High TSH, normal T4 - what next? : Elevated TSH... - Thyroid UK

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High TSH, normal T4 - what next?

ThyroidLadyLondon profile image

Elevated TSH (15-18), normal mid range t4. A poll please for those that have been in that position:

A) were you symptomatic?

B) what was the advice of your doc?

Thanks in advance for your views!

(Puppies for attention =))


11 Replies

Always best to give the exact numbers: results and ranges. Normal just means in-range, which isn't always that good.

If your TSH is that high, you should be on thyroid hormone replacement, because your thyroid is really struggling to produce that amount of hormone.

Already on levothyroxine.

TSH - 17.29

T4 - 17.4

As I said, we also need the ranges. They vary from lab to lab, so we need the ranges that went with your results.

If you are already on levo, then you are grossly under-medicated to have a TSH that high. It should come down to 1 or under.

But the t4 is optimal. Adding more synthetic t4 will make me overmedicated, no?

Who said the FT4 was optimal? I would very much doubt that it is. Difficult to tell without the range (please add it) but it looks as if it could be mid-range, and most hypos need it a lot higher than that. Optimal is more about how you feel than a number on a page.

I'm pretty sure you can add 25 mcg levo without sending the result over-range. But, even if you did, so what? T4 is basically the storage hormone, that needs to be converted into the active hormone, T3. You're only over-medicated if your FT3 is over-range.

shaws profile image
shawsAdministrator in reply to ThyroidLadyLondon

If you can add the ranges, you can press the down arrow next to 'More' and select edit and insert ranges.

SlowDragon profile image

Low vitamin levels are extremely common and can cause high Ft4 and low Ft3

If you took levothyroxine within 24 hours of blood test this will cause false high Ft4

For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested. Also EXTREMELY important to test vitamin D, folate, ferritin and B12

Low vitamin levels are extremely common, especially if you have autoimmune thyroid disease (Hashimoto's) diagnosed by raised Thyroid antibodies

Ask GP to test vitamin levels

You may need to get full Thyroid testing privately as NHS refuses to test TG antibodies if TPO antibodies are negative

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .

Last dose of Levothyroxine 24 hours prior to blood test. (taking delayed dose immediately after blood draw).

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

Is this how you do your tests?

Private tests are available. Thousands on here forced to do this as NHS often refuses to test FT3 or antibodies


For thyroid including antibodies and vitamins

Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have special offers, Medichecks usually have offers on Thursdays, Blue Horizon its more random

If you can get GP to test vitamins and antibodies then cheapest option for just TSH, FT4 and FT3 £29 (via NHS private service )


The aim of Levothyroxine is to increase the dose slowly in 25mcg steps upwards until TSH is under 2 (many need TSH significantly under one) and most important is that FT4 is in top third of range and FT3 at least half way through range

NHS guidelines on Levothyroxine including that most patients eventually need somewhere between 100mcg and 200mcg Levothyroxine.


Also what foods to avoid (eg recommended to avoid calcium rich foods at least four hours from taking Levo)

All four vitamins need to be regularly tested and frequently need supplementing to maintain optimal levels

But half life of levothyroxine is more than 24 hours, so what difference will it make not to take it for 24 hours before bloods?

SlowDragon profile image
SlowDragonAdministrator in reply to ThyroidLadyLondon

If you take levothyroxine before blood test you get false high Ft4

Always take last dose 24 hours before blood test

SlowDragon profile image

Love the puppies 🐶

I reeeeally want a cocker spaniel pup =) I think I googled them a while back which is why I had a pic on my phone =) dogs reduce stress levels, I’m pretty sure that’s been shown in many studies, so I think it would be a health benefit if anything =))

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