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False positive for cotinine
marathonjan posted:
I'm a bit distressed, I am a confirmed non-smoker -- have never smoked, can't stand to be around cigarette smoke, and am not at all exposed to second-hand smoke, either at home or at work. However, after having blood drawn for my annual wellness test at work, I tested positive for high levels of cotinine. The test was repeated and the result was the same!

I've been doing a lot of research to see what could cause a false positive, and have read that certain foods in large quantities (almonds, mustard, broccoli, tomatoes, potatoes) could yield a false positive... but I've consumed none of those in large amounts.

Can anyone shed any light? I really don't want my medical file to look as if I smoke heavily, when I've spent my whole life avoiding cigarettes!! I do sometimes light candles in my house, could that have this affect?! Grasping at straws!
Jonathan Foulds, PhD responded:
Cotinine is the main metabolite of nicotine. This may sound obvious, but nicotine can be absorbed from smokeless tobacco, (chew, snuff, snus etc), cigar, pipe and hookah tobacco and also from smoking marijuana if it is mixed with tobacco (e.g. as in a blunt). Nicotine is also absorbed from electronic cigarettes and from nicotine replacement products (gum, patch, lozenge etc). So the first step is to check that you hadn't used any of these products around the time you had the blood sample.
marathonjan replied to Jonathan Foulds, PhD's response:
Thanks for your response, Dr. Foulds. No! I've never used any nicotine replacement products because I've never smoked, and I've likewise never smoked pot as well! As a marathon runner, I train nearly every day and don't want any odd substances in my body, LOL.

I've washed my face with Noxzema every day since I was 13, and I know it contains menthol and camphor. I realize I'm just grasping at anything here, but could something like that cause a false positive?
Jonathan Foulds, PhD replied to marathonjan's response:
Could you enquire about exactly what they measured, in what body fluid, and exactly what cotinine concentration you obtained? If you were just above the cut-point it may make sense to consider some kind of unusual exposure to nicotine 9although it sounds like you have ruled this out). But if you have high levels that is just weird and I would recommend going to a different testing center and having the test carried out independently. In my experience it is extremely unusual for a never tobacco user to test positive for cotinine when tested at a reliable lab.
chadveach responded:
Did you have any luck figuring out the false positive issue? I've found myself in the exact same situation with two qualitative cotinine tests for my employer's healthcare program with no tobacco or nicotine use ever.
marathonjan replied to chadveach's response:
Hi, chadveach, no, I have not resolved this!

My company test was done at Quest Labs, which I have always believed to be a fairly reliable lab. My GP knows that I am a non-smoking athlete and feels like I should just put the whole thing out of my mind and not stress about it, but I hate having anything in my file that could portray me as a smoker, when I have been so adamantly anti-smoking for my entire life! Also, if there really IS nicotine in my body for some reason, might this be harmful in some way?

As Dr. Foulds suggested, I asked my GP about conducting an independent test, but she felt that urine and follicle testing were even less reliable than the bloodwork; in her opinion, I should just forget the whole thing. Still bothering me, though, and I unfortunately opted out of doing my company wellness testing this year, as I worried that the false result would be repeated!
annb46 replied to marathonjan's response:
This is currently my situation as well. Two false positives at a quest lab. I haven't smoked in over 20 years (dumb 16 year old and at most 2 packs over a summer). I'm getting a third test done tomorrow at a non-quest lab. Very frustrating to say the least!
marathonjan replied to annb46's response:
Annb46, I've read that cotinine passes from the body within a couple days of exposure, so you're definitely not seeing effects of any brief smoking you did 20 years ago.

Please let me know how you make out after the third test, and what kind of testing you do at the non-Quest lab! As you say, it is very frustrating to be portrayed as a smoker, so I'm wondering about potentially re-testing as well.
marathonjan replied to marathonjan's response:
Hello to all on this chain!

Success! In conjunction with my annual physical this year, my GP prescribed a retest for cotinine for me, because she knew how distressed I was with the false test results obtained through my company testing via Quest. (I am an athlete who has NEVER smoked and am not exposed to second-hand smoke.)

This was once again blood testing, but conducted through LabCorp this time. Result: ZERO evidence of cotinine in my system! NO IDEA what would have caused the wildly incorrect results from earlier Quest testing, but I am very gratified to finally have a correct test result.

I work part-time for a couple gyms and they are starting to screen for cotinine levels, as they don't want smokers on-staff. And, of course, companies are screening for it as well. So I was floored and mystified by the earlier Quest results, and it was critical to me that I have some sort of proof (out in the Cloud) that I am in fact a confirmed non-smoker!

For those of you who've received weird cotinine results, I encourage you to have your doc prescribe a re-test at a different lab.

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