Why has my TSH risen?

I've been taking Levothyroxine for the past 11 months. My TSH was 7.2 (0.30-4.2) & my FT4 was 11.5 (12.00-22.00).

After almost 8 weeks on 50mcg my TSH went down to 2.8, range as above. My FT4 was not tested this time.

After a further 8 weeks on the same dose my TSH was 2.6 and my FT4 was 14.9.

My GP agreed to increase the Levo to 75mcg and when I tested next after 8 weeks my TSH was at 1.1.

I have now been taking 75mcg for just over 5 months. I decided to do a medichecks home test this week to see how things are doing & I got the following results:

TSH 2.41 (0.27-4.20)

FT4 16.5 (12.00-22.00)

FT3 4.36 (3.10-6.80)

Are there any obvious reasons at to why my TSH has risen? I have taken my blood tests at the same time, fasting, drinking only water.

I have been supplementing B12, B complex & iron for the past 11 months as these were low.

I can't see that I'm doing anything differently but I'm not getting the same results from my current dose. Is this normal? Can anyone help?

I was tested for TPO antibodies last December & these came back negative.


10 Replies

  • How are you feeling? If your symptoms are re-emerging, then you could need an increase in dose. Your TSH is a brain hormone and it has risen because there is not enough thyroid hormone in you blood stream. Your free T3 is a bit on the low side.

  • I've been feeling ok. So much better than I did a year ago. I was hoping to start exercising & trying to sensibly lose some weight. I'm worried now that I might soon start to feel worse again!

  • There are two types of antibodies in people with hypothyroidism, and either one could be positive on its own or both could be positive, or both could be negative. The other antibodies are Thyroglobulin antibodies :


    You might have positive Tg antibodies but negative TPO antibodies.

    Another point is that antibody numbers fluctuate all the time. A negative result is not conclusive. Repeating the test the following week could give a positive result. A positive result is conclusive however. Hashimoto's Thyroiditis (autoimmune hypothyroidism) doesn't get better just because the antibody numbers are temporarily in range.

    So, variations in thyroid function tests, assuming that all other conditions are kept as similar as possible, is likely to be due to fluctuations in antibody numbers, even if you aren't aware that you have them.

    Apparently about 90% of hypothyroidism in the UK and the US is caused by autoimmune hypothyroidism, so it isn't rare.

    Another thing that can cause fluctuations is non-thyroidal illness. Have you been ill recently?

  • No I haven't been unwell recently. I'm aware of the two types of antibodies and I believe the NHS is reluctant to test for TG antibodies. I would be happy to pay for a private test but wasn't aware that you could test positive so quickly after testing negative. It sounds like choosing the best time for the test could be a lottery😂

  • I have been supplementing B12, B complex & iron for the past 11 months as these were low.

    Have you ever had iron re-tested? Going 11 months without a re-test could be dangerous, unless you are taking an extremely small dose, were low to start with, and don't absorb iron well.

  • Yes my ferritin was low to begin with 55 (13.00-150)

    It was retested 6 months ago and had risen to 61 (13.00-150)

    I'm taking a gentle iron as I'm not sure I would get on with much more.

  • jane-c Did you do the Medichecks test first thing in the morning, overnight fast and leaving off Levo for 24 hours? Always advised to do this every time any thyroid tests are done, it ensures the highest possible TSH each time, and if conditions are the same every time then results can be compared accurately.

  • Yes I did the test exactly as you have described. Thanks to this forum I have been taking all my tests like this.

  • You must also stop your B complex tablets at least 4/5 days before testing (I stop all my supplements) as they contain biotin which can give false thyroid blood test (and other tests) results.

  • Thanks for this. I did not (or never have) stopped my supplements. I really wasn't aware I needed to for TSH. Will do so in the future.

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