Thyroxine brand change North Star to Mer ury Pharma

[Fredthedog]

Hi,

I've just received my latest prescription for thyroxine and usually have North Star tablets. I've received Mercury Pharma ones this time. I think I read on herethst we shouldn't change brands? Can I take these or do I need to ring the pharmacy to get these changed? I don't have any of my old ones left for today either 😬

[helvella Administrator Thyroid UK]

There are two main problems changing brands.

First, you might find one make less tolerable than another.

Second, slight differences in absorption mean that a dose adjustment could be required.

25 microgram Northstar tablets are actually Teva product.

50 and 100 microgram Northstar tablets are actually Accord product.

You might as well try them and see how you get on.

[Fredthedog in reply to helvella]

Thank you for this. I rang the pharmacy and apparently there are big supply issues with North Star so I will see how I get on! I've just started feeling better since a thyroid lobectomy and Hashimoto's diagnosis in October so am just wary about anything that might set my anxiety off again!

[SlowDragon Administrator]

Have you had levothyroxine dose increased to 75mcg yet?

You may find you prefer Mercury Pharma brand. Available in 25mcg, 50mcg and 100mcg tablets.

Are you working on improving low vitamin levels, especially low ferritin

[Fredthedog in reply to SlowDragon]

Hi Slowdragon 😊

Consultant wouldn't agree to dose increase but has agreed to retest bloods in May so I will advance book an 8am appointment to get best result.

I've been taking ferrous sulphate, B vitamin complex, vitamin D and k2 and magnesium and I am feeling a lot better so hope it is all starting to work. I am still freezing cold with occasional muscle cramps and dry skin but I feel things are slightly improved. Anxiety generally much better apart from pms so I think I am generally quite hormone sensitive.

[SlowDragon Administrator in reply to Fredthedog]

Presumably endocrinologist is diabetes specialist

Ask them at next consultation why they aren’t following guidelines

guidelines on dose levothyroxine by weight

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...

[Fredthedog in reply to SlowDragon]

It is an endocrine surgeon I am under rather than endocrinologist, so I am not sure how much of the hormone side they are specialists in. If I am 55kg would you think that 75mg would be about right?

When I asked about a dose increase they said the aim is for TSH to be under 2 and to be wary of overmedication as this can cause nasty side effects - I had mentioned night time palpitations and they said increased dose could make these worse.

I am going to try to push this at my next appointment but I'm sure they think all of my symptoms are psychosomatic due to my anxiety.

[SlowDragon Administrator in reply to Fredthedog]

55 x 1.6 = 88mcg as the likely dose you might need per day

EVENTUALLY. But we have to increase slowly upwards

88mcg x 7 = 616 total per week

Perhaps 600mcg total .....or might be 625mcg per week

75mcg x 4 days a week and 100mcg 3 days week = 600mcg

Important to get vitamins at optimal levels

[Fredthedog in reply to SlowDragon]

Thank you again for your helpful suggestions 🙂

[Ellie-Louise in reply to SlowDragon]

I’m on 75mcg., I am and feel, perfectly fine but going by your calculations I should be on 113mcg.

So I can’t believe one fit suits all. 😮

[SlowDragon Administrator in reply to Ellie-Louise]

If you feel fine....then that’s perfect

If you felt under medicated and full thyroid testing confirmed that, then the guidelines can be helpful to push for dose increase in levothyroxine

Obviously some people may be fine with less that guidelines

Some people need considerably higher doses than guidelines, especially if lactose intolerant