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False negatives...Pitfalls of Urine Drug Monitoring in Pain Care ...

Aug 09, 2010 - 9 comments

False negatives...Pitfalls of Urine Drug Monitoring in Pain Care ...

I am always looking for information on the effectiveness and accuracy of the drug test we have to endure. I have just come across this one from Early this year.
It has alot of information on how the UA works and why they are inconclusive most of the time.
I am including the link as I have not posted everything in the article.
The VA study I have posted in my journal and refer members to was done in 2004 I believe. I continue to look for updated material on this as we do get members who have to deal with the mysterious results of a false negatives alot.
I will also post this link in the health pages and journal for future reference.
I have several other studies I am looking at also that addresses false negatives.
With so many having to deal with this problem I try and keep the newest information up here in the community.
When someone has received a false positive it is good to have reference material to do to the doctor with and show that this is an all to common problem.
I do hope it will help someone:)

Drug monitoring in pain practice is often a two-stage process [Leavitt 2005]:

A.Preliminary Screening of patient-provided specimens, usually urine, at the point-of-care (POC) to detect the presence or absence of a limited number of prescribed and non-prescribed drugs of interest. The accuracy and reliability of relatively inexpensive POC screening assays are limited; although, more costly laboratory-performed assays can be of higher quality.


B.Confirmatory Testing techniques, using high-quality methods (eg, GC-MS, LC-MS), are more expensive but highly accurate and reliable. A problem is that these methods sometimes can be too good, detecting small amounts of irrelevant agents or metabolites that are diagnostically unhelpful or confusing.



While it would be presumptuous to caution against the use of urine drug monitoring, there are a number of potential pitfalls worth noting. Here are several common as well as less well-known considerations:

•Detection cutoff-levels do not always take into account passive (innocent) exposure to marijuana or cocaine consumed by others, consumption of poppy seeds (natural opiate), and the use of OTC products that may cross-react with the assay to produce false results [Evans et al. 2009; Reisfield 2009].


•A number of opioids are metabolized by liver (CYP450) enzymes: eg, codeine, hydrocodone, oxycodone, methadone, buprenorphine, tramadol, and fentanyl. Individual patients may have genetic variants of the enzymes, or may be taking inducer or inhibitor drugs, that strongly influence opioid metabolism and, hence, their detectable presence or absence in urine (or blood, or oral fluid if used) [see, Carlozzi et al. 2008; Smith 2009]. For example, the unexpected absence of one of the above opioid analgesics upon testing can be due to rapid metabolism in a patient rather than therapeutic noncompliance or drug diversion.


•Morphine preparations typically contain low levels of codeine as an impurity, which may be detected by high-quality assays in patients who have not been prescribed codeine [Evans et al. 2009].


•Patients prescribed high doses of oxycodone also may test positive for hydrocodone, which is believed to be present as an impurity; analytically this is a true positive, but diagnostically it is a false positive [Evans et al. 2009].


•It has been clinically observed that unanticipated conversions between opioids going beyond common metabolic pathways may occur, and these can be detected by high-quality assays [Haddox 2005]. For example, patients prescribed only codeine might test positive for codeine and morphine, and also hydrocodone and hydromorphone. Patients taking only morphine might also test positive for hydrocodone and/or hydromorphone. While mechanism behind this metabolic phenomenon are not understood, such findings could falsely suggest that patients are taking unauthorized opioids.


•Proprietary, computerized methods have been developed for quantifying the amount of opioid agents in testing samples; these have been based on controlled conditions examining carefully-selected patients [Couto et al. 2009] or pharmacologically adjusted values [Kell 1994, 1995]. Relying on quantitative tests to help determine whether a patient is properly taking the specifically prescribed dose of opioid can be questionable, especially in patients who do not fit typical patterns of metabolism or have other confounding factors. Due to their limitations, quantitative assessments have been eschewed by government agencies where the consequences of misinterpretation could be severe (eg, Drug Courts).


•Even the most high-quality laboratory testing may not deter persons seeking opioids for illicit purposes — they know how to cheat. An entire industry has sprung up offering advice and products to “beat the test” (just insert that phrase into any search engine to see the myriad of solutions being promoted).


•Case reports have noted false-negative results for opioids and cannabinoids in the presence of tolmetin, an NSAID, and for amphetamines due to interference by chlorpromazine (eg, Thorazine®) metabolites. The antifungal agent fluconazole may interfere with the detection of cocaine [Reisfield 2009]. Persons determined to “beat the test” may know about this.


•A popular and effective way to beat the test is by substituting “untainted” urine for one’s own by carrying a concealed specimen into the bathroom. The only way to thwart this is by supervised urine collection (ie, a staff member observing urine leave the patient’s body and fill the cup). While this is required for forensic urine testing, it could be the ruin of a typical medical practice; it is upsetting for patients and demoralizing for staff.


•To avoid the possibility of urine specimen substitution, oral fluid can be collected for use with screening devices employing technology similar to on-site, POC urine screens. Sensitivity and specificity of oral fluid screening and testing are acceptable, but subject to the same limitations of interpretation and confounding factors as urinalysis [Leavitt 2005].


•Urinalysis is unhelpful for detecting alcohol misuse or abuse [Moeller et al. 2008], and alcohol can be more hazardous in combination with opioids than many other drugs.

The above list is certainly not all-inclusive [eg, also see, Carlozzi et al. 2008; Reisfield et al. 2007b]; however, in view of the many caveats, healthcare providers may want to reconsider what they expect to accomplish by drug monitoring as a component of pain care and if it will adequately serve them and their patients

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1417952 tn?1282184460
by UnfortunateHonest, Aug 18, 2010
Thanks VERY much; this false negative methadone urine test results from the cup are scaring me. I had finally gotten my life back after nigh bankruptcy & surgery & countless epidurals, NOW with this simple & affordable pain management treatment that still works going on, soon, 2 years into it with the same dosage (in fact decreased 25% early on by me willfully experimenting on my own without being lowered by the Dr. first or forcefully). It is off for lab testing... cross your fingers for me & thanks for this info.!!!

Avatar universal
by bbg231, Feb 26, 2011
I suffer from chronic back and body pain for 3 yrs they have had me on percept while they keep testing me for why this is happening to me. This pain has ruined my daily life also putting  extending my family on hold.I broke my back in a car wreak had medal put in then later removed. Today I went to my dr. at the pain clinic he gave me a random urine drug test to make sure I'm taking my percept I of course had no problem with this cause I take my meds as percribed I had even taken a half of a percept in the waiting room.before that 1 three hours earlier.Well I was shocked to hear that my test was negative. I was so upset as they accused me of selling my pills.I asked them to repeat the test they did 3 times How is this possible? I asked them to take blood, hair, spit anything to prove I take my meds as percribed 5 to 6 a day.I even offered to pay for the test they said no but did say they said they will send the original urine to the lab but if thats negative I will be dropped as a paitent,The only other meds I am taking are the following ciprofloxacin xl 500mg,lansoprazole 30mg witch is genaric prevacid,aviane21 witch is birth control, prozac10 mg Does anyone know how this could happen!!! This is just so awful finally I find a doctor who is helping me and giving me other therepy than just pills now this. I called them after going home a crying my eyes out I called the office and asked to please make sure they are testing me for percept not oxys cause the tests are different witch I found out after calling a lab tec the doctor got mad at me and said he knows how to do his job.I want to clear my name this is so unfair.

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by ladyecho, Mar 24, 2011
Oh how I know the feeling!!!

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by mountaindove, May 11, 2011
I was in a car accident back in 2007, and broke my neck at c1-c3 spine damage at c5-c7 and also was on oxycodone. My surgeon  turned over my med care in 2008. I have been on everything you can think of but this past year was put on the oxycodone and given 180 per month. Now anyone that understands my injuries knows I had to be taking my meds. I suffer from neuropathic pain. At that time I was also in pt 3 times a week. To make this short I also had a urine test that came back neg. OMG how could this be true. My doctor had her office manager call me and cut me off cold turkey and kick me to the street. I ask for meds for withdrawls only to be told I don't need them as I must of been selling my meds and not taking them. I can't believe that some doctors today have not a clue of whom their patients are. If a doctor does not know their patient after 5 years etc. then they are not taking enough time with that patient. I am so bitter over this and have not a clue of what to do. My main concern is to clear my name. If anyone has any information on how I can do this please contact me at :***@****    I have been thru hell since this accident that I had no control over. I was hit from behind while I was waiting to make a left turn from a suv doing 75mph. This BS that my past doctor has accussed me of  and I am being labeled gulity! Please if anyone can help contact me. Good Luck everyone.


9501656 tn?1404649387
by Diamond_Dixie, Jun 30, 2014
A chiropractor adjusted my life in 1997 - he broke my back. I take heavy-duty pain meds, which make me "normal," not "high", not a single little bit. I just showed a false positive for Klonopin today in my monthly urinalysis test. Two months prior, unfortunately, I had a legitimate positive, to which I immediately admitted. I had taken a SINGLE dose of an old (ancient) prescription - mine, of course - for this med a full 7 days earlier during a kidney stone  event coupled with a newly diagnosed interstitial cystitis flare-up. I admitted to my (oh, horror!!) singular indiscretion taking responsibility. This time? NO WAY. There is NO WAY I would further jeopardize this particularphysician's ability to treat me, and had turned in the remaining medication in my possession. Yet of course, this is now on my record with him. I am shattered, but fortunate he did not discharge me. Yet. WILL A FALSE-POSITIVE HAPPEN AGAIN?? During the last 6 hours I have been reading and compiling information on the incidence of false-positives related to this very situation and medication. I'm stunned. How in the world can this not be well-known in the medical community...it MUST be. Why, then, are people simply thrown aside, their lives left in shambles, following false-positives for oh-so-many prescription drugs and (some, only currently) illegal drugs? The pain management industry is so difficult these days, demoralizing, invasive and simply inhumane most of the time, and we who must ascribe to this humiliation are further chastised and unduly thrown away - when we desperately need help to function. I am fortunate to still be under the care of probably the best physician I have ever had for this condition in 15 years. There are so very many of us who are not as fortunate as me. HOW CAN WE COMBAT THIS EXTRAORDINARY AND LIFE-ALTERING UNFAIRNESS, PROPAGATED BY THE WRONG AGENCIES and MEGA-CORPORATIONS, WITH ABSOLUTE SECONDARY MOTIVATION?? Please respond, any of you who want to be heard. ALL RESPONSES REFERENCE THIS TRAGEDY SHALL BE HELD IN UTMOST CONFIDENCE. Be well, all.

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by nursenana05, Nov 03, 2015
I worked at a surgery center and just tested positive for fentanyl. I do not use fentanyl have never used fentanyl but I give it to patients all day everyday. 2 days before the test I had a syringe de-plunge in my pocket while helping a patient up. another nurse witnessed this and we marked it down as a waste, not think thinking another thing of it.  but this sat on my skin for 36 hours, (both on my breast itself and in the fabric of my undergarment that had absorbed the fentanyl that I wear 24/7) When I told the drug screening place, who called to find out what meds I take, about this incident, he was unsure about this kind of exposure. He said he would check on it and let me know. Well he didn't he called my work after he hang up with me and told them I tested positive. I now have no job and am about to be investigated by DOPL. I'm scared, mad, and so unsure as what to do. Any Ideas?

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by Rychasky, Aug 18, 2016
I have taken yellow norco for over two years, they no longer carry that drug so this past month I had received the white norco 10/325 & I went to my doctor yesterday he told me I tested positive for oxocodine that I have never taken. How is this possible nothing has changed in my medication but the norco. I need help finding the answer please. Ty!

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by BAMADIAMOND, Oct 30, 2016
BAMADIAMOND..........   Oct.29, 2016                                                                                                                                                                           I was told at my pain clinic yesterday that two months ago I tested negative for my Klonipin, which I take 2mg every night for restless legs and cramps. Then he tells me last month I was negative for my Hydrocodone 10/325 I take 4 times a day, and negative for it yesterday and was told I could no longer come back. I've been with this group for ten (10) years. I got better from a surgery I paid cash for, because it was not approved by insurance. So in six (6)weeks time I felt better, totally weaned myself off slowly of these, at that time , Hydrocodone, Fentanyl 100mg every other day patches, Indomethocine 300mg 3x day, valium......Told them thanks and I didn't need them anymore, 2006. Years later about four(4)years ago I tore my ligaments in my left ankle up to my knee, then my left rotator cuff, now my right, all the back pain is back with increased disc involvement. So nothing has been repaired Surgerically to my shoulders, left foot, or back, I'm now without pain meds. I've never been short, never later, never caused a problem, and was reminded of that. Then the Doc had the nerve to refuse me blood test, another urine test, the nurse said nurses never make mistakes because the bottle has our name on it, LMBO. The Doc had the nerve to say well here is a RX for forty (40) hydrocodone 5mg/325 to wean you off for the month till you find another pain clinic. Question, " if it's not in my system, (per him) why do I need weaned off??????       Why is all of these patient's all of a sudden being accused of lying with proven, legit broken bodies? We have x-rays, MRI´S, lab's, all that to prove we are in pain.

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by LynnX123, Aug 22, 2017
This happened to me too. I was negative for methadone. I asked to see the labs. The methadone metabolites were there however they were below the threshold they use for it to be called a positive. I was so furious as I know I had been taking my dose everyday faithfully. I went to another clinic and spoke to the Dr. and nurse and they thought the other clinic was rediculous. To showed them the labs and explained to them I had a physically demanding job and they concluding I was metabolizing it quickly because of how physically demanding my job was. Thank goodness I found a new place to go. The medical establishment needs to be educated on this.

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