FSH ratio is 1-to-1 in women who are premenopausal. But with a condition such as polycystic ovarian syndrome (PCOS), which affects an estimated 5 million American women, FSH levels may be low -- with a ratio of LH to FSH of 2-to-1 or 3-to-1 [source: The National Women's Health Information Center; American Association for Clinical Chemistry].

What causes high FSH levels?

There's a range of normal FSH levels depending on your age and whether you're male or female. Adult males usually have 1.5 to 12.4 milli-international units per milliliter (mIU/ml) circulating throughout their bodies. Adult females who are premenopausal have 4.7 to 21.5 mIU/ml depending on the person and where she may be in her monthly cycle [source: National Institutes of Health].

To find out how your levels measure up, there are both FDA-approved, at-home tests and laboratory tests that are performed in your doctor's office (at this time, however, at-home FSH testing isn't available for men). The at-home version is similar to an at-home pregnancy test -- on a certain day of her monthly cycle (FSH is typically tested on day 3), a woman urinates on a test stick. Laboratory testing is a simple blood test, also on day 3, and is often done in conjunction with testing the levels of other related hormones, specifically LH, to pinpoint if there's a problem with the amount of hormone the body is producing.

Abnormal levels of FSH, low or high, may be caused by autoimmune disorders, such as Graves' disease (an overactive thyroid), genetic conditions such as fragile X, or conditions affecting the endocrine system such as polycystic ovarian syndrome.

Elevated FSH levels are a good indication that a woman's egg supply is diminishing, or diminished. Age is the No. 1 indicator that a woman will have high FSH levels. Typically, FSH levels begin to rise naturally about 10 years before a woman enters menopause, and postmenopausal women may have levels of FSH that fall between 25.8 and 134.8 mIU/ml [source: National Institutes of Health].

What's happening here is that the body is always trying to stimulate eggs, long after a woman's egg supply is spent. High FSH is absolutely normal in postmenopausal women. High FSH in premenopausal women, however, may be caused by problems such as a pituitary gland disorder or chemotherapy and radiation treatment. Let's find out what, if anything, can be done to lower FSH levels when they've become too high.