Thyroid UK
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blood test for thyroid

would I need to go for thyroid test with fasting,, would it make any difference if I fas and fast not before the blood test..

Also please let me know what is meant by blood turning lise when you submit blood sample for thyroid test alongwith fasting.. this happened to me when I gave my blood sample for testing three times this week. Everytime they are answering me this only . Please help me anyone what should I conclude out of this,, I'm in a great fix.

4 Replies

Welcome to our forum leelaran868.

I am not quite sure what you mean by

"blood turning lise when you submit blood sample for thyroid test along with fasting"

You must be feeling unwell when you've had three blood tests this week so they might be trying to find out what is wrong with you.

It is now advised (just recently) that we should fast before a thyroid gland blood test, it should be as early as possible in the morning. If you have been taking levothyroxine medication you should leave about 24 hours approx between medication and dose. Normally, we have a higher cholesterol too as our metabolism is too low and cholesterol gathers but it does reduce without statins and when you are on levothyroxine.

Always ask for a print-out or copy of your blood test results, for your own records, and so that you can post them here if you have a query and our members will answer If your doctor hasn't tested your Vitamin B12, Vit D, iron, ferritin and folate ask for these too.



Actually for the past two years I'd been on thyroxine 100 mg. Now I was using 75 mg for about one year under doctors instruction only whe I had tsh around 6. now that I'm noticing hair thinning I ws going to check my tsh level.

But I ended up like this.. "blood turning lise".. which is not understandable to me


I don't understand the phrase either but if you can get a print-out or copy of your latest blood test results and post on a new question, members will respond.

Doctors shouldn't reduce levothyroxine due only to the TSH blood test it can make us have more symptoms.

I suggest your get new blood tests as indicated above and start from scratch. I don't think your doctor knows too much above treating hypothyroidism.

Your TSH at 6 was too high so he shouldn't have reduced your dose of 100mcg to 75mcg.

Once we have your results, with the ranges, members will comment.


This is a guess. Blood can be affected by haemolysis.

Hemolysis, also spelled haemolysis (from the Greek αἷμα (aima, haema, hemo-) meaning "blood" and λύσις (lusis, lysis, -lysis) meaning a "losing", "setting free" or "releasing"[1]), is the rupturing of erythrocytes (red blood cells) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo or in vitro (inside or outside the body).

If this occurs to the blood sample, then they might not be able to test it. It is fairly common. The Wiki article should give you some ideas about why it happens.


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