High T3 & been prescribed carbimazole.

[Charmollie]

I have been subclinical hyper for 2 or 3 years. I felt ‘ off ‘during February and March, predominantly plagued by heat sensitivity and itching and stomach pain/loose stools. My thyroid bloods were taken late April. TSH 0.01, FT3 14mu and my T4, 41.

I had repeat blood last week and although my T4 is down to 37.5 my T3 has shot up to 28. I saw a GP today who has prescribed carbimazole ahead of my endocrinology appointment. I am wondering what peoples experience of this drug are and how high the T3 can be before it is considered urgent?

[PurpleNails Administrator]

Welcome to forum.

How were you sub clinical previously (low TSH?) and your FT4 & FT3 have not been raised until now?

How much carbimazole were you prescribed? Your FT4 has not lowered a great deal but your FT3 have increased considerably (the range is much smaller)? Had you started carbimazole by this stage?

Disproportionately high FT3 isn’t unheard of but the sudden change with treatment is less common. It might just be the levels adjusting and will balance out if this becomes an issue you can ask to use block and replace regimen. Higher dose to block and replacement T4 (levothyroxine) to replace the levels.

Many people do well on carbimazole, I have been on moderate / low dose for over 3 years. A rare few can have reactions minor to severe. Make sure you read the patient leaflet carefully so you can be vigilant for any symptoms, especially the serious ones.

“how high the T3 can be before it is considered urgent?”

Any level above the range requires action. If it minor is might be transient and can be monitored. but if likely to be continuous it must be treated.

It’s not uncommon for levels with Graves (autoimmune causing continuous hyper) to reach 4x normal range.

If you are asking if there a certain level at which you may become seriously unwell there isn’t a specific number. doctors would be concerned if you showed signs of thyroid “storm”. Which can occur with trauma or medical crisis and uncontrolled hyper. This would have very obvious symptoms such as very fast heart rate, fever, sweating, shaking agitated or confused state & diarrhoea. All which would prompt an A & E visit.

You can help yourself by keep a diary of symptoms, medications & supplements & tracking levels & results carefully. It will also help you by making a note of following up when tests & appointments are due.

For full thyroid test you need:

TSH (thyroid stimulating hormone) this is a pituitary hormone which signals to thyroid to produce new hormone. Doctors often focus on this a conclude if this is in range so must actual levels but this is not always the case.

FT4 Thyroxine

FT3 Triiodothyronine, the more active thyroid hormone

TPO & TG antibodies (autoimmune conditions - Autoimmune thyroiditis & can also be present with Graves)

TSI or TRab must be tested to confirm Graves * was this done? Drs often assume all low TSH is Graves but you must ensure this have been checked. Being subclinical a number of years first is unusual. Graves often seemed to occur suddenly without warning.

Also important to test:

Folate

Ferritin

B12

Vitamin D

We are legally entitled to view our own blood test results, always obtain copies online or printed. (Never verbal or hand scribbled) as the lab reference range is needed (each lab range varies, so required for each result)

[Charmollie in reply to PurpleNails]

Hi and thank you for your detailed response. I have been prescribed 20mg x 2 per day. I am not sure I have graves although that diagnosis would make sense as I had 10months of steroids for PMR. My TSH and T4 have been a bit unstable for a few years. I can see my records and the T3 record is less.