Freelite and Kloneus assays in free light chain measurements in patients with renal impairment.

BACKGROUND: Serum free light chain (FLC) quantification is a diagnostic criterion for monoclonal gammopathy and its values in patients with renal impairment are different from those in healthy subjects. The aim of this study was to evaluate Freelite and Kloneus assays in these patients. METHODS: In this retrospective study, serum samples from 226 patients with chronic kidney disease (CKD) of stages 2-5 were measured with a Freelite assay on the Optilite system and with a Kloneus assay on the AU5800 system and compared with controls without renal impairment. RESULTS: Both kappa FLC (K-FLC) and lambda FLC (L-FLC) concentrations increased with Kloneus and Freelite assays with each increment in CKD stage. In patients with CKD, Kloneus detected lower concentrations of K-FLC (median: 20.4 mg/L; 95% range: 9.8-57.2) than Freelite (median: 36.5 mg/L; 95% range: 16.5-137.7) and higher concentrations of L-FLC (median: 32.2 mg/L; 95% range: 14.4-96.7) than Freelite (median: 25.4 mg/L; 95% range: 11.9-86.0). This resulted in significantly different kappa/lambda ratios (K/L-FLC) in patients with CKD for the two tests. The Freelite K/L-FLC in the CKD group (median: 1.50; min-max: 0.66-3.45) was significantly increased compared with healthy controls, and the Kloneus K/L-FLC in the CKD group (median: 0.63; 95 % min-max: 0.34-1.01) was slightly lower. CONCLUSIONS: These findings demonstrate that Freelite and Kloneus assays provide higher but not parallel values when FLCs are measured in patients with CKD, so an increase in K/L-FLC was observed in the case of Freelite, and we found a slight decrease in the case of Kloneus.

Serum free light chain reference intervals in an Optilite and their influence on clinical guidelines.

BACKGROUND: Serum free light chain (FLC) analysis has been incorporated into the International Myeloma Working Group guidelines for the diagnosis and management of all monoclonal gammopathies. These recommendations were solely based on a single assay method (Freelite assay) and instrument. Here, we establish new reference intervals (RIs) for kappa and lambda FLC and the kappa-lambda difference and sum and a new diagnostic range for kappa/lambda FLC ratio (K/L-FLC) in an Optilite turbidimeter (The Binding Site) with the Freelite assay. METHODS: To establish new RIs, the CLSI EP28-A3C protocol was applied to 249 sample blood donors from Fuenlabrada, Spain, and the central 95% and total range were estimated. Samples from patients with polyclonal hypo- and hypergammaglobulinemia were used for the evaluation of K/L-FLC as a monoclonal proliferation index. RESULTS: The new RIs and the new K/L-FLC diagnostic range for the Optilite (0.65-2.56 mg/L) are very different from those in on the guidelines (0.26-1.65 mg/L). We propose new RIs for the K - L difference and the K + L sum. Diagnostic range validation as a monoclonal proliferation index with samples with hypo- and hypergammaglobulinemia confirms this new range. CONCLUSIONS: In this study, we present the FLC RI for Freelite reagents measured on an Optilite turbidimeter. These ranges are different from those provided by the manufacturer and from those used in most studies in the literature, which may lead to patient misclassification. Manufacturers and clinical laboratories must strive to provide RIs for the technology they are using and for their population.

Impact of SARS-CoV-2 pandemic among health care workers in a secondary teaching hospital in Spain.

BACKGROUND: The COVID-19 pandemic has posed a huge challenge to healthcare systems and their personnel worldwide. The study of the impact of SARS-CoV-2 infection among healthcare workers (HCW), through prevalence studies, will let us know viral expansion, individuals at most risk and the most exposed areas in healthcare organizations. The aim of this study is to gauge the impact of SARS-CoV-2 pandemic in our hospital workforce and identify groups and areas at increased risk. METHODS AND FINDINGS: This is a cross-sectional and incidence study carried out on healthcare workers based on molecular and serological diagnosis of SARS-CoV-2 infection. Of the 3013 HCW invited to participate, 2439 (80.9%) were recruited, including 674 (22.4%) who had previously consulted at the Occupational Health Service (OHS) for confirmed exposure and/or presenting symptoms suggestive of COVID-19. A total of 411 (16.9%) and 264 (10.8%) healthcare workers were SARS-CoV-2 IgG and rRT-PCR positive, respectively. The cumulative prevalence considering all studies (IgG positive HCW and/or rRT-PCR positive detection) was 485 (19.9%). SARS-CoV-2 IgG-positive patients in whom the virus was not detected were 221 (9.1%); up to 151 of them (68.3%) did not report any compatible symptoms nor consult at the OHS for this reason. Men became more infected than women (25% vs 18.5%, p = 0.0009), including when data were also classified by age. COVID-19 cumulative prevalence among the HCW assigned to medical departments was higher (25.2%) than others, as well as among medical staff (25.4%) compared with other professional categories (p<0.01). CONCLUSIONS: The global impact of the COVID-19 pandemic on HCW of our centre has been 19.9%. Doctors and medical services personnel have had the highest prevalence of SARS-CoV-2 infection, but many of them have not presented compatible symptoms. This emphasizes the performance of continuous surveillance methods of the most exposed health personnel and not only based on the appearance of symptoms.

Hipotiroidismo consuntivo en paciente con hipotiroidismo primario previo / Consumptive hypothyroidism in patient with previous primary hypothyroidism

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Influencia del informe de laboratorio en el diagnóstico de la disfunción tiroidea en la gestante: más allá del asterisco / The influence of the laboratory report on the diagnosis of thyroid dysfunction in pregnant women: beyond the asterisk

Introducción: La fisiología tiroidea sufre cambios adaptativos durante la gestación, haciendo necesario conocer los límites de normalidad de las hormonas tiroideas según la edad gestacional para una correcta interpretación, principalmente en la enfermedad tiroidea subclínica. Los sistemas de información de laboratorio (SIL) encuentran dificultades para informar rangos de referencia ante diferentes situaciones fisiopatológicas. La labor del facultativo del laboratorio es importante para desarrollar y diseñar herramientas que permitan identificar estas situaciones e interpretar los resultados de forma adecuada. Objetivo: Analizar si el cambio del SIL en nuestro servicio y la emisión del informe del laboratorio con la interpretación de los resultados, habían tenido repercusión sobre la identificación y el seguimiento de la disfunción tiroidea en las gestantes de nuestra área. Material y métodos: Se ha realizado un estudio retrospectivo transversal analizando los resultados de las analíticas de todas las gestantes de primer trimestre y a las que se les habían solicitado pruebas tiroideas en los siguientes 6 meses. Se realizaron 2 grupos, antes y después del cambio de SIL. Resultados: Los porcentajes de seguimiento fueron similares en los 2 grupos, excepto cuando la TSH era patológica para gestantes y normal para población general, es decir, cuando no salía asterisco. Conclusiones: Los rangos de referencia establecidos para población normal no identifican la enfermedad tiroidea subclínica en gestantes. Es imprescindible la intervención activa del facultativo del laboratorio en la valoración de estos resultados. En nuestro estudio un 50% más de las gestantes con hipotiroidismo subclínico se benefició de la estrategia que habíamos introducido

Introduction: Thyroid physiology undergoes adaptive changes during pregnancy, making it necessary to know the reference ranges of thyroid hormones according to gestational age for a correct interpretation, especially in subclinical thyroid disease. Laboratory information systems (LIS) have difficulty in reporting reference ranges (RR) in different pathophysiological situations. The work of the laboratory physician is important in developing and designing tools to identify these situations, and to make an appropriate interpretation of the results. Objective: To determine whether the change in the LIS in our department and the issue of the laboratory report with the interpretation of the results, had an impact on the identification and monitoring of thyroid dysfunction in pregnant women in our area. Material and methods: A retrospective cross-sectional study was carried out by analysing the results of all first-trimester pregnant women and those on whom thyroid tests had been requested in the following six months. The pregnant women were divided into two groups, before and after the change of the LIS. Results: Follow-up percentages were similar in the two groups, except when TSH was abnormal for pregnant women and normal for the general population, that is, when there was no asterisk. Conclusions: The RRs established for the normal population do not identify sub-clinical thyroid disease in pregnant women. The active intervention of the laboratory physician is essential in the evaluation of these results. In our study, more than 50% of the pregnant women with sub-clinical hypothyroidism benefited from the strategy introduced

Recomendación del uso de ecuaciones de corrección de valores de potasio en presencia de interferencia por hemólisis / Recommendation on the use of correction equations for potassium levels in haemolysed samples

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Análisis de todos los pacientes con más de un resultado para autoanticuerpos contra antígenos extraíbles del núcleo en 3 años para establecer un criterio de intervalo de repetición de la prueba / Analysis of all patients with more than one autoantibody against extractable nuclear antigens over a three year period in order to establish a time interval for repeating the test

Introducción. La presencia de anticuerpos anti-ENA precede con frecuencia al inicio de la enfermedad y al establecimiento de un diagnóstico, lo que conlleva la solicitud reiterada del perfil autoinmune. Los patrones de ENA a menudo no se modifican, por lo que su repetición no proporciona información clínica relevante y genera un consumo inefectivo. Nuestro objetivo fue establecer un intervalo mínimo de repetición por debajo del cual la repetición del estudio no sería procedente. Material y métodos. Estudio retrospectivo de todas las muestras con resultado para ENA comprendidas entre diciembre de 2005 y diciembre de 2008. Se incluyeron en el estudio todos los pacientes con más de un resultado. Todos ellos fueron remitidos desde atención especializada. Se analizó para cada paciente el cambio en el perfil de ENA y se calculó la probabilidad de cambio del patrón en un intervalo de tiempo mediante un análisis de supervivencia de Kaplan y Meier. Resultados. No habrá cambio en el patrón de ENA con una probabilidad del 75% en un intervalo de 10 meses, con un 80% en 8 meses, con un 85% en 6 meses, con un 91% en 4 meses y con un 96% en 2 meses. Conclusiones. El tiempo mínimo para la reevaluación del perfil de ENA no debe ser inferior a 82 d (probabilidad de cambio del patrón de ENA del 5%) en ausencia de otros datos clínicos que lo sugieran. Cada centro debería fijar un intervalo de tiempo mínimo de repetición entre 2 y 10 meses (probabilidades de cambio del patrón de ENA entre el 4 y el 25%)(AU)

Introduction. The presence of anti-ENA antibodies often precedes the onset of disease and the establishment of a diagnosis. This leads to a repeat request of the autoimmune profile of the patient. ENA patterns often do not change and their repetition does not provide relevant clinical information and leads to ineffective testing. Our objective was to establish a minimum time below which the repetition of anti-ENA patterns would not be appropriate. Material and methods. A retrospective study was conducted on all the samples with an ENA result between December 2005 and December 2008. The study included all patients with more than one result. All of them were referred from specialist care. The change in the profile of ENA was studied in each patient, and the probability of change in the ENA pattern over a time interval was calculated using the Kaplan and Meier analysis of survival. Results. The results showed a probability of 75% that there would be no change with 10 months as a minimum time to repetition, 80% with 8 months, 85% with 6 months, 91% with 4 months, and 96% with 2 months. Conclusions. The minimum time to repeat the ENA study should not be less than 82 days (5% probability of a changing ENA pattern) in the absence of new clinical symptoms. Each center should set an interval of repetition between 2 and 10 months (4% and 25% probability of changing ENA pattern, respectively)(AU)