Christophe Renard

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.

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 fenofibrates metabolite with MDMA using this assay was systematically found. CONCLUSION Fenofibrates interference with MDMA immunoassay was confirmed. Fenofibrate being widely prescribed, physicians had to be alerted that this treatment could lead to false-positive results.

Heterophilic antibodies: be carefull!

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.

IgE monoclonal gammopathy: A case report and literature review

Immunoglobulin E (IgE) gammopathy is a rare disorder, accounting for just 0.1% of all patients with multiple myeloma (MM). Herein, we report a case of IgE monoclonal gammopathy without any biological and clinical symptoms, and we review 63 published cases in the literature. Demographic, biological and clinical presentations and features appear to be similar to those of other subtypes of MM, with a median age of diagnosis of 67years. There is a slight excess of male patients, and incidence seems to increase with age. The prevalence of renal failure, anaemia and hypercalcaemia at diagnosis was computed to be at 26%, 44% and 18%, respectively, in patients with MM. According to the literature, IgE MM is more aggressive and associated with poorer survival. Nonetheless, cases that are prolonged have also been described.

Immunoglobulin D and cardiac amyloidosis: development and a case illustration.

Amyloidosis results from extra-cellular deposition of proteins which interfere with tissue function. We report the case of a patient with pathological heart involvement which is caused by immunoglobulin D amyloidosis, and review current data on the amyloidois diagnosis and management.

Diagnosis of α1-antitrypsin deficiency using capillary zone electrophoresis.

*Corresponding author: Carine Garcia Hejl, PERCY Military Medical Treatment Facility, Laboratory of Biochemistry, 101 Avenue Henri Barbusse, 92140 Clamart, France, E-mail: cgbiopercy@yahoo.fr Denis Chianea, Julie Plantamura and Philippe Vest: PERCY Military Medical Treatment Facility, Laboratory of Biochemistry, 101 Avenue Henri Barbusse, 92140 Clamart, France Frederic Riviere: PERCY Military Medical Treatment Facility Hospital, Pneumology Clinic, Clamart, France Joshua Sill: Eastern Virginia Medical School, Department of Internal Medicine, Pulmonary/Critical Care Division, Norfolk, VA, USA Isabelle Cuvelier: CERBA Laboratory, Cergy Pontoise, France Christophe Renard: Val de Grâce Military Medical Treatment Facility, Laboratory of Biology, Paris, France Letter to the Editor

Cooperations between biology laboratories of the establishments of healthcare

In France, the cooperations between biological laboratories of the healthcare establishments increased after those realized in the private laboratories. The biologists are confronted with various hypotheses of organization. They are often complex because they may preserve the quality of the care and their continuity while realizing financial economies. These economies are mostly based on the global reduction in the staff and in the equipments by mutualising the biological tests with varying degrees. We describe the various elements to be taken into account (staff, activities, budget, quality, transport, materials) and propose many scenarios of cooperations, from a unique central shape to the transfer of very specialized tests, with their advantages and their inconveniences. The management of human aspects in these cooperations is determining to facilitate their success as well as a reliable preliminary inventory of fixtures.

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

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).

Intérêt de la surveillance biologique d’un patient présentant un coup de chaleur d’exercice

Nous rapportons ici l’observation d’un jeune militaire de 27 ans victime d’un coup de chaleur d’exercice. L’etat clinique du patient est reste stable et non inquietant tout au long de la prise en charge. Cependant, les perturbations du bilan biologique, en particulier de la fonction hepatique et de l’hemostase, mettent en evidence une fois de plus que si le coup de chaleur d’exercice est une pathologie a l’issue le plus souvent favorable dans le cadre d’une prise en charge rapide et adaptee, le syndrome de defaillance multiviscerale qui peut en resulter en fait un accident qui doit mobiliser toute l’attention du clinicien et du biologiste.