Thyroid UK

Blood tests and meds

Hi all,

I was diagnosed last year with an under active thyroid and since then have been reading up a bit as I wasn't really given any information on it.

My main question is: I am due for a blood test tomorrow and I wondered am I meant to take my levo as normal? (I take it first thing) Or should I wait until after the blood test? Does it make a difference?

I've been feeling lousy again - dizzy spells, exhausted, forgetful and brian fog so she is having a look at my thyroid, B12, and vit D. She's also rechecking my iron level, as apparently that was borderline at my last lot of tests in Feb.

7 Replies

Wait until after the blood test.

Make sure you get your own copy of the results including ranges. Remember the nhs ranges are pretty useless. But unfortunately the nhs disregards symptoms. Iron: for many years i was told i was normal when i was anaemic. You need min ferritin of 90 for good thyroid health. NHS will tell you 20 is normal. You should start takingferrous fumerate immediately i feel - you can buy online without script (get at least the 220mg).

Being hypo affects your ability to absorb iron, so you need to monitor this carefully.


You can also buy ferrous fumarate without prescription from many pharmacists. Boots insist on a prescription so avoid them (so I've read, I've never tested this personally). A box of 84 x ferrous fumarate 210mg is sufficient for 3 tablets a day for 28 days. A box costs less than a fiver from Lloyds and no prescription was required the last few times I've bought them.

Take each iron pill with 500mg - 1000mg vitamin C - it helps absorption. Keep iron 4 hours away from taking levothyroxine.

Edit : If even your doctor is saying your iron is borderline, you are probably very, very anaemic. I would supplement with iron even if your doctor says you are still in range. Get copies of your results and post them in a new question here, including the reference ranges.


Thanks for this.

Humanbean I was just about to ask re taking iron and levo, as I had read that iron supplements have an effect on the absorption of T4.

I'm somewhat annoyed that I wasn't informed that my iron was/is "borderline". I could have tackled this sooner!


Yes, iron can bind to levo in some way. It isn't a subject I know anything about, I just know there is this "4 hour rule"!

Incidentally, some people are very sensitive to iron and vitamin C. Iron bungs people up, and vit C gives them the runs. The ideal is to find a balance which allows people to have a normal life. And if the iron upsets your stomach there are other types of iron supplement that you may tolerate better. Don't just give up on it. :)


humanbean this was very helpful for me too as I've just found out that my iron is on the floor and levels don't appear to be responding to Spatone the way they once did. Now I have to figure out what to do next. What is the next best thing to ferrous fumarate if it gives you a sick stomach?


Okay. Thank so much for the info :-)


When taking supplements take them apart from levo by at least 4 hours.


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