FSH stands for follicle stimulating hormone, and is one of the more important ways in which the brain talks to the ovaries. Simply, the brain releases FSH when it wants the ovaries to mature an egg; as the ovaries choose and mature the egg, hormone products from the ovaries signal the brain to decrease the release of FSH. This is an example of a feedback loop.
The FSH test is the simplest method we know of in 1998 to test the ability of the eggs to talk back to the brain. If the system is functioning the way it should, then the FSH level early in the cycle should be on the lower end of the scale. How low? That depends on the laboratory doing the testing. Each lab, by nature of the way the test is done there, will report a different level for a given test. One of the great confusions regarding FSH testing is that a similar level means very different things at different places. Also, some clinics characterize their tests very carefully; others less so. FSH is reported in "units" and results from 2 units to 7 are probably normal in just about any lab. Levels above 25 are probably abnormal.
The area between 9-24 may represent normal or abnormal levels, depending on how the test is performed. Adding to the confusion is that FSH bounces around quite a bit. One month the result may be a 7 and the next month may be a 13. For a while we thought that it might be possible to wait for a month with a better level and improve the odds that a given cycle would work. Unfortunately we learned that the intermittent high FSH is as bad a prognostic sign in months where the FSH is normal as in months where it is high.
Full article: Good Eggs, FSH levels and Ovarian Reserve by David Sable, MD
Diagnostic role of follicle-stimulating hormone (FSH) measurements during the menopausal transition--an analysis of FSH, oestradiol and inhibin.
Burger HG Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.
This review examines the role of follicle-stimulating hormone (FSH) measurement in assessing the significance of symptoms and possible continuing fertility during the menopausal transition. Follicle-stimulating hormone measurement is advocated frequently as a useful diagnostic tool in perimenopausal patients. Several investigators have shown that the serum FSH level increases in the early -- mid-follicular and early postovulatory phases in women over the age of 40 years who continue to experience regular menstrual cycles.
The serum oestradiol level may fall (although this is controversial) and the immunoreactive inhibin level falls, being inversely correlated with the rising FSH level. When alterations in menstrual cyclicity or flow commence, signalling the onset of the menopausal transition, FSH levels may change abruptly, rising into the normal postmenopausal range and falling again into the range normally seen in young fertile women. Oestradiol and inhibin generally fluctuate in parallel with each other but inversely to FSH, although at times oestradiol in particular may be increased markedly.
Postmenopausal FSH levels may be followed by endocrine evidence compatible with normal ovulation. After the menopause, FSH levels rise 10-15-fold, with low oestradiol and undetectable inhibin levels. It is concluded that FSH measurement is of little value, if any in the assessment of women during the menopausal transition because it cannot be interpreted reliably and because, apparently, ovulatory (and, presumably, potentially fertile) cycles may occur subsequent to the observation of postmenopausal FSH levels. Both oestradiol and inhibin are important negative feedback regulators of circulating FSH.
Source: Diagnostic role of follicle-stimulating hormone (FSH) measurements during the menopausal transition--an analysis of FSH, oestradiol and inhibin.
First Photo credit: Fertility test Photographic Print, by Science Photo Library on Amazon.com
Second Photo credit: Follicle Stimulating Hormone (FSH) Midstream Tests on Amazon.com
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