TSH test

[Print1972]

Hi. I think I may have gone about my last blood test incorrectly, especially after reading information on here. My last test gave a TSH of 0.8. However, I had the test taken mid afternoon, 2 hours after my second 1½ grains of Thiroyd NDT. I always take the 1st 1½ grains in the morning. Is it possible having the blood test when I did, could give a false reading?

[SeasideSusie Remembering]

The TSH test is pretty irrelevant when taking thyroid hormone, and particularly when taking NDT as TSH will be low or even suppressed. When taking NDT it is FT3 that is important.

Patient to patient advice here is always have blood drawn at the earliest appointment of the day after an overnight fast as this gives the highest possible TSH, TSH is highest early in the morning and lowers throughout the day, it also lowers after eating. Also, NDT (and T3) should be left off for 12 hours (Levo 24 hours), if blood draw is too close to taking thyroid meds you are basically reflecting the dose just taken.

[Print1972 in reply to SeasideSusie]

Hi. Thanks for the advice. I've pretty much done the opposite of what you've advised. I'll ask my GP to put me in for a freeT3 test. What range should I be looking at for free T3?

[SeasideSusie Remembering in reply to Print1972]

Is your NDT prescribed or if self sourced does your GP know you are taking it?

Your GP may request FT3 but the lab decides if they're going to do it. The lab my surgery uses will do my FT3 if TSH is suppressed, and as my TSH is always suppressed the FT3 gets done.

If you can't get it done on the NHS then there is always a home fingerprick test with Medichecks or Blue Horizon. If all you want is the basic thyroid test then Medichecks often has it on offer on Thursdays - Thyroid Monitoring (TSH/FT4/FT3). Normal price is £39 but often discounted to £29, same price as FT3 alone and better to get them all done at the same time.