Normal Ranges for T4, T3 & TSH

[d_oluwole]

Hi,

Please, what should be the normal ranges for the following thyroid tests:

T3

T4

FT4

TSH

Thanks

[Jaydee1507 Administrator]

This would depend on the lab and the equipment they are using. Ask whoever run the test to tell you.

[tattybogle]

There are no universal 'normal' readings for thyroid blood tests .. test ranges vary depending on the equipment used to do the test .

Different machines made by different manufacturers are calibrated differently , because the processes used to do the test are slightly different.

fT4 test ranges have a very wide variation , fT3 ranges are less varied, and TSH ranges are pretty much the same nowadays whoever makes it .

eg one manufacturer makes an fT4 test that has a (95% population reference) range of:

[7.9-14] .. another manufacturer makes an fT4 tests that has a (95% population ref) range of [12-22]

if you put the same blood sample through both tests .. you should get the same % through range , but the actual result (as a number) would be different , so you would get :

Machine A ......11 [7.8 - 14] about 50% through range

Machine B ......17 [12 - 22] also about 50% through range

Both result show the patient has an amount of fT4 that is in the middle of the levels found in 95% of the health population.

to get a '95% population range' , they test a certain amount of supposedly 'healthy' samples on the machine , they remove the highest 2.5% and the lowest 2.5% of results.. an dwhat they are left with is the 95% population range for that machine .

To interpret any thyroid blood result properly, TotalT4 / freeT4 , TotalT3 / freeT3,, you need to know the ref range used by the lab that did the test.

TSH is usually simpler.. most (UK) TSH ranges are roughly 0.4 - 4.5 ish .

( they do vary a bit , some are narrower eg [0.37 -3.6] , some are a bit wider with top end closer to 5 )

In reality is not a perfect system ... there are problems with the comparability between some tests :

healthunlocked.com/thyroidu.... freet4-testing-difference-in-reference-ranges-reading-matter-for-a-rainy-day-.

There are also significant issue's with the use of the word 'normal' :

helvella.blogspot.com/p/the... The normal range: it is not normal and it is not a range.