TSH nhs and private same day test , different results

[Burgerballs]

morning all , just a quick question if any one of you lovely people could shed light on for me , I recently had a private test along with a nhs test TSH . Both did at the same time , the results came back with the nhs at 1.76 and the private at 2.12. Just curious 🤨 if anybody’s got any thoughts 👍

[tattybogle]

hi , there will always be slight differences between TSH tests done using different test methods ( even if both done from the same blood sample ) in fact even if you tested the same blood sample on the same test method in the same lab~ you often wouldn't get the exact same result twice .

a small difference is not unusual , it would be more surprising if you got the exact same result from both .

there are lots of problems with TSH / fT4 / fT3 testing methods/ standardisation ( or rather lack of it ), but the difference in your results is not large enough to be a problem .

TSH / FT4 /fT3 results are only ever a 'ball park' estimate/ snapshot in time~ never an absolute truth.

edit : eg these samples were taken just 45minutes apart on same day :

GP test (veinous blood draw) .................. 11am: TSH 2.65 [0.57-3.6] ........ fT4 15.7 [7.9-14]~128% through range.

NHS lab Exeter(MonitorMyHealth ~fingerprick) 11.45am: TSH 2.9 [0.27-4.2]...fT4 22.1 [12-22] ~101% through range.

the current situation is far from ideal :

healthunlocked.com/thyroidu... what-tsh-test-is-used-affects-diagnosis-of-hypothyroidism

healthunlocked.com/thyroidu.... /difference-in-reference-ranges-reading-matter-for-a-rainy-day-.

[Obsdian]

I have done tests two hours apart with similar differences.

[Lilian15]

I once had two blood tests taken and done at exactly the same time. One was requested by the consultant and the other by my GP. It was done at the same hospital, both NHS, yet not only were the numbers different, one showed I was overmedicated and the other showed undermedicated.

[sparkly in reply to Lilian15]

I've had that too. Gp and endo both requested the bloods. Same lab, likely tested on 2 different machines that wasn't calibrated the same. Ft3 and ft4 both different

[Lilian15 in reply to sparkly]

I can understand different calibrations, BUT they should both be showing high, or both showing low. If a person had only one test it meant they were treated right - or wrong depending on what machine the blood was tested on. That could mean hundreds of people were not being treated correctly. If they are going to go by blood tests you would think they would make sure the machines are calibrated properly.

[sparkly in reply to Lilian15]

Just looked back at my old post about itOne test ft3 5.0, ft4 4.80

Other test ft3 4.6, ft4 4.3

It was 10 years ago so hopefully things have improved