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False positive for cotinine
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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!
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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.
 
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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?
 
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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.


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