Electronic Journal of the International Federation of Clinical Chemistry and Laboratory Medicine最新文献

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.

Anti-HMGCR, which was first identified in 2010, has emerged as an important mechanism of myopathogenesis in patients with exposure to statins. The availability of new detection methods has expanded the phenotypic spectrum with a subtype of population that hasn't been exposed to the drug and whose clinical, analytical, and pathological manifestations are similar. The observation by immunofluorescence of a highly specific pattern known as HALIP (HMGCR Associated Liver Immunofluorescence Pattern) can be useful in the detection of these antibodies.

Background: This study was planned to investigate how the positivization time of a SARS-CoV-2 rapid antigen self-test may correlate with SARS-CoV-2 nucleocapsid (N) antigen concentration measured with a quantitative laboratory-based immunoassay.

Methods: Paired nasopharyngeal (healthcare-collected) and nasal (self-collected) samples were taken from patients undergoing routine SARS-CoV-2 testing. The concentration of SARS-CoV-2 antigen nucleocapsid (N) was assayed with Liaison SARS-CoV-2 Antigen test, whilst the time of positivization of COVID-VIRO ALL rapid diagnostic test (RDT) was concomitantly measured and then compared SARS-CoV-2 viral load measured with Liaison SARS-CoV-2 Antigen test and expressed as Median Tissue Culture Infectious Dose (TCID50)/mL.

Results: The study sample consisted of 32 paired specimens which tested positive with COVID-VIRO ALL IN RDT and had SARS-CoV-2 N protein concentration measured with Liaison SARS-CoV-2 Antigen test. A highly significant correlation was found between SARS-CoV-2 viral antigen concentration and RDT positivization time (r=-0.64; 95%CI, -0.81 to -0.38; p<0.001). At the >1500 TCID50/mL threshold of the Liaison SARS-CoV-2 Antigen test, the positivization time of the COVID-VIRO ALL IN RDT displayed high accuracy (93.7%). A positivization time <42 sec enabled to identify patients with high SARS-CoV-2 antigen concentration (i.e., >1500 TCID50/mL) with 91.3% negative and 100% positive predictive values.

Conclusion: Self-testing using COVID-VIRO ALL IN RDT could be reliably used for garnering valuable information on the actual SARS-CoV-2 viral antigen concentration in respiratory samples.

Isolated increase in thyrotropin stimulating hormone (TSH) in a clinically euthyroid patient may be caused by the formation of a macromolecule between TSH and autoantibodies causing discordant thyroid function test results. Despite the effort to eliminate interferences in immunoassays, these assays are still vulnerable to different interferences. Immunoassay interferences may cause erroneous results and lead to misdiagnosis which may subject a patient to unnecessary investigations and treatment. Immunoassays are affected by multiple substances; these may be endogenous or exogenous such as heterophile antibodies, autoantibodies, macromolecules, and human anti-mouse antibodies. This case reports a 47-year-old African woman who presented with a persistent elevated TSH with thyroid hormones within normal reference limits. She was found to have a macro-TSH which was associated with IgA paraprotein.

Herein we described a retrospective analysis of a 13-year-old female patient with facial dysmorphia and immune disorder caused by BCL11B gene mutation. The patient upon physical examination presented a particular face (thin eyebrows, small mandible, and widened eye distance), delayed language and motor development. Supplementary examination showed expansion of CD8+, absence of type 2 Innate Lymphoid Cells, increased IgG and altered distribution of T cells. Genetic testing revealed a heterozygous frameshift variation in exon 4 of the BCL11B gene; c.1887_c.1893delCGGCGGG (p.Gly630Glyfs*91). Finally, a BCL11B gene mutation could lead to abnormal development of the nervous and immune systems, therefore, it is necessary to consider this syndrome in patients with the clinical and immunological phenotype described below.

Among the five major classes of lipoprotein particles, low-density lipoprotein-cholesterol (LDL-C) is the primary lipoprotein risk factor for the development of cardiovascular diseases (CVD) through the promotion of atherosclerotic pathogenesis. Therefore, it is of paramount importance to accurately measure the plasma concentration of LDL-C using an appropriate method to examine the risk of CVD and determine the efficacy of therapeutic interventions to reduce the cholesterol level and examine the risk assessment strategy. At present, there is a wide variety of methods available for LDL-C measurement. In this review, we have outlined the commonly used methods of LDL-C measurement. These methods have been classified into non-automated analytical methods, calculation methods, and automated direct measurement of LDL-C. We have also described some recently proposed promising calculation methods which are being considered for clinical adoption. This current review could assist the clinicians to have a better understanding regarding the measurement techniques and comparative utilities of different methods of LDL-C measurement and guide them to select an appropriate method based on accuracy, turnaround time, and cost of test.

Purpose: Serum albumin is in contact with practically all cells in the human body, including tumor cells in cancer patients. The purpose of this study was to explore whether cancer cells affect post-translational modifications (PTMs) of albumin.

Material and methods: Mass spectrometry was used to identify the PTMs. Purified human serum albumin was incubated with human breast cancer cells MDA-MB-231, MDA-MB-468, MCF7, or kept in water or in cell culture media. PTMs which were affected upon exposure of the albumin to cancer cells were identified. Three-dimensional analysis was performed to locate PTMs in albumin.

Results: We report here that an exposure to human breast cancer cells affected post-translational modifications (PTMs) of 14 peptides of human serum albumin (HSA). PTMs at 8 peptides were observed upon exposure of HSA to metastatic MDA-MB-231 and MDA-MB-468 breast cancer cells. PTMs at another 6 peptides were lost in MDA-MB-231 and MDA-MB-468 cells, while these 6 PTMs were observed in HSA exposed to conditionally tumorigenic MCF7 cells, or in HSA kept in water or a cell culture medium. Cancer cell altered phosphorylation, deamidation followed by methylation, acetylation, myristylation, palmitoylation, methylation, cysteine persulfide, and S-6-FMN cysteine modifications were detected in HSA. These PTMs locate predominantly in IB and IIA domains of HSA. Three-dimensional analysis showed that this region corresponds to the lipid-binding site and Sudlow's site 1.

Conclusion: Data reported here show that 14 PTMs of human serum albumin can be modified upon its exposure to human breast cancer cells.

An M-protein identified on electrophoresis is conventionally quantified by integrating the M-spike from baseline (PD), invariably including some irrelevant/background proteins. The use of an alternative approach that skims the M-spike tangentially thereby excluding the background proteins (TS), however, has been scanty. We report herein a case in which PD overestimated the M-proteins inconsistently, leading to confusion over relapse in a multiple myeloma patient. At diagnosis, a 65-year old male had an IgG kappa M-spike of 44 g/L which decreased to 6 g/L (PD) following chemotherapy. Six weeks after autologous stem cell transplantation (ASCT), two M-spikes measuring respectively 10 and 5 g/L emerged. Together with decreases in hemoglobin and blood cell counts, a relapse was suspected. Bone marrow examinations, however, did not reveal any significant plasmacytosis or clonal restriction. Re-analyses by TS reduced the original M-protein estimations by 12% and 88% pre- and post-ASCT respectively, and corroborated the disease activity/status consistently.

Background: The lysis of platelets during in vitro coagulation leads to increased potassium concentrations.We aimed to establish the cut-off value for platelet count interfering serum potassium and to estimate the percentage of cases of pseudohyperkalemia and pseudonormokalemia in our hospital.

Materials and methods: Individuals diagnosed with essential thrombocytosis (2010-2019) based on the WHO criteria for the classification of myeloid neoplasms and acute leukemia were considered.The cut-off value for the interference of platelet count on serum potassium results was calculated using the reference change value. Sensitivity and specificity were calculated using a ROC-curve, and the size of the effect by the Cohen's d.The clinical impact of both phenomena was assessed by reviewing the medical records of individuals classified as such, and also looking for potential cases in 2019 on the laboratory information system.

Results: Fifty-four individuals with essential thrombocytosis were included. Potassium concentration correlated with platelet count (P-value<0.001; Spearman's ρ =0.394) in serum. The cut-off value of platelet count interfering potassium was 598x10³/μL [CI95%: 533-662x10³/μL], with an associated sensitivity and specificity of 0.67 [CI95%:0.52-0.80] and 0.58 [CI95%:0.42-0.72] respectively.The medical records of patients classified as pseudohyperkalemia or pseudonormokalemia did not include any medical action for the modification of potassium levels. In 2019, up to 0.14% of the total serum potassium determinations were susceptible to be pseudohyperkalemia or pseudonormokalemia.

Conclusion: This study provides a cut-off value for platelet count interfering serum potassium concentrations, and brings to light not only pseudohyperkalemia-related issues, but also the pseudonormokalemia phenomenon, which usually goes unnoticed.