TSH Reflex

[Hamster18]

I just asked my GP if I could have a blood test for TSH, T4 and T3 and he said it's the TSH Reflex I have to do. I'm confused!

[helvella Administrator Thyroid UK]

TSH Reflex is their way of saying:

TSH only - but, if TSH is very high or very low, do Free T4, and if TSH and Free T4 are very odd, maybe do Free T3.

That is, extremely likely to be TSH only.

It is a way of reducing the numbers of Free T4 and Free T3 tests done. They base it on the assumption that if your TSH is inside the reference interval, or quite possibly, outside but not too far, they'll save some money by not doing any further testing.

(There is an argument, which could occasionally be good, that if your TSH is way out, they will automatically do Free T4, even if the doctor didn't ask for it. But seems set up mainly for cost reasons.)

[jimh111]

I would submit a freedom of information request to the hospital asking how much the fT3 and fT4 assays are and for a copy of the notice stating that GPs may only do TSH reflex.

I found that it costs my local hospital 92p for fT3 and fT4 assays.

They do this to save cost but it costs a fortune in additional healthcare. They also do it to avoid effort, they don't like work, so submit a freedom of information request and give them some work.