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Reasons for F-Neg. Tests???

Yesterday, I had a real shock upon being given a false-negative outcome for, oral swab test for my meds. I take percocet & opana, alternately. I may have posted this question incorrectly on this site (last nght), as I was so upset and worried... how will I cope with my terrible pain. I was given another urine test, but I am still wondering how it will all turn out, as I'd taken my med almost 4 hours before. I also have had gastric bypass surgery, and wonder if this may effect my results??? Please respond, if anyone can help. Thank you.
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547368 tn?1440541785
I am just checking in to see how you are doing. I've been very concerned.

You have no reason to feel ashamed... this happens to the best of us. PLEASE let us know how you are holding up.

My Best
~Tuck


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356518 tn?1322263642
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356518 tn?1322263642
You should not drink Grapefruit juice with any time release medication and many others also as it breaks down the medicine quicker giving you more than you would normally get.
There are research studies done on False negitives and articles on the subject. There are so many factors that you can not really pin the problem down to one specific one.
I would definalty start looking for a back up as you may be released from your current Doctor's care.
If the Doctor is willing he can order a hair scan which will tell him all the drugs in your system within the last 60 to 90 days. You can also order one yourself online.
I wish you luck. I have been there and went thru this and it is horrible!
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Avatar universal
Thank you also (just wrote to "Tuck"... I am so stressed out, I feel ill. You folks are kind... I just hope this test has mercy for me... and I may be able to re-establish w/ my Doc. I feel ugly and embarassed to face everyone in the PM office now. What a horrible predicament... the pain, now this!
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Avatar universal
Thank you for some hope... the Doc wanted to immediately rlease me, w/out any if's, &, or but's... I had to "beg" for the urine test. I have also been drinking a lot of grapefruit juice, and someone on this site wrote about this (I did not understand the terns though), and the urine test was given almost 4 hrs. after a med, the first of the day (none taken over the night before)... yes, I am very upset, worried, and angry. What will happen to me, I'm in very bad shape.
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547368 tn?1440541785
Hi Ms Eva,

I am so sorry to hear about the results of your drug screen. A oral swab or saliva drug screen is the least accurate of all the drug screens. It's used because it's the least costly.

So many things can change or interfere with the outcome of these oral swabbing. ....Even eating certain foods can alter the production of saliva. Smoking is also believed to mask the metabolites needed for drug determination. I wouldn't be overly concerned with the outcome of this particular test. I'm hopeful that your urine drug screen will be more accurate. I know it's difficult but try to relax until the results return from the second testing.

I lost over 3 ft of my small intestine in a MVA. That is the area of your intestine that absorbs much of the nutrients required for good health and it can disrupt absorption of some medications. This is similar to some gastric by-passes, mostly the older ones. My point is this can interfere with drug testing according to my PMP. He is aware of that fact and would take that into consideration IF my drug screens didn't return as they should. Drug screens terrify me, not because I don't take my meds as ordered but because of my condition and all the horror stories I hear on this forum. I feel your pain and concern.

The worse that could happen... that's how I look at it... is that you would have to find another physician. This might take some time so begin searching for a back up right away so you'll be ready to make some calls if necessary.  However even if you are negative in the second test your physician may be very understanding. Urine drug screens are not always accurate either. Most physicians know this fact and take this into consideration. But know your clinic's rules and regulations.... and how they handle any false returns.  

I discussed my concern/fears right up front with my new PMP. He assured me they would not automatically " kick" me out.... unless they found illicit, illegal drugs in my screens such as cocaine, even then they refer those patients to a counselling PMP.

As geminigirl said there are a lot of older post on this subject in our archives. Please don't hijack one and "post" on them. Please use them for research and information. New posts on old threads are often ignored. You'll obtain better responses by doing just what you have done... beginning a new thread (question/post).

I wish you well and hope that you will let us know how this turn out. We'll look forward to hearing from you again soon.

Best of Luck,
~Tuck
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Avatar universal
I'm afraid I can't comment with personal experience, but I do remember reading several posts on here about people who have had gastric bypass surgery having difficulty with getting false results on their urine tests - something to do with their absorption of teh meds since their surgery.

The timing may also have had something to do with it, depending on how often you normally have to take your meds.  You mentioned it had been about 4 hours since you had take the meds - when would you have been "scheduled" to take another dose?  If it would be right around that time (or even within a couple of hours maybe), I would think that may also have had something to do with the false negative - especially if you experience any type of "dumping syndrome" since your gastric bypass, meaning things that enter your stomach get "dumped" into the intestine quicker and don't get absorbed (or at least not as well)

Maybe try doing a more extensive search here on medhelp to find some of those older posts I'm referring to or even a google search on absorption of oral meds folllowing gastric bypass.

I believe I also saw where you had "piggy-backed" on another posters question/comments and you mentioned that you had been drinking a lot of grapefrut juice?  Some medications to not mix well with grapefruit juice and it can affect the levels of meds in your system (either higher or lower).  A good site that I use quite often to check for interactions, side effects, things I should avoid while taking a med, etc. - is drugs.com (of course, use the www. first) - you can enter the name/s of your meds and pull up lots o finformation on them as to what side effects to look out for, foods or other meds to avoid, etc.  I typically visit that site any time I get a new medication - I know you get some information from the pharmacy, but I've found that this site goes more in depth and has much better information that those little pamphlets!

Best of luck!
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