Questionable validity of test results?

[Fifteen]

Do thyroid tests have any use or even any validity? My results from the same blood draw but analysed by different laboratories have varied once again.

My story:

29/07/21 GP's NHS results:

TSH >0.01 (0.3 - 4.2)

FT3 4.4 (2.6-6.0)

FT4 14.2 (9.0 - 23.0)

29/07/21 Blue Horizon results:

TSH >0.005 (0.27 - 4.20) mU/L (New range and unit)

FT3 4.85 (3.1 - 6.8)

FT4 21.3 (12 - 22 pmolL)

When asked about the differing results, the response included:

You were is a hyperthyroid state at time of tests

Reported FT4 level is unreliable if you are taking T3

Whilst a lower TSH is the goal if one is taking T3, a very low level may imply overmedication regardless of FT3/FT4 levels

To continue: GP's NHS 21/01/22

TSH >0.01 (0.3 - 4.2)

FT3 4.8 (2.4 - 6.0)

FT4 15.7 (9.0 - 23.0)

T3 medication change by Endo from 15mcg to 20mcg T3, taken morning and early afternoon. Continuing 125 mcg T4 (I had recently decided to take 125mcg daily instead of 100/125mcg alternate days).

Latest - variation most confusing of all as officially both NHS testing

GP's NHS 11/04/22

TSH >0.01 (03 - 4-2)

FT3 5.4 (2.4 - 6.0)

FT4 14.3 (9.0 - 23.0)

Monitor Health - NHS Private 11/04/22

TSH > 0.01 (0.27 - 4.2)

FT3 6.3 (3.1 - 6.8)

FT4 21.8 (12.0 - 22.0)

With these variations in FT4 results from the same blood draw, do these results have any validity?

[tattybogle]

This post discusses the issue in depth . healthunlocked.com/thyroidu...

Especially with fT4 results done on different platforms ...i'm in the 'dubious' camp.

If you want to compare your fT4 this time to last time , then knowing what i know now , i'd use the same lab each time .

it' not so much a problem of any one lab being any more 'accurate' than the other , but the comparability between test platforms using different testing methods / with different ranges .. does seem to be a problem that is 'far from sorted' .

[thyr01d]

I think they do have validity because the ranges are different but looking at where you are in the ranges, say as a percentage, the results are pretty similar.

[tattybogle in reply to thyr01d]

it' s the fT4 's that are the problem.

29/07/21 GP's NHS results:

FT4 14.2 (9.0 - 23.0) 37%

29/07/21 Blue Horizon results:

FT4 21.3 (12 - 22 ) 93%

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

GP's NHS 11/04/22

FT4 14.3 (9.0 - 23.0) 38%

Monitor Health - NHS Private 11/04/22

FT4 21.8 (12.0 - 22.0) 98%

[Fifteen in reply to thyr01d]

Well spotted. Thank you. Just now have to decide whether to ask endo tomorrow for an increase in levothyroxine

[Fifteen in reply to thyr01d]

Well spotted. Thank you.

[Fifteen in reply to thyr01d]

Now to decide whether t ask the endo tomorrow for an increase in levothyroxine based on the NHS result