Thyroid UK
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Underactive Thyroid and Periods


I was wondering if anyone knew much about the issues you can have with your periods due to thyroid problems. I have always been regular with my periods never being more than a day late or early. However my last period was 6 days late, that finished just over a week ago and today I have started my period again so I am now very early. I shouldn't have started for another two weeks yet. This is unknown of for me. Does anyone understand why this is happening. Is it linked to my thyroid?

I was diagnosed with an underactive thyroid two years ago. My bloods are currently a little strange as my T4 is increasing but so is my TSH. So my doctor upped my dose to 100mg from 75mg last week. My current levels are:

TSH- 8.5 (should be under 4.5)

T4- 21 (range was 10-21)

Any help would be greatly appreciated.

5 Replies

Looks to me like you could have a conversion problem - have you had all your vitamins tested as, without your vitamins being at optimum levels for a thyroid sufferer, this could mean your body is not able to use your thyroid medication properly.

Sorry also meant to say that until your thyroid medication is right then your periods will be erratic.

Moggie x


Female problems are associated with hypothyroidism. I am not surprised your have symptoms as your TSH was 8.5. Obviously you haven't been given regular thyroid gland blood tests.

Have another blood test in about 6 weeks to make sure your TSH is coming down and if it is still on the high side, ask for another increase.

If you email (she has been ill and may still be off) and ask for a copy of the Pulse Online article by Dr Toft ex President of the British Thyroid Association wherein he recommends a low or even suppressed TSH and give a copy to your GP highlighting question 6.

Quite a few women who have been undiagnosed due to the reliance on the TSH or on too low a dose, have undergone unnecessary hysterectomies in the past.

1 like

When I was under -medicated I had pretty much everlasting periods. As above the most sensible answer is to get the thyroid medication right. Even after doing this (or so I thought at the time)I was still experiencing long, heavy periods and other issues. I opted for an endometrial ablation under anaesthetic using Novasure (the womb lining is removed) which I found no more painful than period pain and from which I recovered very quickly. I don't get periods now even though I am still 5 years or so off menopause (some people still get light ones) but still get the pain once a month - no identified side effects 6 months later . Only suitable for those who have finished with having children as it is no longer safe to be pregnant as the womb lining isn't thick enough. Thought I would mention it in case anyone was reading this question and at the point of having hysterectomy as it is a much less drastic option which leaves the womb etc. in place.


How long did it take you all to get your thyroid medication right? I find it strange because I feel 100% better in myself since I was diagnosed except I have developed irritable bowel syndrome and now the irregular periods. I find it strange because I never actually had these symptoms prior to be diagnosed but the symptoms I did have prior to diagnosis have more or less gone. Has anyone else experienced this?

I have been getting thyroid function tests every 8 weeks or so and my TSH is just slowly increasing along with my T4 which I think is concerning and I am going to talk with my GP to see if I can get a T3 test done as well.

I am 22 and have not had children yet so I would try and avoid anything that would prevent that but hopefully things will get sorted soon or I would probably consider it.

Thank you all for your comments it really does help :)


I think its your T4 that you should be concerned about - its a the top of the range so your GP will be unlikely to increase your meds further which is why I said that I don't think you are converting the T4 you are taking into the T3 your body needs, your T4 is just pooling in your blood and is unable, whether it be due to lack of vital vitamins or something else, to process on to the next step. A FT3 test will certainly tell you if, in fact, this is the case.

Moggie x


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