Modelo de coparticipación de los facultativos en la gestión clínica eficiente de las pruebas subcontratadas / Multidisciplinary model in the efficient clinical management of requested tests

Introducción. El uso del laboratorio es inadecuado (excesivo o innecesario) y es preciso controlarlo. Material y métodos. Elaborar una estrategia para gestionar, según criterios de medicina basada en la evidencia, la derivación de pruebas subcontratadas y comparar los resultados entre dos años consecutivos. Resultados. La demanda se ha reducido un 6,56% y los costes un 26,9%. Es de destacar que solo el 1,9 % de los peticionarios a los que se les ha denegado alguna prueba contacta con el laboratorio para reclamar o mostrar su disconformidad. Conclusiones. El profesional del laboratorio clínico debe implicarse como consultor clínico para mejorar la eficiencia de las pruebas de laboratorio (AU)

Introduction. The use of the laboratory is inadequate and it is necessary to control it. Materials and methods. To elaborate a strategy to manage, according to evidence-based medicine criteria, the origin of requested tests and to compare the results between two consecutive years. Results. The demand has reduced by 6.56% and the costs by 26.9%. It is worth emphasizing that only 1.9% of the requesters, for which some test has been refused, contacts the laboratory to show disapproval. Conclusions. The professionals of the clinical laboratory must be involved in their function as clinical consultant to improve the efficiency of laboratory tests (AU)

Rheumatoid factor interference in a tacrolimus immunoassay.

Recently, there has been an interest in the use of tacrolimus for the treatment of rheumatoid arthritis (RA). The role of rheumatoid factor (RF) as a cause of immunoassay interferences is well known. This study is the first to investigate the susceptibility of a tacrolimus immunoassay to interference by RF. Tacrolimus apparent concentrations were determined using the antibody conjugated magnetic immunoassay (ACMIA) run on the Dimension RxL Immunoassay System in 100 randomly selected samples previously submitted for routine diagnostic or monitoring of RA in patients not receiving tacrolimus. Fifty of them had an RF concentration exceeding 100 IU/L and 50 had an RF concentration below 20 IU/L. Samples with tacrolimus apparent whole-blood concentrations above 2.3 ng/mL (limit of quantification of the ACMIA assay alleged by the vendor) were considered as potential false positives. No positive tacrolimus result was found among the 50 samples with serum RF < 20 IU/mL. Among the 50 selected samples from patients with RF > 100 IU/mL (RF range 110-2650 IU/mL), 2 were positive for tacrolimus with ACMIA. In both cases, the pretreatment of these samples with an immunoglobulin blocking agent reduced the apparent tacrolimus concentrations to below the limit of detection. This was confirmed using the alternative and reference tacrolimus assays, both of which reported results below their respective limits of detection. The measured human anti-mouse antibodies levels were found to be elevated. These results show that certain patients with positive RF can have false-positive tacrolimus results using the tacrolimus ACMIA-Flex immunoassay on a Dimension RXL analyzer, which was not the case with 2 other techniques. The interference with the tacrolimus ACMIA results was suppressed after preincubation with an immunoglobulin blocking reagent.