[Waldenström's macroglobulinemia with an uncommon presentation]. / Macroglobulinémie de Waldenström: à propos d'une présentation clinicobiologique peu commune.

Waldenström's macroglobulinemia is a rare disease with an indolent clinical course. The median age of the affected patient is 65 years. Nevertheless, we report a case of Waldenström's macroglobulinemia revealed by a splenomegaly and severe pancytopenia, in a 51-year-old man without previous medical history. According to the recent consensus recommendations for the clinicopathological definition of Waldenström's macroglobulinemia, diagnosis was made through morphological and immunophenotypic data of medullary cells. The reduced survival of the patient is associated with the importance of the cytopenia.

[ROC (receiver operating characteristics) curve: principles and application in biology]. / La courbe ROC (receiver operating characteristic): principes et principales applications en biologie clinique.

Laboratory test's diagnostic performances are generally estimated by means of their sensibility, specificity and positive and negative predictive values. Unfortunately, these indices reflect only imperfectly the capacity of a test to correctly classify subjects into clinically relevant subgroups. The appeal to ROC (receiver operating characteristic) curve appears as a tool of choice for this evaluation. Used in the medical domain since the 60s, ROC curve is a graphic representation of the relation existing between the sensibility and the specificity of a test, calculated for all possible cut-off. It allows the determination and the comparison of the diagnostic performances of several tests. It is also used to consider the optimal cut-off of a test, by taking into account epidemiological and medical - economic data of the disease. Used in numerous medical domains, this statistical tool is easily accessible thanks to the development of computer softwares. This article exposes the principles of construction and exploitation of a ROC curve.

[Contribution of the laboratory to the evaluation of brain-dead patients for obtaining organs from dead individuals]. / Apport du laboratoire dans l'évaluation des patients en mort encéphalique en vue d'un prélèvement d'organes sur la personne décédée.

The removal organ in order to transplantation is realized often for patient deceased. It was regulation activity that passes in urgency context where laboratory play an important role. The biochemistry, immunology, haematology, toxicology and microbiology analysis allows the validation of the donors, the supervision of the functional quality of organ and the definition of the best couple donor-recipient.

[Direct determination or estimated value of plasma ionized calcium : indications and limits]. / Dosage direct du calcium ionisé plasmatique ou estimation par calcul: intérêts et limites.

Calcium plays a fundamental role in many essential for life functions. Ionized calcium (Ca(++) ) represents free fraction and 50% of the total calcium in the plasma is accepted as its physiologically active form. On almost all laboratories, only total calcium is routinely measured, and ionized calcium concentration is calculated based on calcium, protein or albumin concentrations for many plasma sample or with others parameters like pH. Since 1935, the literature was abounted with "correction" formulae of varying degree of sophistication. Many laboratories routinely use correction formulae to either calculate an "adjusted" or "corrected" total calcium, or "ionized" fraction is calculated,but these determinations lack of accuracy or precision. Errors associated with the measurement of the other variables contribuate to the difficulty in producing a useful correction formulae. Direct measurement of ionized calcium by potentiometry is the method of choice for this assay. Improvements in ion selective electrodes (ISE) technology make possible the routine clinical measurement of Ca(++). However this technology implies several obligations for its use, particulary in blood ampling, storage and transport. In this review, characteristics of different available analysers are described. We think that Ca(++) should be systematically performed and not calculated in pathological situations where an possible alteration of the calcium metabolism is found especially in multiple myeloma in which paraprotein may bind calcium.

[Drug interference with the determination of urinary proteins with pyrocatechol violet Upro Vitros slides]. / Interférences médicamenteuses sur le dosage des protéines urinaires avec les plaques Upro Vitros au violet de pyrocatéchol.

The purpose of this study is to investigate drug's interference on proteinuria's determination with pyorcatechol violet (Vitros technology). Five drugs were selected: gelatin based vascular replacement fluids (Plasmion), deferoxamine (Desféral), ceftriaxone (Rocéphine), ceftazidime (Fortum) and imipeneme (Tienam). To state precisely the role played by slide's technology, a liquid phase dosage was simultaneously made with pyrocatechol violet. No interference was notified with therapeutical range for four of them: gelatin, deferoxamine, ceftazidime and imipeneme. Slides technology prevents from gelatin's interference because the colorant is sensible to this drugs. On the other hand, positive interference was observed with ceftriaxone for urinary concentration upper than 0.75 g/L. This concentration is lower than that notified by Vitros laboratory in the technical data.