Fasting labs?.....what else don't I know?

glucose and cholesterol levels need to be done fasting.  All others are fine with food.  As fine as supplements go, according to 2 different NUTs that I go to, they say that I need to stop my vitamin D for 1 week (I take it 2 times per week), my B12 injections for 1 week (take 3 times per week) and all other supplements for 3 days.  When I asked why, she said that you get a false elevation of your levels by taking them immediately before your labs.  I am RNY, so I don't take my D as often as you do.  For daily vitamins, she says 3 days.  Her explaination is that if you are taking a large dose a couple of times a week and you take the dose right before your blood work - it goes into your system but doesn't have time to work itself through your system and it shows up in your blood as what you just either injected or injested and not what your actual level is.  By waiting  some time for it to work its way through your system, you are getting a better reading of what is actually in your system.

When I asked vitalady about this, she said she does this too - she waits I believe 1 week after b12 injections to get her blood work.

For injections, I can see the argument, but most of us aren't injecting anything (with the exception of those getting iron infusions, which I'm sure they know will affect their iron readings in labs depending on how close the infusion is to their lab draw).

I've never had a dietician recommend stopping oral supplements prior to labs, and when I've asked them about the issue specifically, they agreed that you shouldn't care what your levels are WITHOUT the supplements unless you plan to stop taking them. I didn't stop my vitamin D prior to my last labs, and my D level came back as 32, so if that is a "false elevation," then something is wrong (I only have about the same amount of intestinal malabsorption as a proximal RNY and was taking 50,000 IUs vit D every other day - now every day).

In the end, do it however you want, but be sure to be consistent about it so your labs are trackable for trends.