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dd4L · May 16, 2015, 12:09 AM

If a home drug test yields a negative result, is it possible that the same test on the same day performed by a lab could yield positive?

Fr_Chuck · May 16, 2015, 12:25 AM

Yes it is possible, different standards and also levels of reliability. Thus he reason home tests are not accepted in court.

Luck0rN0t · May 16, 2015, 12:39 AM

Certainly. What was the cutoff for the home test vs. the lab test? When was each one done in relation to the other? Did you drink an excessive amount of water? What are you being tested for? Why are you being tested? Depending upon what they are looking for, labs have much more sophisticated testing equipment than a cheap drug store test.

First void of the day usually will result in the highest concentration of <your drug of choice> whereas drinking excessive amounts of water can cause you to fail for dilution. Too many factors, not enough info.

If you got popped and are expected to abstain, that would likely trigger a different cutoff than, say, pre-employment drug testing. From what I have read, confirmation testing is usually only done when a positive result is shown, but a lab always has that ability, which will yield much more accurate results.

talaniman · May 16, 2015, 05:51 AM

Home tests are NOT the same as a lab processed test. Not even close. Could the results be different? Definitely! Home testing kits are marketed to people who need a false sense of security in beating the LEGAL testing system.

dd4L · May 16, 2015, 11:32 AM

Originally Posted by Luck0rN0t

Certainly. What was the cutoff for the home test vs. the lab test? When was each one done in relation to the other? Did you drink an excessive amount of water? What are you being tested for? Why are you being tested? Depending upon what they are looking for, labs have much more sophisticated testing equipment than a cheap drug store test.

First void of the day usually will result in the highest concentration of <your drug of choice> whereas drinking excessive amounts of water can cause you to fail for dilution. Too many factors, not enough info.

If you got popped and are expected to abstain, that would likely trigger a different cutoff than, say, pre-employment drug testing. From what I have read, confirmation testing is usually only done when a positive result is shown, but a lab always has that ability, which will yield much more accurate results.

Substance used was 10mg Adderall on Wednesday a.m. home test was negative on Friday at 6pm. Took lab test at 7:45pm. I don't know cut offs, the program uses quest diagnostics .
Thanks

dd4L · May 16, 2015, 12:55 PM

Originally Posted by dd4L

Substance used was 10mg Adderall on Wednesday a.m. home test was negative on Friday at 6pm. Took lab test at 7:45pm. I don't know cut offs, the program uses quest diagnostics .
Thanks

I looked into it and both companies use 1000ng/ml. So do you think I'm clear?
Thanks

tickle · May 16, 2015, 01:14 PM

NO, of course not. There testing methods are well above standards you would use at home.

Luck0rN0t · May 19, 2015, 11:59 PM

I am not a drug testing expert by any stretch of the imagination. I only like to research online. From what I have found, 1 - 4 days is common for the drug to stay in your system. Many reports say 24 - 48 hours. It is certainly in your favor that a home drug test came out negative and you have over 48 hours.

I have used home drug tests for marijuana and the results were pretty spot on with the lab, but that means little to nothing to you. Also, the home test did not test for dilution - a huge red flag in real world tests.

If I were you, I would feel like I had a better than 50% chance of passing, but it really depends on how hard core they are on the testing - if confirmation is used - that would be bad news for you. It *seems* like most home tests tout 1000ng/ml cutoff, as well... but again... much lower testing standards.

Sounds like you were in the best possible position, given the situation - testing that soon after the home test, but you certainly can't count on the lab coming up with the same result, by the very nature of the testing accuracy between the two.

dd4L · May 20, 2015, 11:40 AM

Thank you for the info.

dd4L · May 20, 2015, 11:53 AM

Originally Posted by Luck0rN0t

I am not a drug testing expert by any stretch of the imagination. I only like to research online. From what I have found, 1 - 4 days is common for the drug to stay in your system. Many reports say 24 - 48 hours. It is certainly in your favor that a home drug test came out negative and you have over 48 hours.

I have used home drug tests for marijuana and the results were pretty spot on with the lab, but that means little to nothing to you. Also, the home test did not test for dilution - a huge red flag in real world tests.

If I were you, I would feel like I had a better than 50% chance of passing, but it really depends on how hard core they are on the testing - if confirmation is used - that would be bad news for you. It *seems* like most home tests tout 1000ng/ml cutoff, as well... but again... much lower testing standards.

Sounds like you were in the best possible position, given the situation - testing that soon after the home test, but you certainly can't count on the lab coming up with the same result, by the very nature of the testing accuracy between the two.

Thank you for the info. I have researched and found that both tests are performed by immunoassay technology. The lab will send for confirmation only if initial screen is +. Apparently there are different types of immunoassay tests and I haven't been able to find out which specific type first check home test uses. It does appear that both companies have a very similar methodology for the initial screen. Both labs use the same method to confirm a preliminary positive screen which is a more advanced technology. So at this point I have not been contacted which would occur if +. I really appreciate your input.

Luck0rN0t · May 20, 2015, 06:41 PM

So at this point I have not been contacted which would occur if +.

I agree - I think you would have certainly been contacted by now it you had a positive result and even if a confirmation was done. Sounds like you are in the clear on this one, congrats! While I would not bet my life on a home test, I think they are a good marker - I use them on my teenage daughter by surprise and I trust the validity for that purpose. ;)

I hate to give false hope when people's freedom/jobs/family are on the lines, so I tend to try to err on the side of caution in offering my opinions and experience.

Best of luck going forward!