Intentional Adulteration of Urine Specimens for Drugs of Abuse Testing to Produce False Positive Results

1990 ◽  
Vol 14 (3) ◽  
pp. 195-196 ◽  
Author(s):  
C.A. Johnson ◽  
P.L. Cary
Keyword(s):  
False Positive ◽  
Drugs Of Abuse ◽  
Positive Results ◽  
Urine Specimens

Investigation of interference by nonsteroidal anti-inflammatory drugs in urine tests for abused drugs

1990 ◽  
Vol 36 (4) ◽  
pp. 602-606 ◽  
Author(s):  
D E Rollins ◽  
T A Jennison ◽  
G Jones
Keyword(s):  
False Positive ◽  
Drugs Of Abuse ◽  
Fluorescence Polarization Immunoassay ◽  
Dosage Regimens ◽  
Chronic Ingestion ◽  
Inflammatory Drugs ◽  
Anti Inflammatory ◽  
Abused Drugs ◽  
Positive Results ◽  
Test Result

Abstract Anecdotal and uncontrolled studies have suggested that nonsteroidal anti-inflammatory drugs produce false-positive results in immunoassay urine tests for some drugs of abuse. This study was performed in 60 volunteers who took ibuprofen as either a single 400-mg dose, or 200 mg three times a day, or 400 mg three times a day, and in 42 patients taking ibuprofen, naproxyn, or fenoprofen in therapeutic regimens for more than 30 days. Of the 510 urines collected from 102 individuals during these dosage regimens, two gave false-positive tests for cannabinoid by enzyme-mediated immunoassay (EMIA), one after 1200 mg of ibuprofen in three divided doses for one day and one in a patient taking naproxyn on a chronic basis; none was falsely positive for benzodiazepines. Two urines were false-positive for barbiturates by fluorescence polarization immunoassay (FPIA), one in a patient taking ibuprofen and one in a patient taking naproxyn. These data, collected prospectively, demonstrate the small likelihood of a false-positive immunoassay test result for cannabinoids, benzodiazepines, or barbiturates after the acute or chronic ingestion of ibuprofen, or after the chronic ingestion of naproxyn or fenoprofen.

scholarly journals An Evaluation of Six Methods for the Detection of Drugs of Abuse in Urine

1989 ◽  
Vol 26 (2) ◽  
pp. 172-181 ◽  
Author(s):  
D Simpson ◽  
D R Jarvie ◽  
R Heyworth
Keyword(s):  
Reliable Method ◽  
Drugs Of Abuse ◽  
Capillary Gc ◽  
Preliminary Screening ◽  
Screening Procedures ◽  
Dual Column ◽  
Positive Results ◽  
Urine Specimens

The detection of drugs of abuse in urine by four commercial immunoassay systems (TDx, BCL and PFI-20 opiates, and PFI-20 morphine) and one commercial TLC system (Toxi-Lab) was investigated and results compared with those obtained by a dual-column capillary GC system. The TDx system was the most reliable method for preliminary screening of urines for opiates; all the commercial immunoassay systems gave some results which were at variance with those of the GC. The GC method proved to be more reliable than the commercial TLC system in discriminating between the different opiates and is recommended for identification of drugs of abuse in urine specimens in which positive results have been obtained with preliminary screening procedures.

Interference of common household chemicals in immunoassay methods for drugs of abuse.

1989 ◽  
Vol 35 (4) ◽  
pp. 648-651 ◽  
Author(s):  
A Warner
Keyword(s):  
Sodium Chloride ◽  
Sodium Bicarbonate ◽  
False Positive ◽  
Fluorescence Polarization ◽  
Drugs Of Abuse ◽  
Low Ph ◽  
Fluorescence Polarization Immunoassay ◽  
Drug Concentrations ◽  
Household Chemicals ◽  
Positive Results

Abstract I report how some adulterants affect results for drugs of abuse in urine as measured by Roche RIA, Syva emit d.a.u., and Abbott TDx fpia (fluorescence polarization immunoassay) for the following drugs: amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, opiates, and phencyclidine (PCP). Sodium chloride interfered negatively with all of these drugs when assayed by emit and caused a slight decrease in measured benzodiazepine concentration by fpia. Drug concentrations were also decreased by added H2O2 (emit: benzodiazepine), Joy detergent (emit: cannabinoid, benzodiazepines, PCP), NaHCO3 (emit: opiate; fpia: PCP), or NaClO [corrected] (emit, RIA, fpia: amphetamines, opiates, PCP; emit, fpia: cannabinoid; emit: benzodiazepines). False-positive results were caused by H2O2 (fpia: benzodiazepines) and Joy (RIA, fpia: benzodiazepine, cannabinoid; fpia: barbiturate, amphetamine). Sodium bicarbonate causes a suspiciously high pH in the urine, NaClO [corrected] an apparently low pH (using pH paper).

Urinary Tract Infection With Gram-Positive Bacteria Does Not Cause False-Positive Results with the Urine-Based Human Chorionic Gonadotropic Point-of-Care Assay

2020 ◽  
Vol 5 (5) ◽  
pp. 987-992
Author(s):  
Kaitlin F Mitchell ◽  
Carey-Ann D Burnham ◽  
Ann M Gronowski
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
False Positive ◽  
Point Of Care ◽  
Coagulase Negative Staphylococcus ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Positive Results ◽  
Urine Specimens

Abstract Background False-positive results for human chorionic gonadotropic (hCG) on point-of-care (POC) devices can occur for a variety of technical and biological reasons. It has been postulated that urinary tract infection can result in false-positive POC hCG assays, but the cause of this phenomenon remains elusive. Gram-positive bacteria have previously been reported to express an hCG-like molecule. We investigated whether urinary tract infection with Gram-positive bacteria can result in false-positive POC hCG. Methods We utilized remnant clinical urine specimens that had been submitted for culture as part of evaluation for urinary tract infection. Urine specimens with >100,000 colony-forming units per milliliter of Gram-positive bacteria (n = 95) were tested on ICON 20 POC hCG tests (Beckman Coulter). Specimens from adult patients that had been collected for clinical testing in the prior 48 hours were included in the study, and only 1 specimen per patient was included. Results Of 95 patients with Gram-positive urine specimens, 42 (44%) were female, and the median age was 62 years. The most common bacteria identified during clinical urine culture of these patients’ specimens were coagulase-negative Staphylococcus species (36/95, 38%), Enterococcus species (34/95, 36%), and Streptococcus agalactiae (9/95, 9%). Five of 95 (5.3%) urine specimens were positive for POC hCG. Chart review revealed that 3 specimens were from pregnant women and 2 were from patients with cancer diagnoses. Conclusions Urine specimens from patients suspected to have urinary tract infection with Gram-positive organisms did not cause positive results on POC hCG test devices.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Comparison of two rapid tests for the detection of legionellaceae in water: a microbiological-immunological method and a commercial gene-probe testkit

1995 ◽  
Vol 31 (5-6) ◽  
pp. 403-406 ◽  
Author(s):  
E. Frahm ◽  
U. Obst
Keyword(s):  
Monoclonal Antibodies ◽  
Conventional Method ◽  
Standard Method ◽  
False Positive ◽  
Gene Probe ◽  
Immunological Method ◽  
Probe Test ◽  
Rapid Tests ◽  
Positive Results

Two recently developed Legionella detection tests, a microbiological-immunological method based on monoclonal antibodies (carried out as a colony-blot assay) and a commercial gene-probe testkit (the EnvironAmp Legionella Kit), are compared with the standard method. The colony-blot assay is faster than the conventional method; the gene-probe test is much faster still and is the most sensitive, but in consequence is at greater risk of false-positive results.

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