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Introduction: Two new formulas, the Martin-Hopkins and the Sampson formula, were recently developed to overcome shortcomings of the Friedewald formula for calculating LDL-cholesterol. We aimed to compare the concordance of the two formulas with apolipoprotein B (apoB), a surrogate marker of the number of LDL particles. Materials and methods: In a study of serum lipid data of 1179 patients who consulted the AZ St-Jan Hospital Bruges for cardiovascular risk assessment, the correlation and concordance of the Friedewald, Martin-Hopkins and Sampson formulas with apoB concentration, measured by immunonephelometry, were determined and compared. Results: The Martin-Hopkins formula showed significantly higher correlation coefficient than the Friedewald formula with apoB in the entire dataset and in patients with low LDL-cholesterol < 1.8 mmol/L. Both Martin-Hopkins and Sampson formulas yielded > 70% concordance of LDL-cholesterol with regard to treatment group classification based on population-equivalent thresholds of apoB in hypertriglyceridemic patients (2-4.5 mmol/L), with the highest concordance (75.6%) obtained using Martin-Hopkins formula vs. 60.5% with Friedewald formula. Conclusion: The Martin-Hopkins (and, to a lesser extent, Sampson) formula is more closely associated with the number of LDL particles than Friedewald formula. This, in combination with literature evidence of lesser accuracy of the Friedewald formula, is an argument to switch from Friedewald to a modified, improved formula. [ABSTRACT FROM AUTHOR]

Accordingly, efforts by IFCC to develop a new Primary Reference Measurement System with a mass spectroscopy-based primary reference method and serum-based reference materials are well underway and will allow true SI-traceable standardization of apolipoproteins [[3]]. To declare a particular method as standardized, a clinical laboratory or IVD manufacturer must demonstrate adequate agreement between their measurement and a consensus reference method and/or consensus reference material to establish metrological traceability of results. In this issue of I Clin Chem Lab Med i , the study by Smit et al. [[1]] from Leiden University Medical Center (LUMC, The Netherlands) highlights the importance of a standardized preanalytical phase for accurate mass spectrometry applications in clinical chemistry. [Extracted from the article]

• Harmonization of lipid profiles across European laboratories is poor. • Two-thirds of laboratories use nonfasting lipid measurements. • Less than 50% of laboratories flag guideline-recommended LDLC thresholds. • Less than 50% of laboratories automatically calculate non-HDLC. • Less than one-fourth of laboratories apply alert values for FH. The CArdiac MARker Guidelines Uptake in Europe Study (CAMARGUE) initiated by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) aims to survey the current use of evidence-based guidelines for dyslipidemia testing in Europe. In 2019 a web-based questionnaire was distributed via EFLM National Societies to clinical laboratories in Europe. Questions covered pre-analytics, analytical methods, measurement units, flagging of decision thresholds, and use of decision-enhancing comments. Returns were obtained from 452 laboratories from 28 countries. Most laboratories always use nonfasting blood samples for lipid assays (66%). Lipid profiles are reported in mmol/L by 59% of the laboratories, mainly from 14 countries promoting the use of SI units. Important differences in flagging of decision thresholds were observed, with less than half of the laboratories applying the guideline-recommended LDL cholesterol threshold. Only 17% of the laboratories add an alert comment when familial hypercholesterolemia is suspected and 23% when risk of pancreatitis from hypertriglyceridemia is high. There are marked differences among laboratories in Europe in terms of pre-analytical, analytical, and post-analytical lipid management that could have an important clinical impact. This relates to different availability of assays or different laboratory practices on reporting and flagging of lipid profiles. [ABSTRACT FROM AUTHOR]

The joint consensus panel of the European Atherosclerosis Society (EAS) and the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) recently addressed present and future challenges in the laboratory diagnostics of atherogenic lipoproteins. Total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDLC), LDL cholesterol (LDLC), and calculated non-HDLC (=total – HDLC) constitute the primary lipid panel for estimating risk of atherosclerotic cardiovascular disease (ASCVD) and can be measured in the nonfasting state. LDLC is the primary target of lipid-lowering therapies. For on-treatment follow-up, LDLC shall be measured or calculated by the same method to attenuate errors in treatment decisions due to marked between-method variations. Lipoprotein(a) [Lp(a)]-cholesterol is part of measured or calculated LDLC and should be estimated at least once in all patients at risk of ASCVD, especially in those whose LDLC declines poorly upon statin treatment. Residual risk of ASCVD even under optimal LDL-lowering treatment should be also assessed by non-HDLC or apolipoprotein B (apoB), especially in patients with mild-to-moderate hypertriglyceridemia (2–10 mmol/L). Non-HDLC includes the assessment of remnant lipoprotein cholesterol and shall be reported in all standard lipid panels. Additional apoB measurement can detect elevated LDL particle (LDLP) numbers often unidentified on the basis of LDLC alone. Reference intervals of lipids, lipoproteins, and apolipoproteins are reported for European men and women aged 20–100 years. However, laboratories shall flag abnormal lipid values with reference to therapeutic decision thresholds. [ABSTRACT FROM AUTHOR]

The joint consensus panel of the European Atherosclerosis Society (EAS) and the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) recently addressed present and future challenges in the laboratory diagnostics of atherogenic lipoproteins. Total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, and calculated non-HDL cholesterol (=total – HDL cholesterol) constitute the primary lipid panel for estimating risk of atherosclerotic cardiovascular disease (ASCVD) and can be measured in the nonfasting state. LDL cholesterol is the primary target of lipid-lowering therapies. For on-treatment follow-up, LDL cholesterol shall be measured or calculated by the same method to attenuate errors in treatment decisions due to marked between-method variations. Lipoprotein(a)-cholesterol is part of measured or calculated LDL cholesterol and should be estimated at least once in all patients at risk of ASCVD, especially in those whose LDL cholesterol decline poorly upon statin treatment. Residual risk of ASCVD even under optimal LDL-lowering treatment should be also assessed by non-HDL cholesterol or apolipoprotein B, especially in patients with mild-to-moderate hypertriglyceridemia (2–10 mmol/L). Non-HDL cholesterol includes the assessment of remnant lipoprotein cholesterol and shall be reported in all standard lipid panels. Additional apolipoprotein B measurement can detect elevated LDL particle numbers often unidentified on the basis of LDL cholesterol alone. Reference intervals of lipids, lipoproteins, and apolipoproteins are reported for European men and women aged 20–100 years. However, laboratories shall flag abnormal lipid values with reference to therapeutic decision thresholds. Image 1 • Total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, and calculated non-HDL cholesterol (=total – HDL cholesterol) constitute the primary lipid panel for estimating risk of atherosclerotic cardiovascular disease (ASCVD) and can be measured in the nonfasting state. • LDL cholesterol is the primary target of lipid-lowering therapies. • Lipoprotein(a)-cholesterol is part of measured or calculated LDL cholesterol and lipoprotein(a) should be measured at least once in all patients. • Residual risk of ASCVD even under optimal LDL-lowering treatment should be also assessed by non-HDL cholesterol or apolipoprotein B, especially in patients with mild-to-moderate hypertriglyceridemia (2-10 mmol/L). • Non-HDL cholesterol includes the assessment of remnant lipoprotein cholesterol and shall be reported in all standard lipid panels. • Laboratories shall flag abnormal lipid values with reference to therapeutic decision thresholds. [ABSTRACT FROM AUTHOR]

Objective The European Federation of Laboratory Medicine (EFLM) and the Union of European Medical Specialists (UEMS) joint Working Group on guidelines recently proposed a checklist to help standardize the description of laboratory investigations in clinical practice guidelines (CPG). Methods Nine CPGs or consensus documents published from 2011 to 2013 describing the investigation of chest pain, diagnosis of acute coronary syndrome, or myocardial infarction were evaluated against the published checklist. Results Clinical use of troponin analysis are commonly dealt with but the publications present variable, vague and sometimes conflicting information regarding this laboratory test being very much relied on upon making a diagnosis of acute coronary syndrome. Most of the laboratory related checklist items are not considered or need to be updated e.g. suggested analytical quality goals are not applicable for the high sensitive assays and important interferences that may lead to false positive or negative diagnoses are commonly not mentioned. Conclusion The current paper sums up important analytical and biological issues related to troponin assays and gives suggestions for analytical quality goals that could be included in CPG's. [ABSTRACT FROM AUTHOR]

Abstract: Background: Despite international standardization programs for LDLc and HDLc measurements, results vary significantly with methods from different manufacturers. We aimed to simulate the impact of analytical error and hypertriglyceridemia on HDLc- and LDLc-based cardiovascular risk classification. Methods: From the Dutch National EQA-2012 external quality assessment of 200 clinical laboratories, we examined data from normotriglyceridemic (∼1 mmol/l) and hypertriglyceridemic (∼7 mmol/l) serum pools with lipid target values assigned by the Lipid Reference Laboratory in Rotterdam. HDLc and LDLc were measured using direct methods of Abbott, Beckman, Siemens, Roche, Olympus, or Ortho Clinical Diagnostics. We simulated risk reclassification using HDL- and sex-specific SCORE multipliers considering two fictitious moderate-risk patients with initial SCORE 4% (man) and 3% (woman). Classification into high-risk treatment groups (LDLc >2.50 mmol/l) was compared between calculated LDLc and direct LDLc methods. Results: Overall HDLc measurements in hypertriglyceridemic serum showed negative mean bias of −15%. HDL-multipliers falsely reclassified 70% of women and 43% of men to a high-risk (SCORE >5%) in hypertriglyceridemic serum (P < 0.0001 vs. normotriglyceridemic serum) with method-dependent risk reclassifications. Direct LDLc in hypertriglyceridemic serum showed positive mean bias with Abbott (+16%) and Beckman (+14%) and negative mean bias with Roche (−7%). In hypertriglyceridemic serum, 57% of direct LDLc measurements were above high-risk treatment goal (2.50 mmol/l) vs. 29% of direct LDLc (33% of calculated LDLc) in normotriglyceridemic sera. Conclusion: LDLc and HDLc measurements are unreliable in severe hypertriglyceridemia, and should be applied with caution in SCORE risk classification and therapeutic strategies. [Copyright &y& Elsevier]

Background: Correct information provided by guidelines may reduce laboratory test related errors during the pre-analytical, analytical and post-analytical phase and increase the quality of laboratory results. Methods: Twelve clinical practice guidelines were reviewed regarding inclusion of important laboratory investigations. Based on the results and the authors' experience, two checklists were developed: one comprehensive list including topics that authors of guidelines may consider and one consisting of minimal standards that should be covered for all laboratory tests recommended in clinical practice guidelines. The number of topics addressed by the guidelines was related to involvement of laboratory medicine specialists in the guideline development process. Results: The comprehensive list suggests 33 pre- analytical, 37 analytical and 10 post-analytical items. The mean percentage of topics dealt with by the guidelines was 33% (median 30%, range 17%-55%) and inclusion of a laboratory medicine specialist in the guideline committee significantly increased the number of topics addressed. Information about patient status, biological and analytical interferences and sample handling were scarce in most guidelines even if the inclusion of a laboratory medicine specialist in the development process seemingly led to increased focus on, e.g., sample type, sample handling and analytical variation. Examples underlining the importance of including laboratory items are given. Conclusions: Inclusion of laboratory medicine specialist in the guideline development process may increase the focus on important laboratory related items even if this information is usually limited. Two checklists are suggested to help guideline developers to cover all important topics related to laboratory testing. [ABSTRACT FROM AUTHOR]

Lipoprotein-related risk of cardiovascular disease (CVD) can be adequately predicted in subjects with elevated total cholesterol and low-density lipoprotein (LDL-)cholesterol using the available guidelines. However, individuals with dyslipidemia can have normal total- and LDL-cholesterol concentrations. Many statin-treated patients remain at high residual risk of CVD despite achieving LDL goals. The small dense LDL phenotype, frequently presenting with hypertriglyceridemia and low high-density lipoprotein (HDL-)cholesterol (lipid triad), may contribute to failure to identify and treat high-risk individuals. Therefore, calculated non-HDL-cholesterol is recommended as secondary therapeutic target to LDL-cholesterol in patients with hypertriglyceridemia and mixed dyslipidemia. On-treatment apolipoprotein B adds prognostic information to LDL- and non-HDL-cholesterol by indicating the total number of atherogenic lipoproteins, regardless of their cholesterol content. Risk may be higher than indicated in the risk estimation systems in additional subjects with elevated lipoprotein(a) and homocysteine concentrations. To improve the (post-)post-analytical phase of lipid tests, aiming for maximal health outcome effectiveness of test interpretation and utilization, laboratory professionals should deliver clinical added value services by providing readily interpreted and guideline-adjusted test reports, interpretative commenting, proactive reflex testing or recommending additional tests, and joining multidisciplinary cooperations in guideline development and cost/benefit studies. [ABSTRACT FROM AUTHOR]

To face the economic pressures arising from the current socio-economic conjuncture, hospital laboratories are endangered by an increasing trend towards the outsourcing of clinical laboratory tests to external (mega-) laboratories. This should allow hospitals to meet their economic requirements, but with an increased risk of loss of medical quality and, mid- to long-term, loss of cost effectiveness of healthcare at the national level. To anticipate current developments (economical and technological) that inevitably will affect the future of laboratory medicine, hospital laboratories should be proactive and enhance efficiency, reduce costs by consolidation, integrate into regional networks, and form alliances or partnerships. To create additional value, the core competency of laboratory professionals must be refocused to provide medical knowledge services (consultative support to clinicians) related to in vitro diagnostic testing. To integrate cost-efficiency with medical quality, implementation of a matricial organization – operational vs. biomedical level – could be an interesting approach. This integrated structure should create total quality of laboratory testing, managing the entire medical diagnostic cycle from the pre-preanalytical to post-postanalytical phase. Clin Chem Lab Med 2009;47:1195–201. [ABSTRACT FROM AUTHOR]

Low-density lipoproteins (LDLs) are susceptible to structural modifications by oxidation, particularly the small dense LDL particles. The formation of lipid peroxidation derivates, such as thiobarbituric reactive substances, conjugated dienes, lipid hydroperoxides, and aldehydes, is associated with changes in apolipoprotein conformation and affects the functional properties of LDLs. Oxidized LDL (oxLDL) formation in the subendothelial space of the arterial wall is a key initiating step in atherosclerosis because it contributes to foam cell generation, endothelial dysfunction, and inflammatory processes. In the last decade, immunoassays were developed using monoclonal antibodies against oxidation-dependent epitopes of LDL which made it possible to directly measure oxLDL in the circulation. Increased circulating oxLDL concentrations have been related to cardiovascular disease in some studies, although not always independently after adjustment of classical lipid markers. The Asklepios Study, investigating 2524 healthy middle-aged subjects, showed that circulating oxLDL is affected by many biological and lifestyle factors, as well as (generalized) subclinical atherosclerosis. Clin Chem Lab Med 2009;47:128–37. [ABSTRACT FROM AUTHOR]

Background: Haptoglobin (Hp) polymorphism has been associated with blood pressure regulation and essential hypertension. We investigated Hp polymorphism in patients with preeclampsia. Methods: A total of 60 Caucasian women with preeclampsia were prospectively followed from hospital admission until delivery. Serum Hp phenotypes 1-1, 2-1, and 2-2 were determined by starch gel electrophoresis and compared with those in 200 normotensive controls of the same geographic and ethnic origin. Blood pressure and laboratory markers (serum uric acid, alanine aminotransferase, aspartate aminotransferase, platelet count, and 24-h proteinuria) were compared according to Hp phenotypes of preeclamptic women. Results: We found a higher Hp1 allele frequency in the preeclamptic group than in normotensive controls (0.517 vs. 0.400, p<0.05). The Hp 1-1 phenotype was present in 28% of preeclamptic patients vs. 16% of the controls, with an odds ratio (95% CI) of 2.08 (1.05–4.08) for Hp 1-1 vs. the other Hp phenotypes. Diastolic (p<0.005) and systolic (p<0.05) blood pressure and proteinuria (p<0.05) were highest in Hp 1-1 patients. Other laboratory markers were not significantly different between Hp phenotype subgroups. Conclusions: The Hp1 allele frequency was higher among preeclamptic patients and the Hp 1-1 phenotype was associated with more severe hypertension and proteinuria. Clin Chem Lab Med 2006;44:924–8. [ABSTRACT FROM AUTHOR]

Abstract: High-density lipoprotein cholesterol (HDL-C) comprises a family of particles with differing physicochemical characteristics. Continuing progress in improving HDL-C analysis has originated from two separate fields—one clinical, reflecting increased attention to HDL-C in estimating risk for coronary heart disease (CHD), and the other analytical, reflecting increased emphasis on finding more reliable and cost-effective HDL-C assays. Epidemiologic and prospective studies established the inverse association of HDL-C with CHD risk, a relationship that is consistent with protective mechanisms demonstrated in basic research and animal studies. Atheroprotective and less atheroprotective HDL subpopulations have been described. Guidelines on primary and secondary CHD prevention, which increased the workload in clinical laboratories, have led to a revolution in HDL-C assay technology. Many analytical techniques including ultracentrifugation, electrophoresis, chromatography, and polyanion precipitation methods have been developed to separate and quantify HDL-C and HDL subclasses. More recently developed homogeneous assays enable direct measurement of HDL-C on an automated analyzer, without the need for manual pretreatment to separate non-HDL. Although homogeneous assays show improved accuracy and precision in normal serum, discrepant results exist in samples with atypical lipoprotein characteristics. Hypertriglyceridemia and monoclonal paraproteins are important interfering factors. A novel approach is nuclear magnetic resonance spectroscopy that allows rapid and reliable analysis of lipoprotein subclasses, which may improve the identification of individuals at increased CHD risk. Apolipoprotein A-I, the major protein of HDL, has been proposed as an alternative cardioprotective marker avoiding the analytical limitations of HDL-C. [Copyright &y& Elsevier]

Abstract: Background: In routine semen analysis, discrepancies may occur between sperm acrosin activity test results and sperm acrosomal morphology. Methods: Discrepant test results of sperm acrosin activity (spectrophotometric assay) vs. sperm morphology (strict criteria) in the initial diagnostic investigation of 107 infertile couples were evaluated with respect to fertilization rate (% oocytes with 2 pronuclei) further obtained in IVF treatment. Results: Acrosin activity positively correlated with sperm morphology (% normal forms) (r=0.537) and fertilization rate (r=0.526). ROC curves for the prediction of ≥50% fertilization rate were comparable for acrosin activity and sperm morphology, with optimal cutoff values at 25 μIU/106 sperm and 10%, respectively. In multiple regression analysis, sperm acrosin activity (P=0.002) predicted fertilization rate independently of sperm morphology (P<0.001) and sperm vitality (eosin–nigrosin stain) (P=0.03). Acrosin activities ≥25 μIU/106 sperm were observed in 36% of severe teratozoospermic samples (≤4% normal spermatozoa) associated with low fertilization rate. Twenty percent of the morphologically normal ejaculates showed a low acrosin activity (<25 μIU/106 sperm) and low hypoosmotic swelling test (HOST) scores (31.4±7.6%) and were associated with low fertilization rate. Conclusion: The sperm acrosin assay can help to predict sperm fertilizing capacity in IVF independently of sperm morphology. [Copyright &y& Elsevier]

We studied the value of serum amyloid A (SAA), a first-class acute-phase protein, as a marker for coronary heart disease (CHD) in a middle-aged male population. In a working population of 16 307 men (age, 35–59 years), 446 cases had a history of CHD or prominent Q:QS waves on electrocardiogram. For each case, two matched controls were investigated. SAA, measured by immunonephelometry, was correlated with other acute-phase proteins, cardiovascular risk factors, and infectious serology markers. SAA concentrations were significantly higher in the cases than in controls (P<0.05) and correlated with serum C-reactive protein (CRP) (r=0.61), plasma fibrinogen (r=0.39), serum haptoglobin (r=0.26), and body mass index (r=0.13) (P<0.001). Serum CRP is a better marker for CHD than SAA, which showed discriminative power only in a univariate model comparing highest versus lowest tertile (odds ratio, 1.39; 95% confidence interval, 1.03–1.87). Neither SAA nor other acute-phase proteins correlated with Chlamydia pneumoniae immunoglobulin (Ig)G, Helicobacter pylori IgG and IgA, and cytomegalovirus IgG. In conclusion, although SAA has a discriminative value for CHD, serum CRP is to be preferred as a first-class acute-phase reactant for detection of the disease. [Copyright &y& Elsevier]

The Contrast Media Safety Committee of the European Society of Urogenital Radiology has, together with the Preanalytical Phase Working Group of the EFLM Science Committee, reviewed the literature and updated its recommendations to increase awareness and provide insight into these interferences. Clinical relevance statement: Contrast Media may interfere with clinical laboratory tests. Awareness of potential interference may prevent unwanted misdiagnosis. Key Points: • Contrast Media may interfere with clinical laboratory tests; therefore awareness of potential interference may prevent unwanted misdiagnosis. • Clinical Laboratory tests should be performed prior to radiological imaging with contrast media or alternatively, blood or urine collection should be delayed, depending on kidney function. [ABSTRACT FROM AUTHOR]

Abstract: B cells play a role in atherosclerosis. B lymphocytes may reduce the progression of vascular disease. Antibody production against modified auto-antigens is an element in the atheroprotective involvement of B lymphocytes. Paradoxical evidence is emerging from animal studies that suggest a proatherogenic B-cell behaviour independently of autoantibody production. One aspect that has received limited consideration is the role of genetic susceptibility modulated by extracellular matrix proteins. Haptoglobin is a polymorphic glycoprotein that binds to CD22 on B lymphocytes. Hp phenotypes show an important molecular heterogeneity. Hp 2-2 has been linked to an increased susceptibility for atherosclerosis. Haptoglobin and its polymorphism play a role in B-cell migration and function. Hp phenotypes may influence B-T cell dialogue and T cell activation. Haptoglobin is involved in the interplay of lymphocytes, neutrophils, and monocytes. Haptoglobin binds to the CD11b/CD18 receptor and to mast cells. HDL particles can become pro-inflammatory through interactions of Hp-Hb complexes with apolipoprotein A1. Haptoglobin is a chemoattractant to pre-B lymphocytes and monocytes. Beyond the conventional view of haptoglobin as a marker of hemolysis, several findings point towards an immunomodulatory effect of haptoglobin in B-cell mediated progression of atherosclerosis. The balance between proatherogenic and protective immunological properties of the different Hp phenotypes determines if lesions progress or regress. Clinical studies indicate a strong association between the Hp 2-2 phenotype and a more frequent onset of diabetic complications and cardiovascular disease. Findings in animal models (where no haptoglobin polymorphism is present) cannot always be extrapolated to humans. [Copyright &y& Elsevier]

The Contrast Media Safety Committee of the European Society of Urogenital Radiology has, together with the Preanalytical Phase Working Group of the EFLM Science Committee, reviewed the literature and updated its recommendations to increase awareness and provide insight into these interferences. [ABSTRACT FROM AUTHOR]

The article reports on haptoglobin polymorphism and serum ferritin concentration in ageing subjects. In randomly selected control subjects, in blood donors homozygous for the HFE C282Y mutation, and in first-time blood donors lacking the HFE mutations, it was found that their was no influence of Hp type on transferrin saturation and serum ferritin concentration. It was found that the influence of Hp type on serum iron status was exclusively present in males aged 18-50 years. The influence of Hp 2-2 type on serum ferritin concentrations cannot be observed in subjects aged >50 years.

Background: Calprotectin is a 36 kDa calcium and zinc binding protein. An increased level of calprotectin points towards inflammatory bowel disease. However, the biomarker calprotectin shows 14 potential cleavages sites for trypsin. Next to trypsin, also the presence of its inhibitor α1-antitrypsin after a gastrointestinal bleeding may affect calprotectin testing. In this study, effects of trypsin and α1-antitrypsin as potential confounders for faecal calprotectin testing are investigated. Methods: An in vitro model was created. As calprotectin source, leukocytes were isolated and subsequently lysed (1% Triton X-100) and diluted in faecal matrix. Trypsin digestion was carried out by adding trypsin. Incubation occurred for 24 h or 48 h (37 °C). To study the influence of α1-antitrypsin on trypsin, the same experiment was repeated after adding serum containing α1-antitrypsin. Results: In vitro experiments enabled monitoring of the faecal calprotectin digestion, leading to loss of immunoreactivity. Trypsin activity was a potential confounder in the interpretation of calprotectin, in particular for proximal lesions, where exposure of calprotectin to trypsin is prolonged. Relative calprotectin loss was proportional to the amount of trypsin. Decrease of calprotectin was more pronounced after 48 h of incubation in comparison to 24 h of incubation. Analogue experiments also showed stable calprotectin values after adding α1-antitrypsin. Conclusions: Transit time, trypsin activity and addition of blood as a source of α1-antitrypsin may be regarded as potential confounders in the interpretation of calprotectin results. Age-related cut-off values depending on the anatomical localisation of the lesions could improve the diagnostic efficiency of calprotectin testing. [ABSTRACT FROM AUTHOR]

Abstract: Background: Inflammation processes are considered important links between classical lipid risk factors and the progression of atherosclerosis. The interrelationship of high density lipoproteins (HDL) and apolipoprotein apoA-1 with acute phase proteins and cytokines was examined in a clinical setting of patients with angina pectoris. Methods: On exclusion criteria (myocardial infarction, heart failure, CHD>2years, anticoagulant therapy), 198 patients were recruited and were subdivided according to angiographically documented stenosis, no stenosis vs. =50% stenosis, in accordance with CASS guidelines. Lipids, apoA-1 and apoB, C-reactive protein (hs-CRP), fibrinogen, serum amyloid A (SAA) and cytokines (IL-6, IL-8, IL-10, IL2R, TNFα) were measured. Results: Low HDL-C (and apoA-I) is associated with advanced coronary stenosis (=50%) and with the number of diseased vessels, independent of age, gender, diabetes, smoking and lipid-lowering therapy. In contrast to hs-CRP and fibrinogen, SAA as well as cytokine levels were not significantly associated with stenosis. SAA (P=0.0003) and diabetes (P=0.0002) were strong predictors of apoA-I concentration independent of age, gender, BMI, smoking, CRP, as well as IL-6 in a multiple regression model. High SAA (P=0.0067) and TG (P=0.0123) were significant predictors of apoA-I/HDL-C ratio. However, SAA was not independently related to HDL-C. Conclusions: SAA is independently and inversely related to apoA-I but not to HDL-C in patients with angina pectoris, reflecting the effect of SAA on the quality of HDL particles. However, HDL-c but not SAA is inversely related to the degree of coronary artery stenosis. [Copyright &y& Elsevier]

Abstract: Introduction: We evaluated the accuracy of three automated assays for 25(OH)D measurement in comparison to ID-XLC-MS/MS in hemodialysis patients, considering the importance of their vitamin D status and reported discrepant results obtained with automated assays. Methods: All three assays were heterogeneous, competitive immunoassays or vitamin D binding protein assays on Architect (Abbott), Modular E170 (Roche) and iSYS (IDS). Measurements were performed in serum of 99 hemodialysis patients and 50 healthy subjects, double blind with a different operator and aliquot for each method. Results: Architect showed the highest deviation for hemodialysis (slope 0.3864, intercept 8.7409) and healthy subjects (slope 0.5024, intercept 6.8426) and reported significant lower results. Considering 30ng/ml as cut-off for optimal 25(OH)D concentration, Architect falsely assigned 48.5% of the hemodialysis and 6% of the healthy subgroup a suboptimal vitamin D status. iSYS results of hemodialysis patients also deviated (slope 0.6136, intercept 8.6604) but showed less discordant values than Modular E170 in patients with 25(OH)D concentrations between 10 and 40ng/ml. Conclusion: We conclude that not all automated 25(OH)D assays may be considered equally accurate in samples from hemodialysis patients compared to samples from healthy subjects. We found most deviating results with Abbott (Architect) measurements compared to ID-XLC-MS/MS in hemodialysis patients as well as in healthy subjects. We suggest a possible role of matrix effects like elevated urea or other retained metabolites in hemodialysis sera, causing incomplete binding disruption between 25(OH)D and DBP, in the poor assay accuracy. [Copyright &y& Elsevier]

The European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) initiated the CArdiac MARker Guidelines Uptake in Europe (CAMARGUE) Study to survey if current biomarker testing for heart failure (HF) in Europe is in accordance with up-dated guidelines. A web-based questionnaire was distributed to clinical laboratories via European biochemical societies in 2019. Questions covered the type of natriuretic peptide (NP) assays performed, decision limits for HF, and opinion concerning requirement of different thresholds in patients with renal failure or obesity. There were 347 participating laboratories mostly from European countries with 266 offering NP testing. NP testing was increased from 67% to 77% between 2013 and 2019. NT-proBNP remained the preferred biomarker. Recommended decision limits were implemented for BNP (85%) and better focused for NT-proBNP (40%) than in the previous survey. The survey revealed that laboratorians are willing to support the translation of adjusted cut-off values for age, gender and for patients with conditions like renal insufficiency. Guidelines stimulate clinical laboratories to offer NP testing with high value for the diagnosis and management of HF, and to present adjusted medical decision limits. Future guidelines should encourage the use of personalized cut-offs for some confounding factors. [ABSTRACT FROM AUTHOR]

Clinical practice guidelines (CPG) are written with the aim of collating the most up to date information into a single document that will aid clinicians in providing the best practice for their patients. There is evidence to suggest that those clinicians who adhere to CPG deliver better outcomes for their patients. Why, therefore, are clinicians so poor at adhering to CPG? The main barriers include awareness, familiarity and agreement with the contents. Secondly, clinicians must feel that they have the skills and are therefore able to deliver on the CPG. Clinicians also need to be able to overcome the inertia of "normal practice" and understand the need for change. Thirdly, the goals of clinicians and patients are not always the same as each other (or the guidelines). Finally, there are a multitude of external barriers including equipment, space, educational materials, time, staff, and financial resource. In view of the considerable energy that has been placed on guidelines, there has been extensive research into their uptake. Laboratory medicine specialists are not immune from these barriers. Most CPG that include laboratory tests do not have sufficient detail for laboratories to provide any added value. However, where appropriate recommendations are made, then it appears that laboratory specialist express the same difficulties in compliance as front-line clinicians. [ABSTRACT FROM AUTHOR]

Haptoglobin is an acute phase inflammatory marker. Its main function is to bind hemoglobin released from erythrocytes to aid its elimination, and thereby haptoglobin prevents the generation of reactive oxygen species in the blood. Haptoglobin levels have been repeatedly associated with a variety of inflammation-linked infectious and non-infectious diseases, including malaria, tuberculosis, human immunodeficiency virus, hepatitis C, diabetes, carotid atherosclerosis, and acute myocardial infarction. However, a comprehensive genetic assessment of the inter-individual variability of circulating haptoglobin levels has not been conducted so far. We used a genome-wide association study initially conducted in 631 French children followed by a replication in three additional European sample sets and we identified a common single nucleotide polymorphism (SNP), rs2000999 located in the Haptoglobin gene (HP) as a strong genetic predictor of circulating Haptoglobin levels (Poverall = 8.1x10-59), explaining 45.4% of its genetic variability (11.8% of Hp global variance). The functional relevance of rs2000999 was further demonstrated by its specific association with HP mRNA levels (α = 0.2360.08, P = 0.007). Finally, SNP rs2000999 was associated with decreased total and low-density lipoprotein cholesterol in 8,789 European children (Ptotal cholesterol = 0.002 and PLDL = 0.0008). Given the central position of haptoglobin in many inflammation-related metabolic pathways, the relevance of rs2000999 genotyping when evaluating haptoglobin concentration should be further investigated in order to improve its diagnostic/therapeutic and/or prevention impact. [ABSTRACT FROM AUTHOR]

Proton nuclear magnetic resonance (H-NMR)-based metabolomics enables the high-resolution and high-throughput assessment of a broad spectrum of metabolites in biofluids. Despite the straightforward character of the experimental methodology, the analysis of spectral profiles is rather complex, particularly due to the requirement of numerous data preprocessing steps. Here, we evaluate how several of the most common preprocessing procedures affect the subsequent univariate analyses of blood serum spectra, with a particular focus on how the standard methods perform compared to more advanced examples. Carr-Purcell-Meiboom-Gill 1D H spectra were obtained for 240 serum samples from healthy subjects of the Asklepios study. We studied the impact of different preprocessing steps-integral (standard method) and probabilistic quotient normalization; no, equidistant (standard), and adaptive-intelligent binning; mean (standard) and maximum bin intensity data summation-on the resonance intensities of three different types of metabolites: triglycerides, glucose, and creatinine. The effects were evaluated by correlating the differently preprocessed NMR data with the independently measured metabolite concentrations. The analyses revealed that the standard methods performed inferiorly and that a combination of probabilistic quotient normalization after adaptive-intelligent binning and maximum intensity variable definition yielded the best overall results (triglycerides, R = 0.98; glucose, R = 0.76; creatinine, R = 0.70). Therefore, at least in the case of serum metabolomics, these or equivalent methods should be preferred above the standard preprocessing methods, particularly for univariate analyses. Additional optimization of the normalization procedure might further improve the analyses. [ABSTRACT FROM AUTHOR]

Abstract: Background: A new method (sLDL-EX “SEIKEN”) is commercially available for the direct quantification of small dense LDL-cholesterol (sd-LDL) on automated chemistry analyzers, without manual sample pretreatment. We evaluated the performance of this direct assay to estimate the small dense LDL subclass phenotype (“non-A”), defined by polyacrylamide gel tube electrophoresis. Methods: Fasting serum samples from 189 healthy subjects (age 18–75y, 96 females) were collected. The direct sd-LDL assay (from Randox Laboratories) was applied on a Roche Modular P analyzer. The Quantimetrix LipoprintTM LDL System was used to define LDL subclass phenotypes (A and non-A). ROC curve analysis was performed for sd-LDL and other lipids and apolipoproteins (apo) with respect to phenotype non-A. Results: sd-LDL concentrations (40.4±18.6mg/dl) in the total group correlated (P<0.0001) with apoB (r=0.831), apoB/A-I ratio (r=0.757), non-HDL-cholesterol (r=0.821), triglycerides (r=0.439), and LDL-cholesterol (r=0.641). Higher sd-LDL concentrations (P<0.0001) were measured in subjects with LDL phenotype non-A (53.6±17.0mg/dl, n=92) than in those with phenotype A (27.9±8.9mg/dl, n=97). In logistic regression analysis, sd-LDL and apoA-I were independently associated with LDL subclass phenotype non-A. Highest areas under ROC curves were obtained for sd-LDL (0.943), triglycerides (0.833), triglyceride/HDL-cholesterol (0.838) and apoB/A-I ratio (0.826) to predict phenotype non-A. The sd-LDL cut-off point for optimal sensitivity (87.9%) and specificity (92.8%) was >38.5mg/dl. Conclusions: The direct, homogeneous sd-LDL method is easily applicable on an automated chemistry analyzer and shows acceptable performance to estimate the electrophoretic LDL subclass phenotype. [Copyright &y& Elsevier]

Abstract: Background: An accurate measurement of testosterone is needed in many clinical applications for correct diagnosis and appropriate treatment. Our aim was to develop a fast and robust high-throughput LC-MSMS method for quantification of serum testosterone in women. Methods: Testosterone was derivatized by oximation and extracted with methyl tert-butyl ether from 200 μL of serum. Further matrix elimination was achieved on-line using a column-switching LC-method. The instrumental analysis was performed on an API4000 tandem mass spectrometer equipped with an Agilent series 1312A binary pump and an Agilent series 1311A quaternary pump. The MRM transitions were 304→124 and 304→112 for testosterone and 307→124 and 307→112 for d 3-testosterone. Results: The total analysis time of the column-switching method was 3 min. Linear calibration curves were obtained in the concentration range from 0.035 nmol/L (0.01 μg/L) to 6.92 nmol/L (2 μg/L). Within-day and between-day precision, expressed as the relative standard deviation at four different concentrations ranged from 4.70% to 9.35%. Correlation with the in-house method (solvent–extraction RIA) showed r 2 =0.920. Conclusions: The presented column-switching method offers a simple, fast and economical analysis of testosterone in human serum. The procedure requires only small sample volumes and is well suited for quantification of testosterone in serum from women and children. [Copyright &y& Elsevier]

Abstract: Background: Published methods for routine clinical monitoring of vigabatrin and gabapentin are often very laborious. A simple GC-MS method was developed for the simultaneous quantitative determination of vigabatrin and gabapentin in human serum. Methods: After protein precipitation, the compounds are derivatized by methylation and analysed on a polydimethylsiloxane column using splitless injection. Cyclobarbital is used as the internal standard. To attain maximal sensitivity, detection is performed in selected ion monitoring mode. Results: The method was fully validated and linear calibration curves were obtained in the concentration ranges from 5 to 80 μg/mL for vigabatrin and from 5 to 30 μg/mL for gabapentin. The within-day and day-to-day relative standard deviations at three different concentration levels were &#60;10% and &#60;15%, respectively. The limit of quantitation was 2 μg/mL for both compounds. Conclusions: The presented method provides high chromatographic resolution, good sensitivity and unequivocal identification potential and can be used for simultaneous analysis of both antiepileptics. [Copyright &y& Elsevier]

A high concentration of glycerol in plasma is an interfering factor in the determination of triglycerides, giving rise to (pseudo)hypertriglyceridaemia. Hyperglycerolaemia may be due to the presence of exogenous glycerol or due to endogenous glycerol accumulation. In the present case report, a 57-year-old male patient with end-stage renal disease presented with a pseudohypertriglyceridaemia based on a pronounced hyperglycerolaemia. The hyperglycerolaemia was due to chronic intake of glycerol-containing alcoholic beverages in combination with a reduced glycerol clearance and glycerol kinase activity. In conclusion, an unexplained hypertriglyceridaemia in patients with an impaired renal function should raise the suspicion of hyperglycerolaemia. [ABSTRACT FROM PUBLISHER]

Background: Three adult patients presented with unexpectedly high thyrotropin (TSH) concentrations that were discordant with clinical and biochemical findings of euthyroid or hyperthyroid status. Methods: Antibody interference in the TSH immunoassay (Roche) was investigated by polyethylene glycol (PEG)-pretreatment, heterophilic blocking tube (HBT)-pretreatment, rheumatoid factor (RF) testing, immunofixation, protein A adsorption, and gel filtration chromatography (GFC). Results: PEG-precipitation yielded <20% recovery of serum TSH, whereas HBT-pretreatment did not decrease TSH test results. RF-testing and immunofixation were negative. Protein A adsorption and GFC demonstrated the presence of TSH-immunoglobulin complexes in serum. Conclusions: Interference by TSH-immunoglobulin complexes should be ruled out in euthyroid and hyperthyroid patients presenting with inappropriately increased or non-suppressed TSH values. Clin Chem Lab Med 2009;47:604–6. [ABSTRACT FROM AUTHOR]

Background: Since vitamin C (ascorbic acid, AA) deficiency is common in hemodialysis patients, systematic supplementation has been recommended. Further, vitamin C has been advocated as a potential adjuvant to erythropoietin by virtue of its capacity to improve iron utilization. However, vitamin C may have a paradoxical pro-oxidant effect in the presence of iron. Methods: In 109 hemodialysis patients, oral vitamin C was administered at 360 and 1,500 mg/week during 3 months each, followed by a wash-out period of 3 months. Results: Serum AA increased from 0.22 to 0.33 and 0.63 mg/dl after 360 and 1,500 mg/week, respectively. However, a commensurate increase of plasma malondialdehyde (MDA), a parameter of lipid peroxidation, with 9 and 26% was observed. Serum AA and plasma MDA returned to baseline after withdrawal of vitamin C. Parameters of iron status, nutrition, inflammation, dialysis efficiency and plasma lipids remained unaltered. In a stepwise multiple regression analysis, serum AA and ferritin were strong and independent predictors of MDA. Conclusion: Oral vitamin C supplementation in hemodialysis patients increases lipid peroxidation, especially in patients with increased serum ferritin. The potential benefits of restored vitamin C status and improved erythropoiesis may be entirely overruled by the adverse consequences of oxidative tissue injury. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]