Can someone talk to me about "fasting" blood tests please?

[sumsumsum]

I'm meant to go in and have a range of blood tests done. I need to be fasting, which the GP said is nothing except water for 12 hours beforehand. Thing is, I'm an insomniac and spend the night quelling anxious thoughts with tea and snacks : is the fasting essential, please? Is 12 hours negotiable? I can obvs avoid snacks but hot drinks are more difficult. Apologies in advance for being a wimp - insomnia is the very devil. If I'd had one cup of tea, and no more than that, would it completely skew the results?

[sumsumsum]

Ever heard of SEO, Sandy?

[SandyShoresMissingShoes]

Great link, thanks. I rely on MN to be have a bit more expertise than Google; usually MNers are generous in sharing sources they know to be reliable, as opposed to weird wikis.

Google and Google Scholar throw up pretty much everything from top quality research papers to articles like this. It's up to everyone to search first and read what shows up.

[PickleFish]

For some tests, they say clear liquids like tea or water with lemon are fine.

If it's the thought of the insomniac night that puts you off, could you fast in the day, and then have the tests in the afternoon? (you probably can't have them too late or they wouldn't get to the lab in time). But if you had your last tea at, say, 3am, then you could have an afternoon one, especially if you hadn't had food since the previous evening. Might feel harder as it's longer without food, but it's not during the night when you're stressed about being awake.

[sumsumsum]

Great link, thanks. I rely on MN to be have a bit more expertise than Google; usually MNers are generous in sharing sources they know to be reliable, as opposed to weird wikis.

Really useful to know fasting is unnecessary, as of two years ago.

[FancyNewBeesly]

My son has severe low sugars. If I tested him within an hour or two of eating or drinking anything containing glucose, you’d have no idea of the problem.

He’s 18 months old and just had a 15 hour fast in hospital. You can manage!

[SandyShoresMissingShoes]

Tip OP

Try google :)

Took me 30 seconds to find this with a few key words into the search engine.

www.statnews.com/2016/04/29/fasting-cholesterol-testing/

If I can do it.....

[sumsumsum]

Sandy, any chance of a link to that research, please?

[Chienrouge]

Yes I would ask if there was something I didn’t understand or wanted clarifying.
I’d ask the GP who had requested the tests.

[SandyShoresMissingShoes]

There was some new research not that long ago which said that for cholesterol tests, fasting didn't make much difference but the NHS is notoriously slow to make changes when new research comes out.

[sumsumsum]

They're thinking about statins because of their QOFs. I can't imagine anyone would lie about not fasting, fgs.

[TooManyWIPs]

They can now (within past 5 years or so I think) do an initial diabetes test without fasting as I think they check for a hormone marker rather than actual blood sugar reading, as I have this every 2 years due to being high risk for the condition due to already having other endochrine disorder. I used to have to do the fasting one.
Obviously if the non-fasting test brought up a result that was concerning I assume my gp would then send me for the fasting blood glucose test.
As others have said for the fasting one: only water allowed and if you have the appointment at 9/10am it's easily doable with last cuppa/snack at 7pm
Good luck!

[ShakeVigorously]

I did previously have blood tests for cholesterol and blood sugar done by a private GP without fasting.

So why was that?

Thanks for all your lovely empathy, those of you who work in the NHS. I don't just blindly obey - do you? Never ask questions when given an instruction? No?

I don't mind doing what I'm told if it's necessary. Dunno why a private GP would have a different opinion.

In that case you probably should have asked the actual GP who ordered the tests

[sumsumsum]

At last! An explanation! Thank, Giraffe. It's not actually common sense for the lay person, tis a tad more complicated than that, being science and all, and doctors having different views.

[negomi90]

Random blood sugar is not the same as a fasting blood sugar. A random blood sugar which is really really high can be helpful. A random blood sugar which is really really (hypoglycaemic low) can be helpful.
A middling random sugar is useless.

Likewise in terms of cholesterol - some bits can be done without fasting - HDL & total cholesterol. Other bits need fasting (LDL & tryglyceride).

The private tests you had would have provided some information, but not as accurate or as good as if you had fasted.

If they are thinking about statins, they are thinking about your cardiovascular risk profile. Knowing an accurate fasting blood sugar and the different forms of cholesterol are vital for this. So that you can be offered appropriate treatment.
Your health vs a hard night, the choice is yours.
But please be honest, if you don't fast then tell them when you have the test. Lying about fasting will result in your results being misinterpreted which will be dangerous.

[Sugarhunnyicedtea]

Some blood tests require you to fast. In this instance you are being tested for something that requires a fasting blood test. Unless the tests you had with the private gp were identical you can't compare them. If you can't or don't want to fast you need to speak to the doctor who requested the test

[JollyGiraffe]

Not necessarily Pippi

www.livestrong.com/article/484650-the-difference-between-nonfasting-fasting-cholesterol-tests/

[Pippioddstocking]

The private GP did your tests incorrectly .

[sumsumsum]

I did previously have blood tests for cholesterol and blood sugar done by a private GP without fasting.

So why was that?

Thanks for all your lovely empathy, those of you who work in the NHS. I don't just blindly obey - do you? Never ask questions when given an instruction? No?

I don't mind doing what I'm told if it's necessary. Dunno why a private GP would have a different opinion.

[Elusiveone]

I had a fasting blood test thursday and went from 7pm wednesday till 12.30pm thursday and only had water. You will be fine i got over the hunger side of it. Its important to stick to the rules as you would only have to redo it again if you didnt

[SandyShoresMissingShoes]

You are making a bit of a song and dance over this OP!

If you eat your last meal at 8pm and your drs appt is between 8-10 am next day you aren't going to starve to death.

To be honest, eating snacks all night long, or at all, is not doing your health any good.And tea surely keep syou awake longer as it's got caffeine in. If you are eating foods with fat and sugar in them overnight, it's not that surprising you may have high cholesterol. (Though it can be hereditary and not linked to diet or lifestyle.)

[Chienrouge]

Do you think they just tell you these things for fun? Why would they say ‘fast for 12 hours beforehand or it’ll skew the results’ if actually you didn’t have to fast for 12 hours beforehand and it wouldn’t skew the results? For shits and giggles?

[TenancyTroublesAgain]

You're having a range of tests done. Anything other than water will skew them.

" Nutrients in the foods you eat and beverages you drink can influence test results. For some tests, even the stimulation of digestion enzymes interferes with test results. The amount of time you need to fast can vary between eight and 12 hours. Glucose and cholesterol tests are examples of blood tests that require fasting."

[JollyGiraffe]

It seems common sense is really not that common.......

[Hypermice]

Hot water is fine, as long as you were told you could drink water, the temperature is irreverent

But no cheeky squeezes of lemon or anything in it. Honestly, anything else will skew the tests

[travailtotravel]

I have hot water...