I just compared lab results from this year and last year to previous years (going back to 2010 when I started using this particular lab).
I have noticed two changes in the past ten years:
the reference ranges for TSH have gone from 0.35-4.9 to 0.35-4.5 mUI/L...which I believe is good)
ref for FT4 unchanged (0.7-1.5 ng/mL)
the reference ranges for FT3 have gone from 1.7-3.7 pg/mL to 1.7-3.2 pg/mL...which is not so good for me as I feel best with FT3 levels around 3.5-3.6 which now would mean I am overmedicated whereas before they were in range. The best I´ve felt ever was with FT4 1.2, FT3 3.6 (then in range, now slightly out of range according to new ref ranges). That was on T4 + T3, dosing by symptom-relief only, but it´s pretty interesting that I had mid-range FT4 and top of range FT3 (suppressed TSH but I never cared about that)...something I would never, ever be able to achieve on levo only...and I´ve never felt better. So, a lab changing ref ranges, and a doctor obsessed with said ref ranges could mean huge potential problems.
Is there a reason why a lab would change its reference ranges for the TSH and FT3, but not the FT4...? Are there any international or European recommendations to lower narrow down FT3 reference ranges?
I know ref ranges vary from lab to lab, but does this mean it´s time to find a new lab as I find their current ref ranges for FT3 too narrow...?!