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Family Physician
Family Physician, Board Certified MRO
Category: Drug Testing
Satisfied Customers: 12816
Experience:  Medical Review Officer - Physician Trained and certified in drug test interpretation
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Subject took a UA, a 10 panel hair test, and a 10 panel nail

Customer Question

Subject took a UA, a 10 panel hair test, and a 10 panel nail test all at the same time. The UA and hair test came back negative for everything, but the nail test came back testing positive for cocaine 3,400 pg/mg (not a metabolite). Is it possible that the specimen was contaminated? Subject admits to using heavily over two weekends approximately 5 months ago, but has since stopped. Is this an accurate reflection of these tests?
Submitted: 1 year ago.
Category: Drug Testing
Expert:  Dr. D. Love replied 1 year ago.

Hello from JustAnswer.

If I understand you correctly, the level of benzoylecgonine in the nails was zero, correct?

Was the benzoylecgonine listed separately and stated to be a zero level?

Expert:  Family Physician replied 1 year ago.

Thank you for your question - I am one of the drug testing experts, I will be happy to help you.

The detection period for hair testing is only about 3 months, so having a negative test is to be expected. The detection period for nail testing is however longer - typically about 6 months. The fact that there is a positive nail test may reflect the heavy use that you reported 5 months ago.

The other possibility is external contamination (particularly if the person was around cocaine - even if they did not use it) in the last few days, since some could have found its way under the edge of the nail. The fact that there is no metabolite identified, might support this interpretation. The other explanation would be the benzoylecgonine (cocaine metabolite) is present, but at a level just below the level of detection for this particular nail test.

Expert:  Family Physician replied 1 year ago.

I hope this has been helpful.