Reflex free T4? What is it?

[rjerome812]

Hello, I have had a T3 and T4 test in the past, but the new doctor put for my next Labs, TSH with Reflex Free t4. I have never seen it worded like that and what does it mean?

[jimh111]

I had never heard of this. After a bit of research I found it means they will assay your TSH only and if this is outside its reference interval they will then automatically do an fT4 assay. This is OK if you have had TSH, fT3 and fT4 checked before and the fT3 and fT4 look consistent with the TSH and TSH reflects how you feel. Otherwise they should check all three but in general they don't have the gumption to understand that all three are needed. So, in a nutshell, they are just checking your TSH.

[helvella Administrator Thyroid UK]

It is also sometimes referred to as a cascade.

Fundamentally it means one thing - saving the cost of tests which are assumed to be unnecessary on the most unscientific basis.

If TSH is in range don't test anything else. If it isn't, do a Free T4 test. (It should carry on with at least Free T3 - but most times that isn't even an outside possibility.)

There is no certainty that an in-range TSH means that Free T4 is acceptable.

I have several times suggested getting a collection of genuine lab results where TSH, FT4 and FT3 were all performed. Then blank out one result from each set. Finally, get several endocrinologists, GPs and anyone else to review them and fill in the blanks. If it is unnecessary to do all three tests, then the endos should get 100% right. I don't see there being any chance of that.

[rjerome812 in reply to helvella]

Does this mean if my Tsh is in the normal range they will not test anything else? I have had normal TSH and T3 and T4 in about a year ago, but I had high TPO antibodies.

[helvella Administrator Thyroid UK in reply to rjerome812]

Yes - that is exactly what it means.

If you read around some medical papers you will see laboratories and doctors highlighting the huge number of thyroid tests being done these days. In order to reduce the cost of these tests, they put up this idea of using TSH as a screen - if TSH is OK then FT4 and FT3 must be OK because TSH is exquisitely sensitive. Please try to ignore that this is not based on science or sense. Even if they did FT4 and FT3 simply being in range would often be regarded as OK.

May I suggest that if companies like Mercury Pharma are gouging the NHS with the price of liothyronine, perhaps they should be questioning what the suppliers of analytical products are charging? Without knowing anything about the costs, it seems to me that reducing what you pay is a better approach than reducing the number of tests.

Antibody testing is controversial with the traditional view being that once positive, there no point in further tests in future.

[Kathy21 in reply to rjerome812]

In our area,Leistershire, if TSH is in range the lab will not test ft3 or ft 4 even if the go has written a request on the form. I haven't had mine done now for about 4yrs.

[rjerome812]

I guess the sad part is no matter what i feel or family history or ultrasound, I cant feel better if doctors just go by certain tests . Im getting to the point that i should just stop pushing. apparently I have to feel alot worse and gain another 30 lbs before and one takes me seriously. My mothers side are all hypo. But until my TSH is out of range well then Im good. In the mean time they wan to send me to every specialist under the sun (money, Money) , because it must be something else in their eyes. Sorry frustrated and just ready to give up .

[humanbean in reply to rjerome812]

In several countries around the world it is possible to get private blood tests done without the intervention of a doctor. For example, in the UK getting a finger-prick test done for TSH, Free T4 and Free T3 costs £39. (I don't know if you are in the UK.)

medichecks.com/thyroid-func...

Ah - just checked and I see you are in the US. For testing without involving a doctor in the US, see this link - you have a choice of several labs :

stopthethyroidmadness.com/r...