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Why does blood tests need to be fasting?

A

andyrobo

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This may be a completely daft question, but why does my 6 monthly blood tests need to be a fsting test? How would having my breakfast affect the results? No one has ever explained that to me and we just take it for granted, but I am nosey and like to know the scientific bit!

Thanks to anyone who knows!

Andrea
 
I've never been told to fast before a blood test , I have mine done at the hospital now.
Maybe they ask because they want to find out how your body tests before eating?
 
The Hba1c test does not require fasting but the Cholesterol and certain other tests do.

Any intake of foods, fats, such as milk, will muck up the results of the Cholesterol test. To get the most valuable, accurate information from your blood test, don't sneak even a mint.

As these tests are often taken together then that is why you have to fast.
 
andyrobo said:
This may be a completely daft question, but why does my 6 monthly blood tests need to be a fsting test? How would having my breakfast affect the results? No one has ever explained that to me and we just take it for granted, but I am nosey and like to know the scientific bit!

Thanks to anyone who knows!

Andrea
Click to expand...

I think thats a good question Andrea and something I had been wondering too!
I mean, its not as if we all go around starving ourselves, is it, so shouldnt tests reflect the normal state we are in, i.e. with something in our tums?!!
Sometimes I wonder if these things are done simply because "its the way we have always done it" :!:
 
I thought it was so that they cpuld get a base line result that is unaffected by the intake of food. We all know what happens when we eat certain foods, our levels go up depending on what food it was. After a 12 hour fast the effects of most foods should be at there minimum and give the doctors a base line to work to.

But I could be wrong!

Brian
 
I think it depends which doctor writes out the form for your bloods. HbA1c doesn't need to be fasted but sometimes they make me do it anyway. Never been told to fast before a lipids test. Sometimes I'm told to fast for the plasma glucose and sometimes not. Doctors are fickle :-)
Just make sure they give you a morning appointment if they want you to fast!
 
I recently attended a Diabetes education course at the hospital and we were informed that there is now no need for a fasting test for lipids or HbA1c.
 
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