Arrhythmia

[CarnelianT]

Hi. I am usually on 100 mcg of levothyroxine daily. A few weeks ago I started experiencing erratic heart rate. I am aware of arrhythmia associated with levothyroxine and dropped my dose to 75 mcg just to see if that made any difference. It hasn't. I had a thyroidectomy nearly 3 years ago for cancer and have been on the 100 dose to prevent recurrence. Any advice would be welcome.

[SlowDragon Administrator]

Irregular heart beat can be due to being under medicated

Or different brand levothyroxine

Do you always get same brand of levothyroxine

Which brand

What vitamin supplements are you currently taking

When were vitamin D, folate, ferritin and B12 last tested

Please add most recent results and ranges

Bloods should be retested 6-8 weeks after any dose change or brand change in levothyroxine

For full Thyroid evaluation you need TSH, FT4 and FT3 tested. Also EXTREMELY important to test vitamin D, folate, ferritin and B12 at least annually

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/

NHS easy postal kit vitamin D test £29 via

vitamindtest.org.uk

[SlowDragon Administrator]

guidelines on dose levothyroxine by weight

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...