Thyroid meds and menstruation change.

I take minimal thyroid meds of .25 levothyroxine. Since starting this med. I have had a hormone dysfuntion,a 2cm increase in an uterine fibroid. after an injection kickstart. All menstruation irregular since and now I think my menses are nonexistent. All begun in May. I did a pregnancy test and negative. Do I need a hormone level test at the gynocologist or do I need to review my thyroid meds? Normally my periods were 21days apart regular for the last 5 years. Please can you help? I don't want to give blood where I don't need to. Thank you Rusalka

[Machelle Seibel, MD]

A. It was good you did a pregnancy test.  That is a common cause of unusual menstrual flow.  Many other hormones can also affect your periods. To understand the problem, most doctors will check several hormone levels because the values help tell where the problem is located. The most common hormones checked are LH, FSH, and prolactin.  TSH (thyroid stimulating hormone) is another one to check. You are on a low dose of thyroid medication and it should not affect your fibroid and it should not have caused your periods to become irregular. However, if your fibroid is growing, you could have an increased amount of estrogen being made by your body. If your periods are off for reasons other than thyroid, taking thyroid medication won