FSH/Tamoxifen

My doctor is wanting to switch me to Arimidex so has ordered an FSH test to determine if I am post menapausal.  Can the Tamoxifen I have been taking skew the test results?  Thank you.
Crystal

[CCF-RN,MSN-JS]

Dear Crystal, Determining whether you are in menopause by the FSH level is a bit tricky.  Menopause is a process and there are a lot of fluctuations in not only the estrogen levels but also in the FSH, it can be high at one time and low a month later.  Usually if a person has really gone into menopause (stopped menstruating for several months) the FSH tests are a little more useful.  But even then, it's not 100 percent accurate.   Having said that, the tamoxifen may have some effect on the FSH in terms of effecting levels of circulating estrogen, but probably not enough to make a difference in the interpretation of the results.