T3 test: I've been taking 100mcg Levothyroxine... - Thyroid UK

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T3 test

Blobby1234 profile image
Blobby1234
•10 Replies

I've been taking 100mcg Levothyroxine for Hashimotos for years. Over the last year my TSH has been coming back 0.02. My GP dropped the dose to 75mcg two months ago and now TSH is 3.8 🙄 (ref range 0.2-4) . She finally agreed to do a T3 test and that has come back as 1.2 nmol/l ("normal"). According to the reference range, the bottom of T3 normal is 1.1, so I wouldn't call it great. I suspect she isn't the world's leading expert in endocrinology and didn't seem to understand my questions around the leaping about of the TSH, any possible link between that and T3 and she didnt test FT4 anyway. I could get a private test but not much point if I'm taking the results to someone a bit clueless. Fwiw I can't say I noticed much subjective difference from dropping the Levo dose apart from hair loss.

Any interpretations of the results here? How does TSH affect T3? Ta in advance!

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SlowDragon profile image
SlowDragonAdministrator

Contact GP and request/insist that you return to 100mcg levothyroxine

TSH is far too high and Ft3 too low

The aim of levothyroxine is to increase dose upwards in 25mcg steps until TSH is under 2

When adequately treated, TSH will often be well under one.

Most important results are ALWAYS Ft3 followed by Ft4.

When adequately treated Ft4 is usually in top third of range and Ft3 at least 60% through range (regardless of how low TSH is)

Extremely important to have optimal vitamin levels too as this helps reduce symptoms and improve how levothyroxine works

guidelines on dose levothyroxine by weight

Even if we don’t start on full replacement dose, most people need to increase levothyroxine dose slowly upwards in 25mcg steps (retesting 6-8 weeks after each increase) until on, or near full replacement dose

NICE guidelines on full replacement dose

nice.org.uk/guidance/ng145/...

1.3.6

Consider starting levothyroxine at a dosage of 1.6 micrograms per kilogram of body weight per day (rounded to the nearest 25 micrograms) for adults under 65 with primary hypothyroidism and no history of cardiovascular disease.

Also here

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

gp-update.co.uk/Latest-Upda...

Traditionally we have tended to start patients on a low dose of levothyroxine and titrate it up over a period of months. RCT evidence suggests that for the majority of patients this is not necessary and may waste resources.

For patients aged >60y or with ischaemic heart disease, start levothyroxine at 25–50μg daily and titrate up every 3 to 6 weeks as tolerated.

For ALL other patients start at full replacement dose. For most this will equate to 1.6 μg/kg/day (approximately 100μg for a 60kg woman and 125μg for a 75kg man).

If you are starting treatment for subclinical hypothyroidism, this article advises starting at a dose close to the full treatment dose on the basis that it is difficult to assess symptom response unless a therapeutic dose has been trialled.

BMJ also clear on dose required

bmj.com/content/368/bmj.m41

bestpractice.bmj.com/topics...

Blobby1234 profile image
Blobby1234• in reply toSlowDragon

Thank you. But on 100mcg my TSH is always to low and 75 always too high. GP response has always been take a 25 every other day and after 2m always ends the same. Too high or too low.

ilenuca profile image
ilenuca• in reply toBlobby1234

Try 88 mcg every day

SlowDragon profile image
SlowDragonAdministrator

Request firmly that GP test vitamin D, folate, ferritin and B12

These are frequently very low when dose levothyroxine has been inappropriately reduced

Blobby1234 profile image
Blobby1234• in reply toSlowDragon

Would that make a difference to TSH/T3? I take a D3 and MultiB every day. Have done for 10 yrs.

SlowDragon profile image
SlowDragonAdministrator• in reply toBlobby1234

Multivitamins are never recommended on here

Too little of what we do need and stuff you don’t want

Always stop any vitamin supplements that contain biotin a week before ALL BLOOD TESTS as biotin can falsely affect test results

Suggest you get vitamin D, folate, ferritin and B12 tested

Most important result is ALWAYS Ft3, followed by Ft4

TSH is frequently very low when adequately treated

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

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)

Is this how you do your tests?

Private tests are available as NHS currently rarely tests Ft3 or thyroid antibodies or all relevant vitamins

List of private testing options

thyroiduk.org/getting-a-dia...

Medichecks Thyroid plus antibodies and vitamins

medichecks.com/products/adv...

Thriva Thyroid plus antibodies and vitamins By DIY fingerpick test

thriva.co/tests/thyroid-test

Thriva also offer just vitamin testing

Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins by DIY fingerprick test

bluehorizonbloodtests.co.uk...

If you can get GP to test vitamins and antibodies then cheapest option for just TSH, FT4 and FT3

£29 (via NHS private service ) and 10% off down to £26.10 if go on thyroid uk for code

thyroiduk.org/getting-a-dia...

monitormyhealth.org.uk/

Also vitamin D available as separate test via MMH

Or alternative Vitamin D NHS postal kit

vitamindtest.org.uk

Blobby1234 profile image
Blobby1234• in reply toSlowDragon

I stop everything 24hrs before test since joining this thread! In fact I'm wondering if that's why test results are not quite the same as usual. Its quite hard telling your GP what to do. They don't take it kindly.

SlowDragon profile image
SlowDragonAdministrator• in reply toBlobby1234

Obviously just testing TSH is completely inadequate

Ft3 was ludicrously low

Was Ft4 tested ?

Blobby1234 profile image
Blobby1234• in reply toSlowDragon

Nope!

Blobby1234 profile image
Blobby1234

Just had the latest blood test. TSH 1.3 (0.2 - 4), T3 1.0 (0.9 - 2.5). Even crummier than before. I'm going to ask to be referred to an endocrinologist . I'm absolutely knackered, hair like string, feeling quite fed up, all of which will be attributed to lockdown.

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