Had follow up blood tests recently after levothyroxine increase from 25 micrograms to 50 micrograms. Did tests through both the GP and Medichecks (since they had the Thyroid function test on offer a few weeks back). I have a professional blood draw at a local clinic for the Medichecks test, rather than finger prick at home, to ensure the best outcome.
I follow the suggested blood test protocol on here: morning test, last LT4 tablet 24 hours before... the only caveat being, this time I could only get a late morning GP booking so I had to have my appointment at 11:25 and I had a running client that morning so I really had to have a cup of tea and an energy bar before going to the GP, otherwise I would have keeled over - so the time difference since my last tablet for the GP was about 27 hours and I had had a tiny amount of food beforehand (the protocol for the Medichecks blood draw was 100% correct).
The GP did request a FT3 analysis and annotated that I was querying that I might be a poor T4 to T3 converter (based on previous Medichecks results - and further supported by the latest Medichecks results). The GP's phlebotomist confirmed that there was a TSH/FT4 request AND a separate FT3 request... she did three sequential blood draws, which I was not expecting, as the GP had also requested a full iron panel - that I had requested previously, but was refused at that time - AND a B12/folate test - that I think was accidentally carried over from the B12 test I recently got separately because it was missed in the previous bank of tests.
ANYWAY... what happened was, rather than doing TSH/FT4 and FT3 analyses, the lab did TSH/FT4... and TSH/FT4 again!!! So the same blood draw by the same phlebotomist, at exactly the same time, under identical conditions. 🙄
Now... take a look at the two sets of data in the yellow highlighted boxes in my results spreadsheet. These show the two sets of reported results from the same blood draw. The TSH readings vary by 0.1 (which equates to ~2% variation) and are both still high through the range... BUT the FT4 readings vary by ALMOST 100% (actually ~93%). I find this absolutely crazy! I cannot comprehend how such different readings can be generated from two blood samples taken at exactly the same time. The FT4 values put me either 31% through the range - so needing a dose increase (on paper) OR 114% through the range, i.e. OVER range - so needing a dose decrease (on paper).
This is RIDICULOUS!
[Incidentally, I *feel* like I need a dose increase... remains to be seen what the GP says 😉]