Research for effects of insufficient Levo starting dose

[N5girl]

Hi

Quick recap: Endo started me on 25 mcg of Levo following an ultrasound showing a Hashi thyroid and increasing TSH.

It has been a week now and I feel ghastly. I had zero expectations of feeling better quickly, but definitely didn’t think I would be dosing off during meetings or feeling unsafe to drive.

I asked the Endo (via PA) for a revised dose, ie 50 mcg. Response back has been to stay on 25 mcg for six weeks. I am due to speak to them tonight as this is not feasible.

I read on here that Levo replaces the thyroid hormone, it doesn’t top up what your body makes itself. My gp said the same thing this morning and said it would explain why I feel so dreadful on just 25 mcg.

Does anyone have a link to any research or sites that evidences Levo being a replacement, not a top up? I would like to read as much as possible before I speak to the Endo again.

Also, I assume that for most people the regular starting dose of 50 is quite close or above what they currently are producing. So they are either no worse on 50 or get symptoms similar to being over-medicated?

[jimh111]

Levothyroxine tops up your thyroid hormone levels but as they go up TSH falls and so the thyroid may secrete a little less. If your thyroid is functioning reasonably normally and TSH not high then levothyroxine will not top up your levels. If your thyroid is in a bad way then levothyroxine will top up your levels.For people over 60 or with cardiac problems the recommendation is they are started on 25 mcg. Younger people tend to be started on 100 mcg nowadays if their fT4 is low. The idea is this will speed up recovery. I have seen a study which found starting on 100 mcg levothyroxine did not give any benefit but that was some time ago and I've lost the reference.

Even if you are on an optimal dose it will take several months to recover. Many effects of thyroid hormone take months to feed through.

[Obsdian]

I can't answer most of what you asked but can share my experience.

I was started on 50mcg back in September 2023. I didn't feel worse but neither did I feel enough improvement to call "better". Only just this week managed to talk them into a dose increase.

[humanbean]

You might find something of use in the NICE Guidance on thyroid disease :

nice.org.uk/guidance/NG145

There is also the CKS - Clinical Knowledge Summary on Hypothyroidism which you might find easier to read than the guidance. Theoretically the two links should 100% agree with each other but I've never compared the two.

cks.nice.org.uk/topics/hypo...

[N5girl in reply to humanbean]

I was told v firmly that all the Endo’s patients are started on 25mcg and most do not go beyond that dose. This seems to be the complete opposite of what the dosing guidelines, my GP say. There was an extreme focus during the conversation on the effects of over medication. I have zero symptoms of this.

Bloods were taken on Friday (a week after I started) and will be reviewed on Monday. I am not sure what they will show given the extended half life of Levo. I get the impression from the conversation that any decrease in TSH will be taken as evidence that the original dosing decision is correct. TSH not falling will be taken as evidence that Levo is not the correct treatment (which is possible). I don’t see a scenario in which it is acknowledged that an inadequate Levo dose is the culprit for the extreme fatigue I have experienced thus week.

All in all, this has been v disconcerting and I don’t know what to think.

[humanbean in reply to N5girl]

The idea that somebody who is hypothyroid would be over-dosed on 25mcg of Levo is absurd. Doctors will usually prescribe 25mcg as a starting dose for children and the elderly. The definition of elderly is variable, depending on the doctor, but is usually over 60 (?)

Bloods were taken on Friday (a week after I started) and will be reviewed on Monday. I am not sure what they will show given the extended half life of Levo. I get the impression from the conversation that any decrease in TSH will be taken as evidence that the original dosing decision is correct. TSH not falling will be taken as evidence that Levo is not the correct treatment (which is possible).

That looks like a complete perversion of the guidelines. Nobody should ever be tested after just a week.

Have you been diagnosed with overt or subclinical hypothyroidism? Do you have a copy of your results and reference ranges from before your diagnosis?

[humanbean in reply to humanbean]

I forgot to ask... Which country do you live in? And are you under 60 or 60+?

[N5girl in reply to humanbean]

50 and in the UK. I was surprised by the test too - I thought it was just going to be a check on my Vit D level post the loading programme. I don’t think it was intentional as the Endo didn’t know that they had asked for TSH/FT4.

[N5girl in reply to humanbean]

A few months ago my rheumatologist referred me to an Endo because of blood test results re thyroid. This was after ruling out RA following a high inflammation score and v sore joints. Endo decided on an ultrasound following a physical exam and more blood tests. Radiologist said scan showed Hashimotos. The radiologist said they wouldn’t treat it in the NHS so it must be mild. I don’t have the ranges, just the scores from the letter. TSH 3, T4 13, T3 4. It also says I am TPO antibody positive. I am tested annually for a work medical and TSH has been increasing, T4/T3 falling over the last few years . Endo decided to prescribe because of the scan results, a family history of Hashimotos, and my symptoms (I have all the usual ones apart from constipation). She said the lab results were borderline.