Should I take medication before thyroid blood t... - Thyroid UK

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Should I take medication before thyroid blood test?


Hi I have been advised not to take my normal dose of levothyroxine before my thyroid blood test tomorrow morning as well as my other medication.

However I am worried that if I don't take my sodium valproate, venlafaxine, oestrogen HRT or fenofibrate beforehand then it will not show on the test if they affect my thyroid in any way, because I have read that they do. Can anybody advise me what I should do?

Many thanks.

10 Replies

No, don't take your medication. It shows up in the blood and lulls the doctors into a false sense of security.

I don't know if you need to eat with the other meds, but ideally you would fast before the test, and have it as early as possible, and BEFORE taking your thyroxine.

Hawkwind in reply to Ruthi

Thank you very much Ruthi, I will follow your advice.

Definitely not you will get a false reading even if you have to leave meds off for most of the day

Hawkwind, take Levothyroxine after the blood draw. I don't see why you shouldn't take your other medications as normal. It's Levothyroxine taken before the blood draw which may skew results by giving a false high FT4.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

Yes, only your thyroid meds need leaving off. Hopefully you dont normally take the thyroid meds alongside everything else do you? Really you need thyroid meds on their own, 4 hours away from everything else and with a glass of water, on an empty stomach.

g x

Blood tests only measure what's in your blood, not whether it works. DON'T take thyroxine before a blood test!!

You take oestrogen HRT? Oestrogen directly interferes with thyroid function. I can't quite believe the oestrogen industry is still able to sell oestrogen HRT after all the lies and fraud.

I recommend you read The Rise and Fall of Estrogen Therapy by Carla Rothenberg

Some people really are oestrogen deficient. I am, and had really bad vaginal atrophy and incontinence because of it - at 49. Of course, horse pee isn't the way to get oestrogen: I'd always suggest bioidenticals, but fake progesterone is even worse for the health.

I am not denying your symptoms and I can see why supplemental oestrogen would appear to help. But oestrogen deficiency is just another myth that helps the oestrogen industry sell the stuff. It's a bit like saying..... Some people are arsenic deficient.

Taking oestrogen will give you osteoporosis and cancer, just to name a couple of diseases. The best source I've found to understand oestrogen, is Ray Peat (PhD in biology). He has plenty of free articles online and isn't selling anything.

Good luck.

Well, I did have DCIS and now it seems that I don't. I don't have osteoporosis, and I'm no longer suicidal and can manage to work, which I couldn't before taking bioidentical hormones. So I think I'll go along with what my endo says. At least some of the money is going to a doctor and a compounding pharmacy in England rather than big pharma. I know how I felt before and how many other things I tried for nearly 7 years, and how I feel now. I'd rather have a short functional life than a longer, miserable one.

Of course, the amount of estrogen I take is about 1/50 of the amount of progesterone and 1/6 of the DHEA.

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