hypothyroid

[loopyloo49]

I have been hypothyroid for about 20 years and been stable on 125mcg of levothyroxine. I recently had my yearly check and my TSH was 0.02, FT4 16.8 range (11 - 23) and FT3 4.2 (3.9 - 6.8). My doctor reduced my levothyroxine to 100mcg and re tested a month later but during the month I had lots of hypothyroid symptoms coming back - extreme sensitivity to cold, pins and needles in hands and arms, extremely tired, very heavy period, dry skin and hair, daily headaches and migraines and feeling dizzy when standing in a queue. I also had several hypoglycaemia type attacks which I haven't had in years (non diabetic). My test results after the month were TSH 0.04, FT4 15 and FT3 4.1. My TSH has only once before become suppressed but FT4 was 24.7. I am on low dose HRT and take Amitriptyline for Migraine but no other medications or supplements. Along with the TFT my doctor did lots of other blood tests and also tested Vit D and fasting blood glucose which were all normal.

I just wondered if any of the experts could give an idea what would cause my TSH to become suppressed without the corresponding rise in FT4 and why my hypothyroid symptoms would come back if I'm overmedicated?

Thank you in advance for your help.

[Dr Masud Haq]

Thank you for your post.

There could be a number of reasons that your TSH has now become suppressed.

1. Previous prescription of TEVA brand of thyroxine. This was withdrawn over 12 months ago as it was considered to be less efficacious then comparable brands. As a consequence, patients were needing more thyroxine than they actually needed

2. Possible drug interaction which is affecting bioavailability or clearance of thyroxine

3. Steroid use

With regards to why you might be getting hypothyroid type symptoms. It's possible that the symptoms may be due to another condition unrelated to your thyroid e.g., anaemia, liver or renal disease, disturbed sleep, high levels of stress. Alternatively, you may have become accustomed to running lower levels of TSH. The new lower dose of thyroxine, may have affected your underlying metabolism which could be manifesting with your current symptoms.

Regards