Whats the highest dosage of Levothyroxine you can be prescribed

Ive been on 100mcg of levothyroxine for almost 8 years now. Recently dr tested me for antibodies (see below). I have started to experience leg pain/tiredness, moody, etc. I know for a fact I will finally be diagnosed with Hashimotos! Whats the highest dose of levo you can take before you have to supplement it?

FT4 1.0 ng/dL (0.7 - 1.6 ng/dL)

TSH 3.870 uIU/mL (0.358 - 3.740 uIU/mL)

Anti-Thyroglobulin<20 IU/mL (<40 IU/mL)

Anti-TPO-Ab 335.0 IU/mL (<35 IU/mL)

13 Replies

  • Shereebl, there's no limit to how much Levothyroxine can be prescribed.

    100mcg is insufficient for you as TSH 3.87 is too high and FT4 is low in range. The goal of Levothyroxine is to restore the patient to euthyroid status and for most this will be when TSH is just above or below 1.0 with FT4 in the upper range. Read Treatment Options in thyroiduk.org.uk/tuk/about_... Email louise.warvill@thyroiduk.org.uk for a copy of the Pulse article if you would like to show it to your GP when you request a dose increase.

    TPO antibodies are positive for autoimmune thyroid disease (Hashimoto's). There is no treatment for Hashimoto's but adopting 100% gluten-free diet can help reduce Hashi flares, symptoms and antibodies. Low/suppressed TSH means less stimulation of the thyroid gland which is also helpful in managing Hashi's.

    Ask your GP to test ferritin, vitamin D, B12 and folate which are commonly low/deficient in hypothyroid patients which can cause musculoskeletal pain,fatigue and low mood similar to hypothyroid symptoms.


    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.

  • Not strictly true as 1mg would kill a person that's why it comes in mcg lol.

  • A shame you did not read further responses before posting that.


  • Do bear in mind that it is usual to give 600 microgram doses to healthy volunteers when testing levothyroxine products.

  • CATLOWE30,

    1,000mcg wouldn't kill anyone, Lol!

  • I have been on 125 mg Thyroxine , now i take 100mg Mon-Fri and 125 mg Sat-Sun.

  • One of my neighbours was on 300mcg daily and not 100% well. She moved away so no idea how she's doing now.

  • The other day I posted about a specific genetic reason some people might require a higher than usual dose of levothyroxine. Not easy reading!


    The highest I have read about was something like 3000 micrograms a day - the person showed no signs of being overdosed. You must realise that this is at the unbelievable level - but it is formally documented.

    For you, an increase to, say 125 micrograms, or 100 micrograms one day and 125 micrograms the next would seem a sensible step.

  • You've been prescribed a dose of levo which is far too low for you thus your TSH is too high.

    Before the blood tests and levothyroxine were introduced we were given natural dessicated thyroid hormones and the dose was between 200mcg and 400mcg.

    One doctor, now deceased unfortunately, fought with the Authorities saying that patients were put in parlous situations due to the authorities inability to discuss proper prescribing.

  • I'm on 200 Levo I think u need your dose increased your tsh too high

  • Took this directly from the BTF website:

    "Levothyroxine doses are dependent upon the person’s body weight. Most patients require between 100 and 150 micrograms a day, but the dose can be lower than 75 micrograms or up to 300 micrograms a day, depending on your needs."

    It implies the max is 300mcg daily. That said, I know people on more than that and also I tend to not take the BTF advice as gospel.

    Good question though! One I'll do some more research on now to better understand myself!

  • Perfectly happy to believe it says that on the BTF website. But it simply isn't strictly dependent on weight. Yes, a heavy person is likely to need more than a light person. But that is only a bit of the story.

    I have often quoted the extreme example of a man who was on something like 3200 micrograms day and had no signs of overdosing at all.

    It is well known that absorption is an important variable. Some of us absorb levothyroxine far better than others.

  • I did say I also know people on more than that and its dependant on the individual x just incase you thought I was in agreement with BTF.

    I also have Coeliac so know all too well that absorption is key

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