Definition of icteric interference index for six biochemical analytes.

Introduction: Icterus, if not detected, can affect the validity of results delivered by clinical laboratories, leading to erroneous results. This study aims to define bilirubin interference for some biochemical analytes and compare it with the manufacturer's data. Material and methods: Serum pools prepared with outpatients' samples were spiked with increasing bilirubin concentration (Merck, reference14370, Darmstadt, Germany) up to 513 µmol/L in order to evaluate the bias for the following biochemical analytes: creatinine (CREA), creatine kinase (CK), cholesterol (CHOL), gamma-glutamyltransferase (GGT), high-density lipoprotein cholesterol (HDL), and total protein (TP). For each analyte, six pools of different concentrations were prepared. Measurements were made employing Cobas 8000 analyser c702-502, Roche Diagnostics (Mannheim, Germany). This study employed a study procedure defined by the Spanish Society of Laboratory Medicine. Results: Obtained bilirubin concentrations producing a negative interference were 103 µmol/L for CHOL, 205 µmol/L for TP and 410 µmol/L for CK, but only for CK values less than 100 U/L. Bilirubin concentrations lower than 513 µmol/L do not produce interference for HDL and GGT. Finally, for the studied bilirubin concentrations, there is no interference for CREA higher than 80 µmol/L. Conclusion: Icterus interferences have been defined for each analyte, observing differences compared to data provided by the manufacturer. The evidence indicates that each laboratory should evaluate icteric interferences to ensure the high quality of the delivered results, thus benefiting patient care.

Elimination of lipaemic interference by high-speed centrifugation.

Introduction: In order to deliver high quality results, detection and elimination of possible analytical interferences, such as lipaemia, is crucial. The aim of this study is to evaluate the efficacy of high-speed centrifugation in eliminating lipaemic interference and to define own lipaemic index (LI) for the studied biochemical analytes. Materials and methods: Evaluated analytes were: albumin, alkaline phosphatase, alanine-aminotransferase (ALT), aspartate-aminotransferase (AST), calcium, creatinine, gamma-glutamyltransferase (GGT), glucose, phosphates, total proteins, urea and total bilirubin. Those analytes and LIs have been analysed in duplicate in the Roche Diagnostics-c8000 analyser in samples centrifuged at 3000 rpm/10 minutes in the SL16 (Thermo Scientific, Waltham, USA) centrifuge and according to an own high-speed centrifugation protocol (12,900 rpm/15 minutes) in the MicroCL17R (Thermo Scientific, Waltham, USA) centrifuge. Lipaemia has been measured in each sample. The efficiency of high-speed centrifugation is verified by the Wilcoxon test (P < 0.05). In cases where significant differences are observed, our own LI is calculated. For ALT and AST, it is verified by McNemar test (P < 0.05). For creatinine, both Wilcoxon and McNemar test were applied. Results: There were statistically significant differences in analyte concentration before and after high-speed centrifugation for: albumin, creatinine, GGT, glucose, phosphates, urea and total bilirrubin. Own LI is calculated. McNemar test shows statistically significant diferences in the proportion of delivered results before and after high-speed centrifugation in ALT, AST and creatinine. Conclusions: This study confirms the efficacy of high-speed centrifugation protocol for all the considered analytes, excepting calcium, alkaline phosphatase and total proteins.

Impact of SARS-CoV-2 infection on liver disease.

Introduction: Abnormal liver biochemistry is not a rare finding in the context of SARS-CoV-2 infection, regardless of patients having pre-existing chronic disease or not. Content: This review examines the current body of knowledge on the relationship between COVID-19 and liver injury, which is frequently found in this setting. Summary: Although the pathogenesis of liver injury is not fully understood, it has been suggested to be the result of a combination of multiple factors. These include direct injury caused by the virus, immune system hyperactivation, ischemic and drug-induced injury. The prognostic valor of these alterations is also the subject of intense research. Due to their potential impact, these alterations require proper management and treatment, especially in patients with chronic liver disease or liver transplant recipients. Outlook: Some aspects associated with liver injury during COVID-19, especially in severe presentations, are not well understood. Studies assessing the clinical impact of COVID-19 on the healthy or diseased liver may help adjust treatment and immunization guidelines to the profile of the patient.

Control of occult hepatitis B virus infection.

Background: The diagnosis of hepatitis B virus (HBV) infection requires HBV DNA testing and serologic testing for detection of the surface antigen (HBsAg) and the hepatitis B core antibody (anti-HBc). There is a population of patients with occult HBV infection (OBI), which is not detected by HBsAg or HBV DNA quantification in blood, despite the presence of active replication in the liver. Scope: This document provides a definition of OBI and describes the diagnostic techniques currently used. It also addresses the detection of patients with risk factors and the need for screening for OBI in these patients. Summary: Correct diagnosis of OBI prevents HBV reactivation and transmission. Diagnosis of OBI is based on the detection of HBV DNA in patients with undetectable HBsAg in blood. Perspectives: A high number of patients with OBI may remain undiagnosed; therefore, screening for OBI in patients with factor risks is essential. For a correct diagnosis of OBI, it is necessary that new markers such as ultrasensitive HBsAg are incorporated, and a more comprehensive marker study is performed by including markers such as cccDNA.

Description of interference in the measurement of troponin T by a high-sensitivity method.

INTRODUCTION: Measurement of high-sensitivity troponin T (hs-TnT) has become an essential step in the diagnosis of acute myocardial infarction. This high-sensitivity method allows quantifying the concentration of troponin T in blood of healthy subjects with a lower inaccuracy compared to previous reagent generations. However, the presence of certain compounds in the sample may interfere with the result. We present a patient who had repeatedly high concentrations of hs-TnT in the serum sample that did not agreed with the signs and symptoms. In addition, ultrasensitive troponin I concentration was undetectable. MATERIALS AND METHODS: To investigate the presence of an interfering compound, different analysis were carried out. In order to discard macro complexes in the sample, the serum was precipitated with polyethylene glycol. In addition, the serum was incubated with Scantibodies Heterophilic Blocking Tube, which can block heterophilic antibodies. Finally, a size exclusion chromatography of the sample was performed by the manufacturer. WHAT HAPPENED: The interfering substance was allocated into fractions with proteins of 150kDa, corresponding to high molecular weight proteins like immunoglobulin G (IgG). This compound was responsible for the falsely elevated hs-TnT results and it affected only the high-sensitivity methods. MAIN LESSON: The detected interfering compound was probably an IgG. This type of interference must be kept in mind in front of discordant results, even if they are extremely rare. Therefore, interdisciplinary cooperation between clinicians, laboratory and manufacturer is essential.

Estudio de correlación entre la concentración de antígeno de superficie y la carga viral del virus de la hepatitis B en una población negativa para el antígeno e / Correlation between hepatitis B surface antigen serum levels and viral load in an hepatitis B e antigen negative population

Introducción. La posible falta de correlación entre la concentración de HbsAg del virus de la hepatitis B y la carga viral observada en nuestro hospital, y la gran controversia existente en torno a este aspecto, ha motivado el presente estudio. Adicionalmente, se realizan estudios de eficiencia diagnóstica de la cuantificación de HbsAg para verificar la utilidad real de la introducción de esta determinación en nuestro laboratorio. Métodos. Se han usado 150 muestras de portadores crónicos del virus. Los individuos HbeAg negativos se dividen en 4 grupos: (HbsAg < 1.000 UI/mL [subgrupo 1], HbsAg > 1.000 UI/mL [subgrupo 2], DNA < 2.000 UI/mL [subgrupo 3], DNA > 2.000 UI/mL [subgrupo 4]). Tanto la cuantificación de HbsAg como la determinación cualitativa de HbeAg se han realizado mediante inmunoanálisis quimioluminiscente en el analizador Architect® i2000SR (Abbott Laboratories, Sligo, Irlanda). La carga viral se ha cuantificado mediante PCR a tiempo real (RT-PCR) (Cobas Ampliprep/Cobas TaqMan® de Roche Diagnostics) (Manheim, Alemania). Los estudios de correlación se han realizado mediante la prueba de Spearman utilizando el programa estadístico MedCalc®. Resultados. Los coeficientes de correlación obtenidos han sido: grupo total HbeAg negativo (r=0,322; p=0,0002); subgrupo 1 (r=0,501; p=0,0001); subgrupo 2 (r=-0,105; p=0,362); subgrupo 3 (r=0,275; p=0,0052); subgrupo 4 (r=0,299; p=0,092). Conclusión. Se ha observado una modesta pero significante correlación entre las concentraciones séricas de HbsAg y los valores de DNA-VHB en individuos HbeAg negativos (AU)

Background. Possible lack of correlation observed among serum hepatitis B surface antigen (HbsAg) concentration results and viral load in our hospital, and the great controversy surrounding this aspect in the literature, has motivated this study. Additionally, diagnostic efficiency analysis of quantitative HbsAg measurement are done in order to verify the real usefulness of the introduction of this test in our laboratory. Methods. 150 hepatitis B chronic carriers samples have been used. Negative HbeAg individuals were divided in four groups (HbsAg < 1,000 UI/mL [subgroup 1], HbsAg > 1,000 UI/mL [subgroup 2], DNA < 2,000 UI/mL [subgroup 3], DNA > 2,000 UI/mL [subgroup 4]). Both quantitative HbsAg and qualitative HbeAg have been performed by a chemiluminiscent immunoassay from Architect® i2000SR analyzer (Abbott Laboratories, Sligo, Ireland). Viral load has been quantified by real time polymerase chain reaction (RT-PCR) (Cobas Ampliprep/Cobas TaqMan® from Roche Diagnostics) (Manheim, Germany). Correlation studies have been performed by the Spearman test. Statistical analysis have been performed using MedCalc® software. Results. Correlation coeficients obtained in this study have been: Total negative HbeAg group (r=0.322; p=.0002); subgroup 1 (r=0.501; p=.0001); subgroup 2 (r=-0.105; p=.362); subgroup 3 (r=0.275; p=.0052); subgroup 4 (r=0.299; p=.092). Conclusion. Modest but significant correlation between HbsAg levels and VHB-DNA values in negative HbeAg individuals has been observed (AU)