hollygrace99 The advice always given on the forum for testing thyroid, when TSH is important to be high in order to avoid a reduction in dose of Levo or when looking for an increase is:
1) Book the earliest appointment of the morning. TSH is highest early morning and lowers during the day.
2) Fast overnight (water allowed). Eating lowers TSH.
Also, when the free T results are important:
3) Leave off Levo for 24 hours - take it too close to blood draw and you'll get a result reflecting that you've recently taken it due to when it peaks in the blood. ncbi.nlm.nih.gov/pubmed/836... -
"...... Time-course analysis showed that free and total thyroxine levels remained significantly elevated above baseline for 9 and 5 h, respectively, after a levothyroxine dose. In conclusion, there is a transient increase in thyroid hormone levels for 9 h after an oral levothyroxine dose. Accurate assessment of thyroid hormone levels in patients receiving levothyroxine therapy should take this into account. ....."
4) Any T3 meds - T3 or NDT (because it contains T3) - leave off for 12 hours. Again, taking it close to blood draw shows you've recently taken it and will give a high result. Leaving it more than 12 hours will give an artificially low result. When taking T3 in any form it's the FT3 result that is most important so if taking NDT it should be left off for 12 hours not 24.