B6 blood vial not protected from light - what happens?

My own b6 level came back very high, and I was just taking a generic B-complex. I have read here several times lately that others had high b6 levels.

Some one had speculated that maybe the vial wasn't protected from the light after the blood draw (as they should be).

Does any one know if not protecting the vial from light would give a falsely positive high reading for B6? Would it just ruin the sample, and then not give a reading at all??

I'd like to figure this out before I go messing with my B vitamins, and really mess things up.

*sigh* I know everyone loves when I play devil's advocate, but it really doesn't matter.  The reality is that they cannot cover the tube while they are drawing your blood.  The phlebotomist has to be able to see the blood flowing into the tube to ensure a good blood flow, volume and integrity.  Once the tube is filled and completely labelled and checked they can then wrap it in a glove or aluminum foil to send it to the lab or put in the fridge/freezer, but here's reality.  Once it arrives in the lab processing area, any lab processing area, it is going to be exposed to light.  The sample has to spun down, the labels have to be checked and rechecked, the plasma has to be poured off and then it will be put into a rack to be sent out or for testing.  There are only a couple of truly light sensitive tests out there and they require the patient to be drawn at the site of testing and the specimen to be drawn and run immediately.  The rest of the tests that are labelled "light sensitive" are just not that sensitive and in all cases exposure to light may cause a slight drop in analyte level, not a rise.  We have done study after study in my lab running specimens at different times of light exposure and I have NEVER seen it affect the results of any test.  The truth is one of the most sensitive of all lab tests is the bilirubin which is part of any complete metabolical profile (one of, if not, the most common test run) and no EVER protects these from light.  It is way more sensitive than any vitamin.  So I think it's great that everyone here is so proactive about knowing their blood test requirements and reminding phlebotomists to please wrap their tubes because if it's just going to sit on counter for 30 minutes, yeah wrap the thing, but once it leaves the drawing center it is going to be exposed to light.  There is not avoiding it.

Laura MT (ASCP)

The reality is that they cannot cover the tube while they are drawing your blood. 

That isn't true.  I have my blood drawn at my doctors office all the time for vitamin A, D and K all the time and they cover it in foil prior to drawing.  They put the label on top of the foil.  From there, they transfer it in a dark room into a brown tube so it is protected from light the entire time and they do this at my local lab as well.  I have see it done.  Then it can be sent to the processing lab and it doesn't matter how much light there is because it is in a light protected tube.

How do they know when the tube is full enough, just peel back and take a peak?  They centrifuge it in a dark room?  They remove the plasma from the red cells in the dark?  They have to be able to see this.  We have those brown tubes too, they are great for transport, but they can't be put on any analyzers so it's going to be put back into some kind of standardized clear tube.  Then it will be run on the instrument which may or may not be light protected depending on the testing method.  Every lab I've worked at, especially reference labs stores their specimens to be tested in large racks either in processing or at the area of the lab where they will be tested and none I've ever seen have racks that are light protected.

Best case scenario you get great attention at the drawing site like in your case, great shipping, even if they leave it in the brown tube until right before testing (which NEVER happens because these are batched). It will be exposed at some point for some time.  I completely agree about minimizing this when possible, but I've seen and run specimens handled under cir****tances you wouldn't even dream of.  "Can you run this we found it in a puddle in the parking lot where it fell out of the currier van?"  "Yeah, this tube was drawn yesterday and got stuck in the tube system is it still good?"  "The patient accidently took his urine home yesterday and brought it back, can you run it"  I have seen it all.  There are very very specific requirements for every test and even if we can't report out the results we will always run it and log it in our "problem" specimen file as a learning tool for just these weird things so that when we have educationals for the phlebotomists we can pull out real data and show them what happens when.  Again, I just haven't ever seen a test that was truly affected enough by light exposure to make me nervous and I am a FREAK when I or my loved ones get blood drawn.  I am truly a phlebotomist's worst nightmare because I know the crap that will REALLY mess up a test.  If you're watching to make sure your vitamin level is being light protected and they draw your tubes in the wrong order it is a WAY bigger problem (the additives in the purple top tube used to draw a CBC (H&H) will REALLY mess up your CMP as one example, another is how long they leave the tourniquet on or if you pump your fist, those both elevate your potassium, I have seen this time and time again and it's really hard to quantify and avoid. Plus if you're actually running a low potassium, which is just as bad if not worse than a high potassium, an elevated potassium due to a bad draw will come out as "normal" and never be caught by the MT).

Again I'm not trying to be controversial.  I'm just trying to be helpful.  If you don't disagree feel free to call me a quack and walk away.  I have thick skin.

Laura

Hi Laura,

Thanks for the explanation.  As a former labrat, I know how these are batched.  Even though my pre-op B6 was way high, I was not suffering any neuropathy symptoms.  Seeing that other people's B6 tend to run high, I'm going to chalk it up to lab processing and keep an eye on it from now on.  Good thing it's not as crucial as monitoring D and Ca after post-op.

Hugs,
Ratkity

As far as drawing the blood, they say they know how much time it takes to fill a tube after drawing so many vials of blood. My doctor has a lab in her office and they don't get sent out.  If they are that careful to draw it correctly, I would think that they would process it correctly.  The doctor and lab technician were all mortified when I told them what happened to me when I went to quest and the tech refused to cover the vials in foil.  I came to her office and she redid the tests and there was a huge difference in the results.  So, you can't convince me that there isnt a difference.

Your Dr has a machine that monitors B6 levels in her office?  I didn't think there were any POCT (point of care testing) analyzers that did vitamin levels?  Can you confirm this?  Can you give me any information about where you go or how to get ahold of someone at their office?  Our POCT coordinator would love to know about this.  With the demand for D testing, a POCT vit D test would be a great thing to know about.  We've been trying to get a Vit D analyzer for a year now and they are just so expensive and so high tech that we can't justify the expensive and we do about 1500 samples/day.

Laura

My doctor used to do the vitamin D but the last time she sent it out. She always sends out the vitamin A, K, E, selenium, magnesium, zinc and B1.  I have never had B6 drawn.  She does do the B12, iron studies and folate. 

Foil wrapped during draw is possible!!!

I have my labs drawn foil wrapped! The Phlebotomist told me that she "counts" how long it takes to fill a couple vials then does the wrapped one. I dont have the link and right now too lazy to look for it, but it says that the blood has to be light protected from draw until it goes to lab for processing.

The trick is to find a good phle. and stick with them.

All the literature and test requirements for a lot of tests will read "protect from light".  I'm not denying that at all.  I'm just trying to give an insider's perspective.

Foil wrap during draw is possible for a good phlebotomist and a patient who's easy to draw, but when I draw from someone with small fragile veins I often have to watch the blood flow and adjust the depth of the needle or the angle to keep it flowing smoothly.  I also have to make sure that the blood is mixing with the additives in the tube.  Not an issue with an easy draw but impossible with some.

To put it in perspective there are several tests that absolutely have to be kept cold from time of draw to being put in the freezer or analyzed.  Some even require using pre-chilled tubes, but the reality is very very few collecting centers or even moderate size labs have refrigerated centrifuges so the sample is going to warm up during the 5-10 minutes it needs to spin.  It doesn't mean you don't try it just means that nothing is ideal.

Laura