Help sought, AIT and carbimazole

[Fallman]

After 3 years on Amiodarone I was diagnosed with thyrotoxicosis. I was put on a combination of prednislone and carbimazole. Nothing much happened for 5 months with levels of T3 T4 very high and totally suppressed TSH. From that point onwards though my T3 T4 levels started to drop quickly until they became normal and my TSH followed and 4 weeks ago I tested normal in all three ranges. Yesterday though my bloods showed raised TSH levels and borderline low T3 T4. I am currently taking 10mg of carbimazole per day and am tapering prednisolone currently at 5mg. My question is, is the carbimazole now causing my TSH to rise to high and if so should I immediately stop taking it? Communication with my endocrinologist is very difficult.

Also, can anyone suggest a tapering schedule for prednisolone? I have been taking it since late Dec '23 max dose was 40mg/per day.

Thanks in advance

[PurpleNails Administrator]

welcome to forum

What are FT4 & FT3 results? Post them with with lab range.

Carbimazole needs to be adjusted by FT4 & FT3 Levels. & not usually prescribed unless it’s confirmed the hyper levels are expected to be a continuous issue. (Were TRab or TSI positive?)

Very likely you need to reduce if not stop carbimazole.

[Fallman in reply to PurpleNails]

Thanks for replying.Yesterday my TSH was 8.5muL and my T4 T3 were 13.4 and 3.9 pmol.

I've been diagnosed with AIT unknown type1/2. I think my Trab and Tsi were negative.

Lab ranges 0.27-4.2 normal tsh, 12-22 normal FT4, 3.1-6.8 normal FT3.

4 weeks ago those figures were 0.91 17.7 and 4.7.

(At their 'worst' in early January my levels were >0.05muL TSH 95.1pmol FT4 14.2pmol FT3).

I tapered from 50mg/pday carbimazole down to 10mg/pday and from 40mg/pday prednisolone to 5mg over the past 12 weeks or so.

I think you are correct and I should be stopping carbimazole with immediate effect at least until I can get some feedback from my endocrinologist, which unfortunately could be as long as 3 weeks.

I have another blood test booked for two weeks time, so that should provide more information in the meantime.

Any further input would appreciated.

[PurpleNails Administrator in reply to Fallman]

We do need lab ranges to interpret accurately as ranges vary between labs. By most ranges your are now at hypothyroid levels. Was TPO or TG antibodies tested? If Trab / TSI negative it’s expected hyper transient and levels will naturally drop.

Amiodarone-induced thyrotoxicosis (AIT) has two sub-types that need different treatments.

Type 1 AIT is caused by high iodine content of amiodarone, a main component of thyroid hormone, leading to excess production of thyroid hormone by the thyroid gland. This can worsen pre existing / or precipitate Graves or hyper toxic nodules.

Type 2 AIT is caused by inflammation of the thyroid gland from amiodarone, leading to release of excess amount of preformed and stored thyroid hormone from the thyroid gland. This can worsen pre existing / or precipitate Hashimoto’s (autoimmune thyroiditis) positive TPO / TG antibodies.

Type 1 AIT is treated with antithyroid drugs to stop / lower thyroid hormone production.

Type 2 AIT is treated with steroid to decrease inflammation.

Seems Dr has started both treatments. 10mg is low a carbimazole dose. Did you start on a higher dose? Levels were quite high so the drop has been great, how long have you taken carbimazole.

If endocrinologist isn’t getting back to you can you go to GP? a doctor should really be supporting your dose adjustments, with both carbimazole & prednisolone.

Are you in UK? Put country in profile, members often recommend private companies for blood testing for example but might not be relevant.