Relaxing TSH suppression: When is this usually done?

I was diagnosed with PTC in November 2020 (25M) after a biopsy taken when I found a lump in my neck.

December 2020: TT

January 2021: Histology comes back, PTC with 30% tall cell features (potentially more aggressive than the normal variant), extrathyroidal extension into strap muscles in neck, microscopic positive margins, 2 central lymph nodes also found to contain cancer. Thyroglobulin 3.0.

February 2021: RAI 3.7GBQ. Thyroglobulin was 2.2 the day before RAI (24 hours after one thyrogen injection) and climbed to 4.7 immediately before RAI (two Thyrogen injections to stimulate the TSH). Post RAI uptake scan looked good, there was uptake in the neck which looked like residual thyroid tissue rather than disease. No uptake in any lymph nodes or any suggestion of distant mets.

June 2021: Unstimulated Tg 0.9

November 2021: Unstimulated Tg 0.6 and neck ultrasound shows no evidence of disease recurrence. At this point the endo mentioned that suppression would be needed for at least two further years.

May 2022: Unstimulated Tg < 0.2 (Undetectable?)

My limited knowledge of Tg is that my very low Tg suggests that my treatment has worked well and indeed my endo said back in November that my 0.6 result suggested I have responded beautifully. I think my slightly scary histology features means that they wanted to be a bit more aggressive in the suppression at least in the mean term, but atm I’m on 200mcg of levo 4 days a week and 175mcg the other 3 days. TSH is 0.02.

I’m slightly concerned about the long term effects of TSH suppression, albeit I’d rather live with that if there’s a potential recurrence that needs to be suppressed. I’d be interested to hear the forum’s thoughts on maybe going down to 175mcg every day and hoping that the TSH stays below 0.1, albeit higher than the 0.02 level we are at now? And then maybe scaling it back even further if things are still looking good in 18 months? 

  • Guidelines may have changed, but my surgeon and oncologist were happy to let me relax my TSH suppression at around the 5 year mark. Since then, I aim for around  0.1 to 0.3 I also had one of the potentially more difficult variants, but I was never able to get my FT4 even close to being in the right range, and so they realised there was no point continuing to suppress the TSH if it might lead to longer term stress on my heart.

    My guess would be that if you continue to get good Tg results, they'll relax your target TSH at the 5 year mark.

    Any changes to your dose need to be agreed with your medical team. 

    You don't mention what your Ft4 is. I would expect that to be a key factor in what the docs advise you to do.

    Best wishes


    “Scars are tattoos with better stories.” – Anonymous

  • FT4 is in the 16-17 range, I’ve been pretty lucky to be able to keep my TSH suppressed without going hyper (at one point it was 28, but we cut my levo down from 200 per day and my FT4 came way down and TSH barely rose at all)