Can b complex with biotin cause elevated T4?

[Pinkpetite]

Hello, I had to have a thyroid blood test due to imminent surgery so only had 3 days notice. I had stopped my b complex (PinkTribe liposomal b complex) 3 days before the test. The result of the T4 was 25 (11 - 21) whereas the test I had about 3 weeks ago at my Gp, when I had stopped the b complex, was well within the range at 16 (9 -23) - different hospitals hence different ranges. The only other different thing I was doing was low carb for the last 2 weeks - could this have elevated my T4? I had had a coffee before both tests, no milk, and before the second test had been noticeable anxious - just wondering if this then correlates to the increased T4?

Would it be advisable to get another test done to just check again, probably at the original hospital where the result was 16?

[Jaydee1507 Administrator]

What was the timing of your last dose of Levo before each test? That alone may explain the difference if you had a test close to taking Levo.

3 days should be enough for biotin not to affect your results. Its not a huge amount of biotin in a B complex.

Low carb can change blood results. Perhaps retest if its important regarding dose and be sure to allow 24hrs from last dose of Levo and 4-7 days off B complex.

[Pinkpetite in reply to Jaydee1507]

Thanks, it was 24 hrs after my last dose of thyroxine. Actually about 3 months before I had lowered my dose myself (to 112.5mcg), under pressure from the GP due to my constant low TSH 0.01 (0.3 - 4.2 ), and had just gone back to my original dose 125mcg for about 2 weeks so I'm now wondering if it was this adjustment and things hadn't settled. My TSH has been 0.01 consistently for about 15yrs and they have checked my heart with a scan and my pituitary and everything is ok.

However I do feel better on low carb, and if I can sustain it (it is a bit restrictive), it might be that I do need a lower dose of thyroxine. My T3 was 4.3 (2.4 - 6) on the 112.5mcg before I started the low carb and my T4 16 (9 - 23) as previously mentioned.

[Sleepman in reply to Pinkpetite]

What time of day were bloods done as results change with time of day?I was on low carb before thyroid and felt good on it. Later found put I was gluten intollerant and los carb stopped me having gluten. The wisecones advise if autoimmune underactive more chance you cannot tolerate gluten.

[Pinkpetite in reply to Sleepman]

Test was about 11am as it was part of a pre op assessment and not planned. And yes I avoid gluten as much as possible. I think I'm better on low carb due to my blood sugar sensitivity which I read often comes with an underactive thyroid.

[Jaydee1507 Administrator in reply to Pinkpetite]

So its likely that having increased your dose only 2 weks previously then thats why the numbers look strange.

Suggest retesting 6-8 weeks from when you increased back up.

[Pinkpetite in reply to Jaydee1507]

Yes OK I'll retest in 8 weeks. Thanks.

[helvella Administrator]

To clarify, especially for any future readers, biotin does not increase the actual T4 levels in your blood.

Biotin can interfere with some lab tests, including some but not all TSH, Free T4 and Free T3 assays, such that the results become unreliable.

Other than when taking very large doses of biotin, at least many milligrams, the effects can be seen but are not that great.

[Pinkpetite in reply to helvella]

Thanks for the explanation.

[Pinkpetite in reply to helvella]

Can I just ask do my results look ok from the 112.5mcg dose? Actually it was 125mcg 4 days and 100mcg 3 days weekly.

[helvella Administrator in reply to Pinkpetite]

I rather agree with the re-testing in a few weeks.

When anything changes, it can take a while for the blood test results to reflect the changes - whether low carb or change of dose.

[Pinkpetite in reply to helvella]

I changed the dose just for 8 weeks, had the first test and then went back up to 125mcg daily.