Blood Tests - What does this mean?

[nowwaitaminute]

Hi, I was diagnosed with hypothyroidism 10 years ago. I recently had a blood test to check my thyroid levels as I’ve been getting tired again. I haven’t received the results, but I have received a message saying that I’ve been booked in for a full blood count. Why is this and what does it mean?

Is it related to my thyroid at all? They also took my blood pressure and height & weight.

Thank you.

[PurpleNails Administrator]

Full blood count (FBC) won’t include thyroid function (TSH, FT4 & FT3) sometimes it’s requested as TFT (thyroid function test) the lab will test TSH and will only test FT4 if TSH abnormal.

[nowwaitaminute in reply to PurpleNails]

Thank you for the reply! 😊 So the FBC isn’t requested because of my thyroid, they are just doing a FBC for another reason (is that right? 🥴)

[helvella Administrator in reply to nowwaitaminute]

You cannot tell why they requested FBC from the fact that they have requested it!

But it is often done as a general "check everything else is OK" - at least, everything the FBC includes. It often gives hints of other issues - if there are any. For example, elevated MCV suggests but does not prove low B12. Low MCV suggests but does not prove iron deficiency. Elevated RDW suggests the possibility of being both low in B12 and low in iron - but does not prove them.

All these need more work to fully investigate. But if the FBC comes back with no question marks, that is a very good start.

It is cheap and measures a considerable number of features.

[nowwaitaminute in reply to helvella]

Thank you for explaining. I think if anything I’m just over thinking it tbh 😅 Hopefully everything’s okay 🤞🏻

[PurpleNails Administrator in reply to nowwaitaminute]

I have a GP who always requests FBC along side thyroid function. another GP always add liver function. (I’m treated for hyper) FBC screens for quite a few potential issues. As long as Thyroid is requested too & not instead I think the GP is just adding the usual standard test for good measure.

Lab test online good site for info on tests

FBC “Commonly requested as part of a general screen in a patient who is unwell to screen for a variety of disorders, such as anaemia and infection, inflammation nutritional status and bleeding”

labtestsonline.org.uk/tests...