Increasing thyroxine and blood tests: Hi, I'm... - Thyroid UK

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Increasing thyroxine and blood tests



I'm fairly new here!

I was advised by GP, after TSH test result, to increase Thyroxine from 100 to 150 3 weeks ago, and to increase from 150 to 175 1 week ago. GP wants me back for repeat TSH test 6 weeks after I started the increased dose.

I know they won't do the full test so have ordered a Medichecks kit and was going to get the blood sample taken this coming week. But just wondering... Is there any point in me having a private test done given than I am in the middle of increasing the Thyroxine dose?

I am also taking lots of Thyroid support supplements prescribed by a naturopath. Not sure if they will affect the test?

From reading other posts, I realise I need to get blood sample taken early am., having fasted overnight and drink only water. But should I NOT take the supplements or Thyroxine before the blood sample?

I am suffering from exhaustion, massive weight gain, hair loss, insomnia, etc etc and definitely want to see an endocrinologist once I have the full test results.


12 Replies

There's no point in testing, privately or with your GP, until 6-8 weeks after a dose increase. As you're going to do both, you could do them ​the same morning and it would be good to see how Medichecks compares to your NHS test (accurately one would hope!). That could be very useful in the future if you do a private test and your doctor dismisses it.

Levo should be left off for 24 hours when testing, so take that day's dose after the blood draw.

What does your thyroid support supplement contain? Hopefully not iodine as that shouldn't be supplemented unless tested and found to be deficient.

If it contains B vitamins, check to see if Biotin (B7) is included. If it is leave the supplement off for a few days as Biotin skews results.

Hi thanks so much SeasideSusie. Really helpful reply.

It would be good to have the tests done on the same day but I have to travel to Glasgow for the Medichecks test and can't do that on the same morning as GP surgery.

Supplements do have iodine in them, but don't have B7. I will ask naturopath about the iodine content. He has prescribed it before and I've been fine with it, but now you've said that I will definitely check.

I'll wait 6 weeks from when I went up to 175 before I go for tests.

Many thanks again.

SeasideSusieAdministrator in reply to Islander23

Not sure if you have been tested for thyroid antibodies and have Hashimoto's, but if you have then supplementing iodine can cause problems with Hashi's flares (antibodies attacking).

Iodine used to be used to treat hypERthyroidism.

Thanks. Yes I do have Hashimotos. Am talking to naturopath about iodine now.

humanbean in reply to Islander23

If you do a finger-prick test you can do it at home, no travelling required. All you'll have to do is take the package to the post office.

Islander23 in reply to humanbean

Thanks! I wasn't sure if I'd produce enough blood for the test with a finger-prick.

humanbean in reply to Islander23

Ask for advice on here on the best way of getting enough blood doing finger-prick testing. There's a lot of experience amongst the members here. And the companies that do finger-prick testing do send out instructions and suggestions on how to do it successfully.

If you really want to do a test using a venous blood sample, then it can be arranged, but you would need to know who will take blood for you.

Blue Horizon make several suggestions (at various costs), but their website seems to be down at the moment, so I can't link you to it.

Islander23 in reply to humanbean

When I bought the test kit online from Medicheck it suggested venous blood sample, so I thought I would be better not risking finger-prick in case I didn't get enough blood. Hence the need to travel to Glasgow for the test!

humanbean in reply to Islander23

It depends on which test you are going to do. If it is the group of tests with 11 tests included then there are plenty of people who do the test successfully with finger-prick sampling.

But equally, there are some people who never manage to get enough blood for all the tests.

If you are the kind of person who clots very quickly when they cut themselves then perhaps venous is best.

I would be asking for urgent referal to an Endocrinologist NOW. Especially if you have not seen one yet.

Have you ever had an Ultrasound scan of your Thyroid?


Thanks. I'm looking into which endo to go to at the moment.

I would definitely wait six weeks before running new labs with every new dose change for T4 . I would also recommend that you ask your Dr for some low dose T3/NDT . Adding some nutrients would be a great help like Vit."D" Selenium , B-12 , good multi vit. Vit."C" good fish oil , Iron , Magnesium ,Calcium . Iron and Calcium are needed to be taken at least 4hours apart from thyroid meds . I would suggest that you ask your Dr to run labs on your Vit"D" levels , Iron/Ferritin , B12 .

When running labs for Iron/ferritin levels Iron needs to be stopped 5-7 days prior to testing .

Wishing you success .

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