Handling of lipemic samples in the clinical laboratory.

Interferences in the clinical laboratory may lead physicians misinterpret results for some biological analytes. The most common analytical interferences in the clinical laboratory include hemolysis, icterus and lipemia. Lipemia is defined as turbidity in a sample caused by the accumulation of lipoproteins, mainly very-low density lipoproteins (VLDL) and chylomicrons. Several methods are available for the detection of lipemic samples, including the lipemic index, or triglyceride quantification in serum or plasma samples, or mean corpuscular hemoglobin (MCHC) concentration in blood samples. According to the European Directive 98/79/CE, it is the responsibility of clinical laboratories to monitor the presence of interfering substances that may affect the measurement of an analyte. There is an urgent need to standardize interference studies and the way interferences are reported by manufacturers. Several methods are currently available to remove interference from lipemia and enable accurate measurement of biological quantities. The clinical laboratory should establish a protocol for the handling of lipemic samples according to the biological quantity to be tested.

Discrepancies in Lipemia Interference Between Endogenous Lipemic Samples and Smoflipid®-Supplemented Samples.

Background: Manufacturers evaluate lipemia-induced interference using Intralipid®, but it does not contain all lipoprotein types. The aim of this study was to evaluate lipemiainduced interference in biochemical parameters from endogenous lipemic samples and SMOFlipid® supplemented samples, in order to assess if SMOFlipid® can be used in lipemic interference studies. Methods: Serum pools were supplemented with SMOFlipid® to achieve 800 mg/dL and 1500 mg/dL triglyceride concentration, and analyzed for 25 biochemical parameters both before and after the supplementation. In another independent phase, lipemic serum pools were prepared choosing patient samples of 800 mg/dL and 1500 mg/dL triglyceride concentration. These lipemic serum pools were ultracentrifugated in order to remove lipids. Biochemical parameters were analyzed before and after ultracentrifugation. The bias between SMOFlipid®-supplemented samples and endogenous lipemic samples were compared. The bias between the lipemic and non-lipemic samples were compared with the reference change value. Results: At 800 mg/dL triglyceride concentration, we found that total protein and transferrin had been affected only in endogenous lipemic serum samples. Magnesium and creatinine had been affected only in SMOFlipid®-supplemented samples. At 1500 mg/dL triglyceride concentration, we found that total protein, amylase, ferritin and glucose had lipemic interference only in endogenous lipemic samples, and chloride only in SMOFlipid®-supplemented samples. Conclusions: The use of SMOFlipid®-supplemented samples does not provide suitable data to estimate lipemia-induced interference. Thus, interference studies should be performed using a wide variety of lipemic patient samples that represent the heterogeneity of the lipoprotein particles size.

Harmonized D-dimer levels upon admission for prognosis of COVID-19 severity: Results from a Spanish multicenter registry (BIOCOVID-Spain study).

Coagulopathy is a key feature of COVID-19 and D-dimer has been reported as a predictor of severity. However, because D-dimer test results vary considerably among assays, resolving harmonization issues is fundamental to translate findings into clinical practice. In this retrospective multicenter study (BIOCOVID study), we aimed to analyze the value of harmonized D-dimer levels upon admission for the prediction of in-hospital mortality in COVID-19 patients. All-cause in-hospital mortality was defined as endpoint. For harmonization of D-dimer levels, we designed a model based on the transformation of method-specific regression lines to a reference regression line. The ability of D-dimer for prediction of death was explored by receiver operating characteristic curves analysis and the association with the endpoint by Cox regression analysis. Study population included 2663 patients. In-hospital mortality rate was 14.3%. Harmonized D-dimer upon admission yielded an area under the curve of 0.66, with an optimal cut-off value of 0.945 mg/L FEU. Patients with harmonized D-dimer ≥ 0.945 mg/L FEU had a higher mortality rate (22.4% vs. 9.2%; p < 0.001). D-dimer was an independent predictor of in-hospital mortality, with an adjusted hazard ratio of 1.709. This is the first study in which a harmonization approach was performed to assure comparability of D-dimer levels measured by different assays. Elevated D-dimer levels upon admission were associated with a greater risk of in-hospital mortality among COVID-19 patients, but had limited performance as prognostic test.

Blood Rheological Characterization of ß-Thalassemia Trait and Iron Deficiency Anemia Using Front Microrheometry.

The purpose of this work is to develop a hematocrit-independent method for the detection of beta-thalassemia trait (ß-TT) and iron deficiency anemia (IDA), through the rheological characterization of whole blood samples from different donors. The results obtained herein are the basis for the development of a front microrheometry point-of-care device for the diagnosis and clinical follow-up of ß-TT patients suffering hematological diseases and alterations in the morphology of the red blood cell (RBC). The viscosity is calculated as a function of the mean front velocity by detecting the sample fluid-air interface advancing through a microfluidic channel. Different viscosity curves are obtained for healthy donors, ß-TT and IDA samples. A mathematical model is introduced to compare samples of distinct hematocrit, classifying the viscosity curve patterns with respect to the health condition of blood. The viscosity of the fluid at certain shear rate values varies depending on several RBC factors such as shape and size, hemoglobin (Hb) content, membrane rigidity and hematocrit concentration. Blood and plasma from healthy donors are used as reference. To validate their potential clinical value as a diagnostic tool, the viscosity results are compared to those obtained by the gold-standard method for RBC deformability evaluation, the Laser-Optical Rotational Red Cell Analyzer (LoRRCA).

Monocyte distribution width (MDW) performance as an early sepsis indicator in the emergency department: comparison with CRP and procalcitonin in a multicenter international European prospective study.

BACKGROUND: Early sepsis diagnosis has emerged as one of the main challenges in the emergency room. Measurement of sepsis biomarkers is largely used in current practice to improve the diagnosis accuracy. Monocyte distribution width (MDW) is a recent new sepsis biomarker, available as part of the complete blood count with differential. The objective was to evaluate the performance of MDW for the detection of sepsis in the emergency department (ED) and to compare to procalcitonin (PCT) and C-reactive protein (CRP). METHODS: Subjects whose initial evaluation included a complete blood count were enrolled consecutively in 2 EDs in France and Spain and categorized per Sepsis-2 and Sepsis-3 criteria. The performance of MDW for sepsis detection was compared to that of procalcitonin (PCT) and C-reactive protein (CRP). RESULTS: A total of 1,517 patients were analyzed: 837 men and 680 women, mean age 61 ± 19 years, 260 (17.1%) categorized as Sepsis-2 and 144 patients (9.5%) as Sepsis-3. The AUCs [95% confidence interval] for the diagnosis of Sepsis-2 were 0.81 [0.78-0.84] and 0.86 [0.84-0.88] for MDW and MDW combined with WBC, respectively. For Sepsis-3, MDW performance was 0.82 [0.79-0.85]. The performance of MDW combined with WBC for Sepsis-2 in a subgroup of patients with low sepsis pretest probability was 0.90 [0.84-0.95]. The AUC for sepsis detection using MDW combined with WBC was similar to CRP alone (0.85 [0.83-0.87]) and exceeded that of PCT. Combining the biomarkers did not improve the AUC. Compared to normal MDW, abnormal MDW increased the odds of Sepsis-2 by factor of 5.5 [4.2-7.1, 95% CI] and Sepsis-3 by 7.6 [5.1-11.3, 95% CI]. CONCLUSIONS: MDW in combination with WBC has the diagnostic accuracy to detect sepsis, particularly when assessed in patients with lower pretest sepsis probability. We suggest the use of MDW as a systematic screening test, used together with qSOFA score to improve the accuracy of sepsis diagnosis in the emergency department. Trial Registration ClinicalTrials.gov (NCT03588325).

Cardiac troponin and COVID-19 severity: Results from BIOCOVID study.

BACKGROUND: Myocardial injury is a common finding in COVID-19 strongly associated with severity. We analysed the prevalence and prognostic utility of myocardial injury, characterized by elevated cardiac troponin, in a large population of COVID-19 patients, and further evaluated separately the role of troponin T and I. METHODS: This is a multicentre, retrospective observational study enrolling patients with laboratory-confirmed COVID-19 who were hospitalized in 32 Spanish hospitals. Elevated troponin levels were defined as values above the sex-specific 99th percentile upper reference limit, as recommended by international guidelines. Thirty-day mortality was defined as endpoint. RESULTS: A total of 1280 COVID-19 patients were included in this study, of whom 187 (14.6%) died during the hospitalization. Using a nonspecific sex cut-off, elevated troponin levels were found in 344 patients (26.9%), increasing to 384 (30.0%) when a sex-specific cut-off was used. This prevalence was significantly higher (42.9% vs 21.9%; P < .001) in patients in whom troponin T was measured in comparison with troponin I. Sex-specific elevated troponin levels were significantly associated with 30-day mortality, with adjusted odds ratios (ORs) of 3.00 for total population, 3.20 for cardiac troponin T and 3.69 for cardiac troponin I. CONCLUSION: In this multicentre study, myocardial injury was a common finding in COVID-19 patients. Its prevalence increased when a sex-specific cut-off and cardiac troponin T were used. Elevated troponin was an independent predictor of 30-day mortality, irrespective of cardiac troponin assay and cut-offs to detect myocardial injury. Hence, the early measurement of cardiac troponin may be useful for risk stratification in COVID-19.

Predicting pulmonary embolism in patients infected with COVID-19 based on D-dimer levels and days between diagnosis of the infection and D-dimer determination.

Ruling out pulmonary embolism (PE) can be challenging in a situation of elevated D-dimer values such as in a case of COVID-19 infection. Our objective was to evaluate the difference in D-dimer values of subjects infected with COVID-19 in those with PE and those without and to analyze the predictive value of D-dimer for PE in these subjects based on the day of D-dimer determination. This was an observational, retrospective study, conducted at a tertiary hospital. All subjects with PCR-confirmed COVID-19 infection requiring hospital admission at our institution between the months of March and April 2020 were included in the study. We compared D-dimer levels in subjects who went on to develop a PE and those who did not. We then created a model to predict the subsequent development of a PE with the current D-dimer levels of the subject. D-dimer levels changed over time from COVID-19 diagnosis, but were always higher in subjects who went on to develop a PE. Regarding the predictive model created, the area under the curve of the ROC analyses of the cross-validation predictions was 0.72. The risk of pulmonary embolism for the same D-dimer levels varied depending on the number of days elapsed since COVID-19 diagnosis and D-dimer determination. To conclude, D-dimer levels were elevated in subjects with a COVID-19 infection, especially in those with PE. D-dimer levels increased during the first 10 days after the diagnosis of the infection and can be used to predict the risk of PE in COVID-19 subjects.

Characteristics and laboratory findings on admission to the emergency department among 2873 hospitalized patients with COVID-19: the impact of adjusted laboratory tests in multicenter studies. A multicenter study in Spain (BIOCOVID-Spain study).

Identification of predictors for severe disease progression is key for risk stratification in COVID-19 patients. We aimed to describe the main characteristics and identify the early predictors for severe outcomes among hospitalized patients with COVID-19 in Spain. This was an observational, retrospective cohort study (BIOCOVID-Spain study) including COVID-19 patients admitted to 32 Spanish hospitals. Demographics, comorbidities and laboratory tests were collected. Outcome was in-hospital mortality. For analysis, laboratory tests values were previously adjusted to assure the comparability of results among participants. Cox regression was performed to identify predictors. Study population included 2873 hospitalized COVID-19 patients. Nine variables were independent predictors for in-hospital mortality, including creatinine (Hazard ratio [HR]:1.327; 95% Confidence Interval [CI]: 1.040-1.695, p = .023), troponin (HR: 2.150; 95% CI: 1.155-4.001; p = .016), platelet count (HR: 0.994; 95% CI: 0.989-0.998; p = .004) and C-reactive protein (HR: 1.037; 95% CI: 1.006-1.068; p = .019). This is the first multicenter study in which an effort was carried out to adjust the results of laboratory tests measured with different methodologies to guarantee their comparability. We reported a comprehensive information about characteristics in a large cohort of hospitalized COVID-19 patients, focusing on the analytical features. Our findings may help to identify patients early at a higher risk for an adverse outcome.

Performance evaluation of the new hematology analyzer UniCel DxH 900.

INTRODUCTION: UniCel DxH900 (Beckman Coulter, Miami, Florida, USA) is a quantitative, multi-parameter, automated hematology analyzer for in vitro diagnostic use in clinical laboratories. The aim of this study was to evaluate the analytical performance of the new DxH900 analyzer to verify its diagnostic and clinical utility in the hematology laboratory of a tertiary care hospital in Spain. The most important and novel feature offered by DxH900 analyzer is providing MDW (monocyte distribution width), a new hematologic parameter which is being clinically validated as an early sepsis indicator with promising results. METHODS: We evaluated imprecision (including MDW), linearity, and carryover of DxH900. Method comparison for cell blood count (CBC) was performed in relation to DxH800 with 100 samples. We compared leukocyte differential (DIFF) from DxH900 with manual 400-cell differential. 390 samples were assessed for flag performance. RESULTS: Results obtained for between days and within-run imprecision were good. DxH900 showed excellent linearity (R = 1.00) over analytical range for white blood cells, red blood cells, hemoglobin, platelets, and reticulocyte count (RET) (R = 0.96) and no significant carryover effect. CBC and RET on the DxH900 correlated well with DxH800 (R ≥ 0.99). Comparison with manual differential showed excellent correlation (R ≥ 0.88), except for basophils. Flagging performance exhibited sensitivity over 90% for majority of alarm messages and very high negative predictive value (over 95%). CONCLUSION: UniCel DxH900 Coulter analyzer provides reliable results and fully comparable to DxH800. DxH900 is an accurate, highly precise analyzer with good analytical performances to be used effectively in high-volume laboratories.

Diagnostic performance of the ClearLLab 10C B cell tube.

INTRODUCTION: Pre-analytical and analytical errors can threaten the reliability of flow cytometry (FC) results. A potential solution to some of these is the use of dry, pre-mixed antibodies, such as the ClearLLab 10C system. The purpose of the present study was to compare the diagnostic performance of the ClearLLab 10C B cell tube with that of our standard laboratory practice. METHODS: We compared the diagnoses made with the ClearLLab 10C B cell tube (experimental strategy) with those made with standard laboratory practice (standard strategy). Samples were selected aiming for representation of the full spectrum of B cell disorders, with an emphasis on mature B cell malignancies, as well as healthy controls. RESULTS: We included 116 samples (34 normal controls, 4 acute lymphoblastic leukemias, 54 mature lymphoproliferative disorders in peripheral blood and bone marrow, 3 myelomas, 6 bone marrow samples with involvement by lymphoma and 1 with elevated hematogone count, 14 lymph node samples, 1 cerebrospinal fluid, and 1 pleural effusion). There were two diagnostic errors (1.7%). The agreement between the two strategies in the percentage of CD19 cells and fluorescence intensity of CD5, CD19, CD20, CD200, and CD10 was very good. CONCLUSIONS: In this study, the ClearLLab 10C B cell tube performed similarly to our standard laboratory practice to diagnose and classify mature B cell malignancies.

Positive predictive value of CD200 positivity in the differential diagnosis of chronic lymphocytic leukemia.

BACKGROUND: The role of CD200 in the differential diagnosis of chronic lymphocytic leukemia (CLL) and classical mantle cell lymphoma (MCL) is well established. Its role in the differential diagnosis of CLL and other lymphoproliferative disorders (LPD) is less clear, in particular its positive predictive value (PPV). MATERIALS AND METHODS: We conducted a systematic review of the use of CD200 in the differential diagnosis of CLL, MCL, and other predominantly leukemic, typically CD103-negative LPD. With the results, we then derived a curve to determine the PPV based on the prevalence of the disorders included in the differential diagnosis. RESULTS: Of 43 publications screened, 27 were included in the systematic review (5,764 patients). The median CD200 positivity rate in all studies and the percentage of CD200-positive (pooled) patients was 100% and 95% (3,061/3,208) in CLL, 4 and 8% (86/1112) in MCL and 56 and 62% (425/689) in other LPD. CONCLUSION: CD200 is suboptimal for the differential diagnosis of CLL and disorders other than nodal MCL.

Flow Cytometry in the Differential Diagnosis of CD10-Positive Nodal Lymphomas.

BACKGROUND: Differences between follicular lymphoma (FL) and diffuse large B-cell lymphoma/high-grade B-cell lymphoma (DLBCL/HGBL) by flow cytometry are underexplored. METHODS: We retrospectively assessed flow cytometry results from 191 consecutive lymph node biopsies diagnosed with FL or DLBCL/HGBL. RESULTS: The only parameters that differed between the 2 groups in the derivation cohort were forward scatter and side scatter (P < 10-6; area under the curve [AUC], 0.75-0.8) and %CD23 (P = .004; area under the receiver characteristic operating curve, 0.64). However, since light scatter characteristics did not distinguish between grade 3 FL and DLBCL/HGBL, we set out to develop a model with high sensitivity for the exclusion of the latter. Several models, including FS and %CD23, were tested, and 2 models showed a sensitivity of >0.90, with negative predictive values of ≥0.95, albeit with low specificity (0.45 to 0.57). CONCLUSION: Two simple models enable the exclusion of DLBCL/HGBL with a high degree of confidence.

Dabigatran for catastrophic antiphospholipid syndrome.

: Vitamin K antagonists (VKA) remain the treatment of choice for catastrophic antiphosphilipid syndrome (CAPS). However, when VKAs do not work for a specific patient, direct oral anticoagulants (DOAC) may be a valid therapeutic alternative. We present a patient with a psychiatric disorder and CAPS who was noncompliant to VKA and low-molecular-weight heparin. He was started on dabigatran and has remained thrombosis-free for 8 years. Due to CAPS he has developed progressive renal failure but dabigatran levels were within the expected range. In conclusion, this case report provides anecdotic evidence that dabigatran may be of use in patients with high-risk APS in whom VKA are not an option.

Indications and use of, and incidence of major bleeding with, antithrombotic agents in myelodysplastic syndrome.

Myelodysplastic syndrome (MDS) and antithrombotic medication both increase the risk of bleeding. We set out to analyze the prevalence of use, indications and bleeding risk of antithrombotic therapy in patients with MDS in a retrospective, single-center study including all patients with MDS with >20 × 109/L platelets. 193 patients (59% male, median age 75 years) were included; 122 did not receive antithrombotic treatment, 51 received antiplatelet agents and 20 received anticoagulants. The cumulative incidence of major bleeding was higher in both the antiplatelet group (11.8% at 4 years, 95% confidence interval [95%CI]: 4.7-22.3%) and the anticoagulation group (21.2% at 4 years, 95%CI 6-42.5%) than in the control group (2.8% at 4 years 95%CI: 0.7-7.3%). The prevalence of use of antithrombotic medication in this cohort of patients with MDS was high and bleeding risk was increased in these patients.

Magnitudes biológicas que tiene interés medir de modo urgente / Biological markers in emergency laboratory

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