False-negative results in the immunoassay analysis of drugs of abuse: can adulterants be detected by sample check test?

Background The dilution or adulteration of urine is a serious problem in drugs of abuse testing. Tests to identify adulteration are currently available. This study investigated the ability of the CEDIA® sample check to detect adulteration. Methods Eight different drugs of abuse were added to a urine sample obtained from a healthy, drug-free subject: 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), 3,4-methylenedioxyamphetamine, benzoylecgonine, D-amphetamine sulphate, ethyl-D-glucuronide, morphine sulphate, oxazepam, (-)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol. Urine samples were diluted to yield three samples of drugs of abuse concentrations close to general cut-offs as used in methadone treatment centres, by health authorities for psychological tests and in traffic medicine. Aspirin, citric acid, CrO3, H2O2, soap, sodium metaborate, vitamin C were added in three, HCl and NaOH in one, and NaN3 in two concentrations. All samples were measured with commercially available immunological assays shortly after sample preparation and 24 h later. All samples were further analysed with the CEDIA® sample check reaction which may identify adulteration. Results Oxidizing reagents (H2O2 or CrO3) are most effective in interfering in the measurement of benzoylecgonine, EDDP, ethyl-D-glucuronide and morphine sulphate. The measurement of (-)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol is affected by many adulterants. Adulteration with HCl and NaOH was identified with the sample check reaction. NaN3 generated false negative results for a number of drugs of abuse. Conclusions Urine samples with drugs of abuse concentrations above cut-offs can be successfully tampered with adulterants in a way which cannot be detected with the CEDIA® sample check assay.

The Urine Marker Test: An Alternative Approach to Supervised Urine Collection for Doping Control.

BACKGROUND: Urine sample collection for doping control tests is a key component of the World Anti-Doping Agency's fight against doping in sport. However, a substantial number of athletes experience difficulty when having to urinate under supervision. Furthermore, it cannot always be ensured that athletes are actually delivering their own urine. A method that can be used to alleviate the negative impact of a supervised urination procedure and which can also identify urine as coming from a specific athlete is the urine marker test. Monodisperse low molecular weight polyethylene glycols (PEGs) are given orally prior to urination. Urine samples can be traced to the donor by analysis of the PEGs previously given. OBJECTIVE: The objective of this study was to investigate the use of the urine marker during urine doping control testing. METHODS: Two studies investigated athletes' acceptance of this new method via two questionnaires (n = 253). Furthermore, a third study (n = 91) investigated whether ingestion of the marker can identify the urine as coming from a specific person and whether the marker interferes with the detection of prohibited substances. RESULTS AND CONCLUSIONS: The results indicate that this new method finds wide acceptance both from athletes who have only heard about the procedure and those who have actually tested the new method. Furthermore, the marker, which can identify urine as coming from a specific person, does not interfere with the detection of prohibited substances.

Efficacy of a polyethylene glycol marker system in urine drug screening in an opiate substitution program.

AIMS: Screening for concomitant drug consumption is necessary in opiate substitution therapy of opiate-dependent patients. Adulteration of samples is a common problem in this setting. A recently developed polyethylene glycol marker system allows reliable identification of urine samples. In this study, we aimed to compare the rates of drug detection in conventional and marker urine samples. DESIGN: This cross-sectional evaluation was performed in an ambulatory opiate substitution program. We studied 55 opiate-dependent patients (32 men, 23 women). In all patients we compared the rates of drugs detected in the marker urine with the most recent conventional urine control. Additionally we assessed the rate of marker urine manipulation. FINDINGS: In the conventional urine controls, opiates and benzodiazepines were found in 3.6 and 27%, respectively, whereas in the marker urine controls, these rates were 33 and 40%, respectively. Signs of urine manipulation were present in 35%. The rates of concomitant consumption and urine manipulation were higher among the patients without than among those with take-home substitution. CONCLUSIONS: With the marker urine, an unexpectedly high prevalence of concomitant consumption can be found. Marker urine testing has a significantly higher sensitivity for the detection of concomitant drug use.

A multi-center quality control study of different CA15-3 immunoassays.

A long-term multi-center quality control study of CA15-3 determinations based on measurements of liquid BIOREF CA15-3 control sera was conducted in 17 participating laboratories. Seven different CA15-3 assays were applied using the appropriate automatic immunoanalyzers. CA15-3 means were determined for BIOREF low, medium and high level control sera. Values were 19.3 +/- 2.7 kU/l, 75.2 +/- 11.4 kU/l and 162.9 +/- 37.1 kU/l, respectively. Inter-assay imprecisions were calculated for each of the controls for each laboratory and for each of the methods, with coefficients of variation (CV) ranging from 2.9-15.5%. As a means of evaluation of assay linearity concentration ratios (high/medium, medium/low, high/low) were calculated and found to be in good agreement with reference values throughout the study. Individual long-term time courses of CA15-3 control measurements provided evidence for variability of test results due to changes in assay calibration. Comparisons with CV data obtained with BIOREF controls 17 years ago demonstrate significant improvements of CA15-3 assay precision in recent years. In conclusion, test-independent reference material can be used for CA15-3 quality control and in particular enables applicants to check for long-term stability of CA15-3 assay performance.

Urine labeling with orally applied marker substances in drug substitution therapy.

The compliance of 581 drug addicts attending six methadone substitution outpatient clinics was determined over a period of 18 months. Urine from these patients was labeled following oral administration of low molecular weight polyethylene glycols as marker substances. These substances were measured in approx. 5800 urine samples. A protocol for applying marker substances and ways to prevent substitution of urine samples were evaluated. Normal values for marker substances in urine were determined. The results suggest that this labeling procedure is a new diagnostic tool to prevent manipulation of urine samples by drug addicts receiving substitution therapy.

Clinical use of polyethylene glycols as marker substances and determination in urine by liquid chromatography.

Adulteration of samples is a serious problem in the analysis of drugs of abuse. One of the most frequent methods is substitution of urines by "clean" urines to gain false-negative results in laboratory tests for drugs of abuse. One way to approach this problem may be to label the patient's urine with marker substances which are given orally prior to the delivery of urine. This concept is based on methods for determining malabsorption in pediatric medicine. We report a protocol for evaluating low-molecular-mass polyethylene glycols as enteral labelling marker substances. For monitoring renal excretion of the ingested polyethylene glycols we have developed and optimised an isocratic reversed-phase high-performance liquid chromatographic method with automatic sample cleanup by column switching in the back-flush technique and with RI detection. The chromatographic procedure is simple, reliable and rapid, allowing a high sample throughput for routine screening.

Differential expression of beta-galactoside alpha2,6 sialyltransferase and sialoglycans in normal and cirrhotic liver and hepatocellular carcinoma.

SUMMARY: Sialyltransferases sialylate plasma glycoproteins in hepatocytes and may (as hepatic key enzymes) constitute markers for liver diseases. We examined expression of the prevalent alpha2,6 sialyltransferase (ST6Gal I) and sialoglycans in normal liver, cirrhotic liver, and hepatocellular carcinoma (HCC) using a new ST6Gal I-specific mAb and recombinant fusion proteins of CD22 and sialoadhesin recognizing alpha2,6- or alpha2,3-sialylated glycans in immunohistology and flow cytometry. In normal and cirrhotic liver, ST6Gal I and sialoglycans were localized in the Golgi region of hepatocytes surrounding the bile canaliculi and along the bile canaliculi, respectively. Sialoglycans were additionally recognized in Kupffer cells, bile ducts, endothelial cells, and oval cells. Well-differentiated and moderately differentiated HCC showed Golgi and diffuse cytoplasmic staining of ST6Gal I and sialoglycans, whereas the cytoplasmic staining for ST6Gal I and sialoglycans was decreased or even absent in poorly differentiated HCC. Detection of sialoglycans by the recombinant fusion proteins in Western blots of cell lysates derived from cell lines revealed two major double bands of sialoglycoproteins at 65 and 120 kDa for hepatocytes, three major bands at 54, 49, and 44 kDa for colonic epithelial cells, and one band at 60 kDa for endothelial cells. Our results describe the expression patterns of ST6Gal I and sialoglycans in various liver tissues and demonstrate an altered expression of these structures between benign and malignant hepatocellular lesions.