Thyroid UK
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Hi all it is my first post on here and I wanted to say I am glad I am not alone. I do not understand all these blood tests as I had a breakdown in December but over it now do not know why it happened. I was called into my GP two years ago who told me my yellow serum was low, I asked what that meant and she responded by turning her computer screen round saying you T3 is almost out of the box. She gave me leva thyroxine to take 50mg told me I had to take it the rest of mt life. Well that was all nothing else was explained to me. My usual GP was away so I could not see him I was lost. I lost my mum whom I cared for in the December lost 3stone but I also had the test around hat time so I thought it was because of that. I feel so unwell all the time. Please can you help me just by listing what not having enough yellow serum means in English. All the simptoms of this hen I can wipe out by treating what is not caused by it. Please help me I have had the blood test 4 times now and there is no change.

4 Replies

Never ever heard of that in relation ot thyroid (just liver disease. Ask the surgery for your blood test results and post them here so people can comment (either type them or start a new thread with an image). It's very rare for the NHS to test T3 unless your are overactive - are you sure that's what she said? The blood tube might have a yellow top, but that's just deliberately being obscure and making her comments impossible to understand.

BTW it your right under the Data Protection Act and NHS Constitution to have access to all your test results, so don't take no for an answer - you can just ask them if you can see the screen and write them down if they try to charge you for a print out.


I am unaware what 'yellow serum' means. You stated in your previous post that you were hypothyroid and only on 50mcg of levothyroxine. Has that dose been increased since your last post as it is a very small dose if it has not been increased. That, in itself, may have made you feel unwell.

This is a link and you will see that 'yellow serum' is to do with the containers that deal with different blood tests.

I would ask for a complete new blood test for your thyroid hormones, i.e. TSH, T4, T3, Free T4, Free T3 and thyroid antibodies. Get the earliest possible appointment and fast (you can drink water) and allow 24 hours between your last dose of levo and the test.

Get a print-out of the results with the ranges and post on a new question.

If you've not had recent tests for B12, Vit D, iron, ferritin and folate ask for these to be done at the same time.


I was at first on 100 mg but I became very ill had to be rushed into hospital as my blood pressure was kicking of over 200 and they thought I had a a heart attach. All bloods were taken in majors wired up everywhere, I told them it was just a very bad headache but no one believed me and I had to stay in for 3 days. Each time I saw a dictor or nurse I showed them my 100mg but no one believed that was was I amens ill. So I said I would only take 50mg from noe on but I feel so ill every day. I feel like I am being attacked by my own body


Hope things improve for you

Don't know what else to say xxx


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