Starting dose

[reet-f]

What change in TSH can be expected after an initial 6 weeks on a starting dose of 25mcg levo?

[SlowDragon Administrator]

Standard starter dose of levothyroxine is 50mcg

You might see TSH go up further on such small starter dose

Bloods should be retested 6-8 weeks after each dose increase

Results from before starting on levothyroxine

THYROID STIMULATING HORMONE. *6.51 0.27 - 4.20

FREE THYROXINE 14.700 12.00 - 22.00

FREE T3 4.86 3.10 - 6.80

THYROGLOBULIN ANTIBODY 21.300 0.00 - 115.00

THYROID PEROXIDASE ANTIBODIES. 10.3 0.00 - 34.00

ACTIVE B12 61.900 37.50 - 188.00

FOLATE (SERUM) 6.07 3.89 - 26.80

25 OH VITAMIN D 55.9 50.00 - 200.00

CRP - HIGH SENSITIVITY 1.6 0.00 - 5.00

FERRITIN 55.4 13.00 - 150.00

Obviously vitamin levels need significant improvement

Presumably you are now taking vitamin D and daily vitamin B complex and separate B12 too

Looking at increasing iron rich foods in diet

Aiming for vitamin D at least around 80nmol and around 100nmol maybe better

Folate and ferritin at least half way through range

Active B12 over 70

Make sure you retest as early as possible in morning before eating or drinking anything other than water and last dose levothyroxine 24 hours before test

Only do private testing on Monday or Tuesday morning and post back via tracked postal service

Remember to stop taking any vitamin B complex or any supplements that contain biotin a week before ALL BLOOD TESTS as biotin supplements can falsely affect test results

Which brand of levothyroxine are you currently taking

[reet-f in reply to SlowDragon]

Thanks for your reply. I’m not taking levo (yet). My GP told me there was nothing wrong with my thyroid. He was suspended following a CQC inspection! I’m going to have a full thyroid test and take these to the new GP.

My question about the low starting dose was really to ask why it’s necessary for that first blood test after the initial 6 weeks on 25mcg as it is only a starting dose. What will the GP learn from the blood test that would inform his decision on increasing the dose?

[SlowDragon Administrator in reply to reet-f]

Levothyroxine doesn’t “top up “ failing thyroid. It replaces it

if you think of it this way

our thyroid controls our metabolism

As an example....if, when perfectly healthy, your own thyroid made the equivalent of 125mcg levothyroxine....and this metabolism is controlled by pituitary sending messages - TSH (Thyroid stimulating hormone)

Then as your thyroid starts to fail (usually due to autoimmune thyroid disease) ....you might get diagnosed when your thyroid has reduced output to roughly equivalent of 75mcg levothyroxine

Pituitary has noticed there’s a drop in thyroid hormones in the blood....(that’s Ft4 and, most importantly, the active hormone Ft3) ....so to try to make more thyroid hormone ...pituitary sends out stronger message to thyroid - TSH rises up

When GP starts you on 50mcg ....initially you feel a bit better ....as you have 75mcg from your own thyroid and 50mcg levothyroxine

But (here’s the bit many GP’s don’t understand....) ....levothyroxine doesn’t “top up” your own thyroid output.....well it does very briefly....but the pituitary very soon “sees” the levothyroxine in the blood....and TSH starts to drop

So at the end of week 6 ....TSH has dropped a lot. Your thyroid takes a rest ....has a holiday

So at this point you are now only mainly using the 50mcg levothyroxine....which is actually a dose reduction down from managing on 75mcg from your own thyroid before you started on levothyroxine

So you start to feel worse .....and are ready for next 25mcg dose increase in levothyroxine

Modern thinking ....and New NICE guidelines suggests it might actually be better to start on higher dose

....but many medics just don’t read guidelines

....and very many patients can’t tolerate starting on more than 50mcg and need to increase slowly upwards in 25mcg steps

[SlowDragon Administrator]

guidelines on dose levothyroxine by weight to help push for further increases over coming months

Even if we frequently 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 eventually 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...

[reet-f in reply to SlowDragon]

Thank you SlowDragon. Thanks for all this information. I will approach the new GP with it and finally get the treatment I need.