A Cross-Reactivity of Fenofibric Acid With MDMA DRI Assay.

BACKGROUND: Within the framework of routine fitness examinations, French Air Force military crew underwent urine testing for 3,4 methylenedioxymetamphetamine (MDMA [ecstasy]). The cross-reactivity of a dyslipidemic drug, fenofibrate, with an MDMA immunoassay was studied and confirmed on a large population sample. METHODS: A 3-year retrospective study was performed on the MDMA DRI Ecstasy Assay on the Unicel DXC 600. In the event of positive test result, a confirmatory testing was carried out by gas chromatography/mass spectrometry (GC/MS) to establish the presence of MDMA. When analysis by GC/MS did not confirm the presence of MDMA, a false-positive result was suspected and the samples were analyzed by high-performance liquid chromatography-mass spectrometry to identify a potential interfering substance. RESULTS: A total of 15,169 urine samples, from 7,803 patients, were tested for 3 years. Of the tested samples, 22 (0.15%) were positive by DRI Ecstasy Assay. None of them were positive by GC/MS. A cross-reactivity of fenofibrate's metabolite with MDMA using this assay was systematically found. CONCLUSION: Fenofibrate's interference with MDMA immunoassay was confirmed. Fenofibrate being widely prescribed, physicians had to be alerted that this treatment could lead to false-positive results.

Working towards accreditation by the International Standards Organization 15189 Standard: how to validate an in-house developed method an example of lead determination in whole blood by electrothermal atomic absorption spectrometry.

Laboratories working towards accreditation by the International Standards Organization (ISO) 15189 standard are required to demonstrate the validity of their analytical methods. The different guidelines set by various accreditation organizations make it difficult to provide objective evidence that an in-house method is fit for the intended purpose. Besides, the required performance characteristics tests and acceptance criteria are not always detailed. The laboratory must choose the most suitable validation protocol and set the acceptance criteria. Therefore, we propose a validation protocol to evaluate the performance of an in-house method. As an example, we validated the process for the detection and quantification of lead in whole blood by electrothermal absorption spectrometry. The fundamental parameters tested were, selectivity, calibration model, precision, accuracy (and uncertainty of measurement), contamination, stability of the sample, reference interval, and analytical interference. We have developed a protocol that has been applied successfully to quantify lead in whole blood by electrothermal atomic absorption spectrometry (ETAAS). In particular, our method is selective, linear, accurate, and precise, making it suitable for use in routine diagnostics.

[Internal audit in medical laboratory: what means of control for an effective audit process?]. / Audit interne dans un laboratoire de biologie médicale: quels moyens de maîtrise pour un processus d'audit efficace ?

To prepare the French Accreditation Committee (COFRAC) visit for initial certification of our medical laboratory, our direction evaluated its quality management system (QMS) and all its technical activities. This evaluation was performed owing an internal audit. This audit was outsourced. Auditors had an expertise in audit, a whole knowledge of biological standards and were independent. Several nonconformities were identified at that time, including a lack of control of several steps of the internal audit process. Hence, necessary corrective actions were taken in order to meet the requirements of standards, in particular, the formalization of all stages, from the audit program, to the implementation, review and follow-up of the corrective actions taken, and also the implementation of the resources needed to carry out audits in a pre-established timing. To ensure an optimum control of each step, the main concepts of risk management were applied: process approach, root cause analysis, effects and criticality analysis (FMECA). After a critical analysis of our practices, this methodology allowed us to define our "internal audit" process, then to formalize it and to follow it up, with a whole documentary system.

[Heterophilic antibodies: be carefull!]. / Anticorps hétérophiles: restez vigilants !

The determination of plasma level of cardiac troponin I or T is recommended by the French Health Authority to diagnose myocardial infarction. However false positive results associated with the presence of heterophilic antibodies are described in the literature. This interference can lead to unnecessary invasive procedures, sometimes even dangerous. We report the case of a patient with falsely elevated troponin Ic concentration due to these antibodies. This case is characterized by the intensity of the abnormalities, the diversity of biological parameters affected and the discrepancies between biology and clinic. This case report confirms that modern immunoassays are always affected by heterophilic antibodies. We present here an example of such interference.

[Systemic amyloidosis revealed by an intense nephrotic syndrome]. / À propos d'une amylose révélée par un syndrome néphrotique intense.

We report the case of a patient with steroid-resistant nephrotic syndrome which is caused by a renal amyloidosis. This clinical case is characterized by intensity of clinicals and biologicals abnormalities and by its uncommun cause. We also review current data on the nephrotic syndrome as well as on the systemic amyloidosis and to evoke the indications of the immunoglobulin free-light-chains quantification in the diagnostic approach.

[Validation of plasma creatinine measurement on UniCel DxC 600 according to LAB GTA 04 recommendation]. / Vérification initiale d'une nouvelle méthode de dosage de la créatinine plasmatique sur UniCel (R) DxC 600 selon les recommandations du LAB GTA 04.

The accreditation process, according to NF EN ISO 15189, implies a prior evaluation of the new reagent on-site for the implementation of each new assay technique. Thus, our new standardized method for determination of creatinine (non compensated method) in plasma or serum on UniCel DxC 600 (Beckman Coulter) has been tested according to LAB GTA 04 protocol. The reagent meets the quality criteria recommended by Valtec protocol, except fidelity with the low concentration standard (50 micromol/L). Besides there is no problem of results transferability with the two other techniques used in the laboratory (Jaffe compensated and enzymatic methods performed on Cobas Integra 800).