Preanalytical Factors Research Articles

CSF Biomarkers in Longitudinal Alzheimer Disease Cohorts: Pre-Analytic Challenges.

The sensitivity of amyloid to pre-analytic factors complicates cerebrospinal fluid (CSF) diagnostics for Alzheimer disease. We report reliability and validity evidence for automated immunoassays from frozen and fresh CSF samples in an ongoing, single-site research program. CSF samples were obtained from 2 Wisconsin cohorts (1256 measurements; 727 participants). Levels of amyloid beta 1-42 (Aβ42), phosphorylated tau 181 (pTau181), and total tau (tTau) were obtained using an Elecsys cobas e 601 platform. Repeatability and fixed effects of storage tube type, extraction method, and freezing were assessed via mixed models. Concordance with amyloid positron emission tomography (PET) was investigated with 238 participants having a temporally proximal PET scan. Repeatability was high with intraclass correlation (ICC) ≥0.9, but tube type strongly affected measurements. Discriminative accuracy for PET amyloid positivity was strong across tube types (area under the curve [AUC]: Aβ42, 0.87; pTau181Aβ42 , 0.96), although optimal thresholds differed. Under real-world conditions, the Elecsys platform had high repeatability. However, strong effects of pre-analytic factors suggest caution in drawing longitudinal inferences.

Concordance between pathologists and between specimen types in detection of HER2-low breast carcinoma by immunohistochemistry

ContextRecent clinical trials indicate that HER2-targeted therapy may benefit HER2-low breast cancer patients including HER2 score 1+ or 2+ and no gene amplification.Concordance between pathologists and between core biopsy and surgical excision in establishing HER2-low status was evaluated. Design57 patients with HER2 negative breast cancer (IHC 0, 1+, or 2+, no gene amplification) by core biopsy were included. Core biopsy and representative tumor from corresponding surgical excision was immunostained for HER2. Original HER2 IHC scores were interpreted using 2018 guidelines. Three pathologists independently interpreted again under 2023 guidelines. Kappa statistic evaluated agreement of HER2 IHC scores. ResultsApplying 2023 guidelines, HER2 IHC scores were concordant among study pathologists in 46 of 57 (81 %) core biopsy and 50 of 57 (88 %) surgical resections. Kappa statistics were 0.78 and 0.85 (substantial agreement), for inter-pathologist agreement of core biopsy and surgical resections under 2023 guidelines; 0.55 (moderate agreement) for agreement between first interpretation by 2018 guidelines and second interpretation by 2023 guidelines; and 0.13 (slight agreement) for agreement in HER2 consensus scores between outside core and surgical resection and 0.49 (moderate agreement) for inside core and surgical resection. Low HER2 expression was found in 28 of 57 (49 %) core biopsy and in 25 of 57 (44 %) surgical excisions. ConclusionsInterobserver agreement among study pathologists was good in core biopsy and surgical excisions, applying updated 2023 guidelines. Intratumoral heterogeneity in protein expression and preanalytical factors may result in variable identification of HER2-low status in core biopsy and surgical excision specimens.

Factors that modulate platelet reactivity as measured by 5 assay platforms in 3429 individuals

BackgroundAssessment of platelet function is key in diagnosing bleeding disorders and evaluating antiplatelet drug efficacy. However, there is a prevailing “one-size-fits-all” approach in the interpretation of measures of platelet reactivity, with arbitrary cutoffs often derived from healthy volunteer responses. ObjectivesOur aim was to compare well-used platelet reactivity assays. MethodsBlood and platelet-rich plasma obtained from the Framingham Heart Study (N = 3429) were assayed using a range of agonists in 5 platelet assays: light transmission aggregometry, Optimul aggregometry, Multiplate impedance aggregometry (Roche Diagnostics), Total Thrombus-Formation Analysis System, and flow cytometry. Using linear mixed-effect models, we determined the contribution of preanalytical and technical factors that modulated platelet reactivity traits. ResultsA strong intra-assay correlation of platelet traits was seen in all assays, particularly Multiplate velocity (r = 0.740; ristocetin vs arachidonic acid). In contrast, only moderate interassay correlations were observed (r = 0.375; adenosine diphosphate Optimul Emax vs light transmission aggregometry large area under the curve). As expected, antiplatelet drugs strongly reduced platelet responses, with aspirin use primarily targeting arachidonic acid–induced aggregation, and explained substantial variance (β = −1.735; P = 4.59 × 10−780; variance proportion = 46.2%) and P2Y12 antagonists blocking adenosine diphosphate responses (β = −1.612; P = 6.75 × 10−27; variance proportion = 2.1%). Notably, female sex and older age were associated with enhanced platelet reactivity. Fasting status and deviations from standard venipuncture practices did not alter platelet reactivity significantly. Finally, the agonist batch, phlebotomist, and assay technician (more so for assays that require additional sample manipulation) had a moderate to large effect on measured platelet reactivity. ConclusionCaution must be exercised when extrapolating findings between assays, and the use of standard ranges must be medication-specific and sex-specific at a minimum. Researchers should also consider preanalytical and technical variables when designing experiments and interpreting platelet reactivity measures.

LC-MS/MS determination of atropine toxicity: Pre-analytical effect of blood collection tube and analytical matrix

Atropine (ATR) intoxication is a recurrent case in emergency departments. The diagnosis is dependent on clinical evaluation and is supported by analytical assessment. The assay is limited by the rapid degradation/metabolism of ATR into TRP as well as the preanalytical factors impairing correct detection and diagnosis.In this study, an HPLC-MS/MS method was optimized for the simultaneous determination of ATR and TRP. The effect of analytical matrix and the impact of blood-collection tube type on the ATR analytical signal were investigated.Separation was achieved using water: 0.01% formic acid acidified methanol (40: 60, v/v) as a mobile phase and Inertsil® C18 column (5 µm; 4.6*150 mm) as a stationary phase. The retention-times were 2.6 and 6.5 min for ATR and TRP, respectively. A chromatographic shift (0.4 min) in ATR peak, but not TRP, was observed in biological samples from neat ones. The best analytical signal was observed when heparinized blood collection tubes were employed. The method was linear, accurate and precise in the ATR toxicity range enabling the detection of ATR intoxication down to a concentration of 0.1 ng/mL by applying a simple sample clean-up procedure.In conclusion, an HPLC-MS/MS method for the simultaneous determination of ATR and TRP is presented. The method highlights the chromatographic shift of ATR peak in biological samples that may induce false-negative detection and poses TRP as an alternative toxicological marker for ATR toxicity. Meanwhile the study recommends heparin tubes for blood-sample collection.

Modeling blood metabolite homeostatic levels reduces sample heterogeneity across cohorts

Blood metabolite levels are affected by numerous factors, including preanalytical factors such as collection methods and geographical sites. These perturbations have caused deleterious consequences for many metabolomics studies and represent a major challenge in the metabolomics field. It is important to understand these factors and develop models to reduce their perturbations. However, to date, the lack of suitable mathematical models for blood metabolite levels under homeostasis has hindered progress. In this study, we develop quantitative models of blood metabolite levels in healthy adults based on multisite sample cohorts that mimic the current challenge. Five cohorts of samples obtained across four geographically distinct sites were investigated, focusing on approximately 50 metabolites that were quantified using 1H NMR spectroscopy. More than one-third of the variation in these metabolite profiles is due to cross-cohort variation. A dramatic reduction in the variation of metabolite levels (90%), especially their site-to-site variation (95%), was achieved by modeling each metabolite using demographic and clinical factors and especially other metabolites, as observed in the top principal components. The results also reveal that several metabolites contribute disproportionately to such variation, which could be explained by their association with biological pathways including biosynthesis and degradation. The study demonstrates an intriguing network effect of metabolites that can be utilized to better define homeostatic metabolite levels, which may have implications for improved health monitoring. As an example of the potential utility of the approach, we show that modeling gender-related metabolic differences retains the interesting variance while reducing unwanted (site-related) variance.

Comparison of standard mismatch repair deficiency and microsatellite instability tests in a large cancer series

BackgroundThe tumor-agnostic indication of immune checkpoint inhibitors to treat cancers with mismatch repair deficiency (dMMR)/microsatellite instability (MSI) increased the demand for such tests beyond Lynch syndrome. International guideline recommendations accept immunohistochemistry (IHC) for dMMR or molecular techniques (PCR or NGS) for MSI status determinations considering the two tests are equal, although there are scattered reports contradicting to this presumption.Materials and methodsHere we have directly compared four protein MMR immunohistochemistry (IHC) to MSI Pentaplex PCR test in a large cancer patient cohort (n = 1306) of our diagnostic center where the two tests have been run parallel in 703 cases.ResultsIn this study we have found a high discrepancy rate (19.3%) of the two tests which was independent of the tumor types. The MSI PCR sensitivity for MMR IHC status was found to be very low resulting in a relatively low positive and negative predicting values. As a consequence, the correlation of the two tests was low (kappa < 0.7). During analysis of the possible contributing factors of this poor performance, we have excluded low tumor percentage of the samples, but identified dMMR phenotypes (classic versus non-classic or unusual) as possible contributors.ConclusionAlthough our cohort did not include samples with identified technical errors, our data strongly support previous reports that unidentified preanalytical factors might have the major influence on the poor performance of the MSI PCR and MMR IHC. Furthermore, the case is open whether the two test types are equally powerful predictive markers of immunotherapies.

Effects of certain pre-analytical factors on the performance of plasma phospho-tau217

IntroductionPre-analytical factors can cause substantial variability in the measurements of cerebrospinal fluid (CSF) and plasma biomarkers of Alzheimer’s disease (AD). However, their effects on the performance of one of the most promising plasma AD biomarkers, phosphorylated tau (p-tau)217, are not known.MethodsWe included 50 amyloid-β positive (Aβ+) and 50 Aβ− participants from the Swedish BioFINDER-1 study. Plasma and CSF p-tau217 were measured using an immunoassay developed by Lilly Research Laboratories. We examined the effect of four plasma handling conditions, i.e., (1) thawing at room temperature (RT) with no centrifugation, (2) thawing at RT followed by centrifugation, (3) thawing on ice with no centrifugation, and (4) thawing on ice followed by centrifugation. In addition, we also tested the effects of up to 3 freeze–thaw cycles on the associations of plasma p-tau217 with AD-related pathologies measured with CSF p-tau217 and CSF Aβ42/Aβ40.ResultsIn the whole cohort (combining Aβ+ and Aβ− participants), we found significant correlations between plasma p-tau217 and both CSF p-tau217 (Rrange, 0.614–0.717, p < 0.001) and CSF Aβ42/Aβ40 (Spearman Rrange, − 0.515 to − 0.652, p < 0.001) for each of the four tested conditions. Correlations between plasma and CSF p-tau217 were also significant for all conditions in the Aβ+ group (Rrange, 0.506–0.579, p < 0.001). However, in this Aβ+ subgroup, correlations with CSF Aβ42/Aβ40 were only significant for centrifuged samples (thawed at RT, R = − 0.394, p = 0.010; thawed on ice, R = − 0.406; p = 0.007). In Aβ− participants, correlations between plasma and CSF p-tau217 were again significant only for centrifuged samples (thawed at RT, R = 0.394, p = 0.007; thawed on ice, R = 0.334; p = 0.022), with no correlations seen between plasma p-tau217 and CSF Aβ42/Aβ40 for any of the conditions. While the accuracy of plasma p-tau217 to identify individuals with abnormal CSF Aβ42/Aβ40 or CSF p-tau217 status was high, the AUCs for samples thawed at RT and analyzed without centrifugation were numerically lower than the AUCs of other conditions (CSF Aβ42/Aβ40 = 0.845 vs 0.872–0.884; CSF p-tau217 = 0.866 vs 0.908–0.924, pdiff > 0.11). P-tau217 concentration was consistently higher in non-centrifuged samples than in centrifuged samples (p ≤ 0.021). There were no differences between samples freeze-thawed once, twice, or three times.ConclusionCentrifugation improved the performance of plasma p-tau217, but thawing temperatures and up to three freeze–thaw cycles did not have a significant impact. These results may inform the future development of standardized sample-handling protocols for AD biomarkers.

Analysis of the Differences between Bethesda Groups according to Conventional Smear and Liquid-Based Cytology Methods in Cervicovaginal Cytology: A Single-Center Experience with 165,915 Cases

Introduction: Liquid-based cytology (LBC) has replaced conventional smear (CS) in the world. In this study, through a series with a large number of cases, we aimed to make a comparison and general evaluation in all groups, primarily epithelial abnormalities, according to LBC and CS methods. This study was carried out in a private pathology laboratory located in a metropolitan city, where cytological materials sent from many clinics were examined. Material and Methods: There were 165,915 cases whose smears were examined between 2012 and 2020, most of them conventional (131,224 CS, 34,691 LBC). Cases were evaluated on the basis of the Bethesda 2014 classification and divided into sub-diagnostic categories after they were divided into two main groups as “with epithelial abnormalities” and “without.” χ2 and Fischer’s precision statistical tests were conducted using SPSS 23.0 package. In the CS process, cervical samples were obtained using an endocervical brush and a spatula. Cells were directly spread onto the slides and promptly fixed in 95% ethanol, followed by staining with the standard Papanicolaou stain. For LBC ThinPrep, cervical specimens were gathered using a cervix brush. The brush was washed in a vial and discarded. Finally, cells were isolated through vacuum filtration and transferred to the slide using air pressure. Results: Squamous cell abnormalities (atypical squamous cells of undetermined significance [ASC-US], atypical squamous cells – cannot exclude high-grade squamous intraepithelial lesion [ASC-H], low-grade squamous intraepithelial lesion [LSIL], high-grade squamous intraepithelial lesion [HSIL], squamous cell carcinoma, atypical glandular cells of undetermined significance) were reported in 5,696 (3.43%) cases. ASC (ASC-US + ASC-H)/SIL ratio (1.36/2.04) was found to be 0.67 (recommended Bethesda ratio is <3). ASC-US (p < 0.001), ASC-H (p < 0.001), and HSIL(p < 0.001) detection rate of LBC was found to be significantly higher than CS. ASC-US (1.8/1.2), ASC-H (0.08/0.008), and HSIL (0.6/0.3) case ratios of LBC/CS were found to be significantly higher in LBC. LSIL (1.72/1.66) rate was similar. Conclusion: LBC is superior to CS in detecting epithelial lesions. In addition to being used as a screening method, it is clear that it makes a great contribution to reducing cervical carcinomas due to HPV typing. Definitive comments regarding comparison of methods on reactive changes and microorganism detection are challenging. Preanalytical factors might account for these situations.

Algorithm-assisted diagnosis of Hirschsprung’s disease – evaluation of robustness and comparative image analysis on data from various labs and slide scanners

BackgroundDifferences in the preparation, staining and scanning of digital pathology slides create significant pre-analytic variability. Algorithm-assisted tools must be able to contend with this variability in order to be applicable in clinical practice. In a previous study, a decision support algorithm was developed to assist in the diagnosis of Hirschsprung's disease. In the current study, we tested the robustness of this algorithm while assessing for pre-analytic factors which may affect its performance.MethodsThe decision support algorithm was used on digital pathology slides obtained from four different medical centers (A-D) and scanned by three different scanner models (by Philips, Hamamatsu and 3DHISTECH). A total of 192 cases and 1782 slides were used in this study. RGB histograms were constructed to compare images from the various medical centers and scanner models and highlight the differences in color and contrast.ResultsThe algorithm was able to correctly identify ganglion cells in 99.2% of cases, from all medical centers (All scanned by the Philips slide scanner) as well as 95.5% and 100% of the slides scanned by the 3DHISTECH and Hamamatsu brand slide scanners, respectively. The total error rate for center D was lower than the other medical centers (3.9% vs 7.1%, 10.8% and 6% for centers A-C, respectively), the vast majority of errors being false positives (3.45% vs 0.45% false negatives). The other medical centers showed a higher rate of false negatives in relation to false positives (6.81% vs 0.29%, 9.8% vs 1.2% and 5.37% vs 0.63% for centers A-C, respectively). The total error rates for the Philips, Hamamatsu and 3DHISTECH brand scanners were 3.9%, 3.2% and 9.8%, respectively. RGB histograms demonstrated significant differences in pixel value distribution between the four medical centers, as well as between the 3DHISTECH brand scanner when compared to the Philips and Hamamatsu brand scanners.ConclusionsThe results reported in this paper suggest that the algorithm-based decision support system has sufficient robustness to be applicable for clinical practice. In addition, the novel method used in its development – Hierarchial-Contexual Analysis (HCA) may be applicable to the development of algorithm-assisted tools in other diseases, for which available datasets are limited. Validation of any given algorithm-assisted support system should nonetheless include data from as many medical centers and scanner models as possible.

Pre-analytical diagnostic differences despite high adherence to guidelines for gestational diabetes mellitus

Regional variations in the prevalence of gestational diabetes mellitus (GDM) have been found across Denmark. The objectives of this exploratory survey were to evaluate adherence to the national guideline for screening and diagnosing GDM and to identify variations in pre-analytical or analytical factors, which could potentially contribute to variations in GDM prevalence across regions. In a national interview-based survey, obstetric departments and laboratories throughout Denmark handling GDM screening or diagnostic testing were invited to participate. Survey questionnaires were completed through personal interviews. In total, 21 of 22 identified obstetric departments and 44 of 45 identified laboratories participated. Adherence to guideline among obstetric departments ranged 67–100% and uniformity in laboratory procedures was high. However, the gestational age at the time of late diagnostic testing with oral glucose tolerance test (OGTT) varied considerably, with 48% (10/21) of departments testing outside the recommended 24–28 weeks’ gestation. Procedural heterogeneity was most pronounced for the parts not described in current guidelines, with choice of laboratory equipment being the most diverse factor ranging 3–39% nationally. In conclusion, the overall adherence to the national guidelines was high across regions, and obstetric departments and laboratories had high uniformity in the procedures for screening and diagnosing GDM. Uniformity was generally high for procedures included in the guideline and low if not included. However, a high proportion of GDM testing was performed outside the recommended gestational window in late pregnancy, which may be a pre-analytical contributor to regional differences in GDM prevalence.

Pre-Analytical Factors Affecting Extracellular DNA in Saliva

Salivary DNA is widely used for genetic analyses because of its easy collection. However, its extracellular fraction in particular, similar to the extracellular DNA (ecDNA) in plasma, could be a promising biomarker for oral or systemic diseases. In contrast to genetics, the quantity of salivary ecDNA is of importance and can be affected by the pre-analytical processing of samples, but the details are not known. The aim of our study was to analyze the effects of centrifugation and freezing of saliva on the concentration of ecDNA in saliva. Fifteen healthy volunteers, free of any known systemic or oral diseases, were asked to collect unstimulated saliva samples. Aliquots were centrifuged at 1600× g and frozen or directly processed. The fresh or thawed cell-free saliva samples underwent subsequent centrifugation at 16,000× g. The supernatants were used for DNA isolation and quantification using fluorometry and real-time PCR. While freezing had minimal effects on the salivary ecDNA concentration, another centrifugation step decreased ecDNA considerably in both fresh and frozen samples (by 97.8% and 98.4%, respectively). This was mirrored in the quantitative PCR targeting a nuclear (decrease by 93.5%) and mitochondrial (decrease by 97.7%) ecDNA sequence. In conclusion, in this first study focusing on the technical aspects of salivary ecDNA quantitation, we show that, regardless of its subcellular origin, the concentration of ecDNA in saliva is mainly affected by additional centrifugation and not by the freezing of centrifuged cell-free saliva samples. This suggests that most salivary ecDNA likely is associated with cell debris and apoptotic bodies. Which fraction is affected by a particular disease should be the focus of further targeted studies.

Immunohistochemistry screening for TP53 mutation in myeloid neoplasms in AZF-fixed bone marrow biopsies

TP53 mutational status in myeloid neoplasms is prognostic and in acute myeloid leukaemia (AML) may lead to alternative induction therapy; therefore, rapid assessment is necessary for precision treatment. Assessment of multiple prognostic genes by next generation sequencing in AML is standard of care, but the turn-around time often cannot support rapid clinical decision making. Studies in haematological neoplasms suggest p53 immunohistochemistry (IHC) correlates with TP53 mutational status, but they have used variable criteria to define TP53 overexpression. p53 IHC was performed and interpreted on AZF-fixed, acid decalcified bone marrow biopsies on 47 cases of clonal myeloid neoplasms with TP53 mutations between 2016 and 2019 and 16 control samples. Results were scored by manual and digital analysis. Most TP53-mutated cases (81%) overexpressed p53 by digital analysis and manual analysis gave similar results. Among the nine TP53-mutated IHC-negative cases, seven (78%) were truncating mutations and two (22%) were single-hit missense mutations. Using a digital cut-off of at least 3% ≥1+ positive nuclei, the sensitivity and specificity are 81% and 100%; cases with loss-of-function mutations were more likely to be negative. In this cohort, p53 immunopositivity correlated with TP53 mutational status, especially missense mutations, with excellent specificity. Truncating TP53 mutations explain most IHC-negative cases, impacting the sensitivity. We demonstrate that p53 IHC can screen for TP53 mutations allowing quicker treatment decisions for most patients. However, not all patients will be identified, so molecular studies are required. Furthermore, cut-offs for positivity vary in the literature, consequently laboratories should independently validate their processes before adopting p53 IHC for clinical use. p53 IHC performs well to screen for TP53 mutations in AZF-fixed bone marrow. Performance in our setting differs from the literature, which shows variability of pre-analytic factors and cut-offs used to screen for TP53 mutations. Each laboratory should validate p53 IHC to screen for TP53 mutations in their unique setting.

Optimized protocol for quantification of extracellular nicotinamide adenine dinucleotide: evaluating clinical parameters and pre-analytical factors for translational research.

Nicotinamide adenine dinucleotide (NAD+), a coenzyme for more than 500 enzymes, plays a central role in energy production, metabolism, cellular signaling, and DNA repair. Until recently, NAD+ was primarily considered to be an intracellular molecule (iNAD+), however, its extracellular species (eNAD+) has recently been discovered and has since been associated with a multitude of pathological conditions. Therefore, accurate quantification of eNAD+ in bodily fluids such as plasma is paramount to answer important research questions. In order to create a clinically meaningful and reliable quantitation method, we analyzed the relationship of cell lysis, routine clinical laboratory parameters, blood collection techniques, and pre-analytical processing steps with measured plasma eNAD+ concentrations. Initially, NAD+ levels were assessed both intracellularly and extracellularly. Intriguingly, the concentration of eNAD+ in plasma was found to be approximately 500 times lower than iNAD+ in peripheral blood mononuclear cells (0.253 ± 0.02 μM vs. 131.8 ± 27.4 μM, p = 0.007, respectively). This stark contrast suggests that cellular damage or cell lysis could potentially affect the levels of eNAD+ in plasma. However, systemic lactate dehydrogenase in patient plasma, a marker of cell damage, did not significantly correlate with eNAD+ (n = 33; r = -0.397; p = 0.102). Furthermore, eNAD+ was negatively correlated with increasing c-reactive protein (CRP, n = 33; r = -0.451; p = 0.020), while eNAD+ was positively correlated with increasing hemoglobin (n = 33; r = 0.482; p = 0.005). Next, variations in blood drawing, sample handling and pre-analytical processes were examined. Sample storage durations at 4°C (0-120 min), temperature (0° to 25°C), cannula sizes for blood collection and tourniquet times (0 - 120 s) had no statistically significant effect on eNAD+ (p > 0.05). On the other hand, prolonged centrifugation (> 5 min) and a faster braking mode of the centrifuge rotor (< 4 min) resulted in a significant decrease in eNAD+ levels (p < 0.05). Taken together, CRP and hemoglobin appeared to be mildly correlated with eNAD+ levels whereas cell damage was not correlated significantly to eNAD+ levels. The blood drawing trial did not show any influence on eNAD+, in contrast, the preanalytical steps need to be standardized for accurate eNAD+ measurement. This work paves the way towards robust eNAD+ measurements, for use in future clinical and translational research, and provides an optimized hands-on protocol for reliable eNAD+ quantification in plasma.

QComics: Recommendations and Guidelines for Robust, Easily Implementable and Reportable Quality Control of Metabolomics Data.

The implementation of quality control strategies is crucial to ensure the reproducibility, accuracy, and meaningfulness of metabolomics data. However, this pivotal step is often overlooked within the metabolomics workflow and frequently relies on the use of nonstandardized and poorly reported protocols. To address current limitations in this respect, we have developed QComics, a robust, easily implementable and reportable method for monitoring and controlling data quality. The protocol operates in various sequential steps aimed to (i) correct for background noise and carryover, (ii) detect signal drifts and "out-of-control" observations, (iii) deal with missing data, (iv) remove outliers, (v) monitor quality markers to identify samples affected by improper collection, preprocessing, or storage, and (vi) assess overall data quality in terms of precision and accuracy. Notably, this tool considers important issues often neglected along quality control, such as the need of separately handling missing values and truly absent data to avoid losing relevant biological information, as well as the large impact that preanalytical factors may elicit on metabolomics results. Altogether, the guidelines compiled in QComics might contribute to establishing gold standard recommendations and best practices for quality control within the metabolomics community.

Research on the stability changes in expert consensus of the ACTH detection preprocessing scheme

Abstract Objectives Adrenocorticotropic hormone (ACTH) is extremely unstable and can easily degrade at room temperature. The experts agreed that the samples should be transported in an ice bath. If it cannot be detected immediately, the plasma should be separated and frozen, which is difficult to carry out in routine practice. This study was performed to explore the preanalytical factors that influence the stability of adrenocorticotrophic hormone (ACTH) measurements. Methods ACTH levels in 21 EDTA whole-blood samples were measured immediately after 0 h and then divided into three equal groups according to the corresponding values (low, L; median, M; and high, H). Next, three sample processing methods (including seven subtypes) were used: whole blood was uncentrifuged (named the A method), stored at 4 °C or 22 °C, centrifuged but not subjected to plasma removal (the B method), stored at 4 °C or 22 °C, and centrifuged with the plasma removed and stored (the C method) at 4 °C, 22 °C, and −20 °C. Each subtype contained three samples, namely, L, M, and H; these samples were retested using a Siemens XP2000 at different times. The change bias was calculated at 0 h. Results Compared to that at 0 h, there was no significant change in ACTH up to 24 h when the sample was stored at 4 °C or 22 °C with the B method (p&gt;0.05), while it significantly changed (up or down &gt;10 %) at 4 °C/24 h (bias is expressed as the mean±SEM; 13.37±21 %, p&lt;0.05) and 22 °C/12 h (9.13±7.68 %, p&lt;0.05) with the A method; and 4 °C/24 h (8.93±5.54 %, p&lt;0.05), 22 °C/12 h (9.5±4.47 %, p&lt;0.05) and −20 °C/3 h (12.03±4.8 %, p&lt;0.05) with the C method. Conclusions After ACTH samples were centrifuged, the presence of plasma without removal did not affect the detection value, and the sample was stored at 4 °C for up to 24 h. There was a significant difference in the detection of ATCH when the sample was stored at −20 °C and thawed again (p&lt;0.05).

Critical Factors in Sample Collection and Preparation for Clinical Metabolomics of Underexplored Biological Specimens.

This review article compiles critical pre-analytical factors for sample collection and extraction of eight uncommon or underexplored biological specimens (human breast milk, ocular fluids, sebum, seminal plasma, sweat, hair, saliva, and cerebrospinal fluid) under the perspective of clinical metabolomics. These samples are interesting for metabolomics studies as they reflect the status of living organisms and can be applied for diagnostic purposes and biomarker discovery. Pre-collection and collection procedures are critical, requiring protocols to be standardized to avoid contamination and bias. Such procedures must consider cleaning the collection area, sample stimulation, diet, and food and drug intake, among other factors that impact the lack of homogeneity of the sample group. Precipitation of proteins and removal of salts and cell debris are the most used sample preparation procedures. This review intends to provide a global view of the practical aspects that most impact results, serving as a starting point for the designing of metabolomic experiments.

Study of serum calprotectin level in rheumatoid arthritis: unexpected low level and possible explanations

BackgroundAssessment of disease activity in rheumatoid arthritis (RA) is crucial to optimize the response to treatment and prevent radiographic progression. DAS28 is the most commonly used disease activity index, which incorporates either erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). Several studies showed that using ESR and/or CRP in assessing disease activity falls short of detecting a significant portion of patients with active disease. Calprotectin (CLP) is an interesting protein that was found to be a promising biomarker of disease activity in RA patients’ sera when CRP is normal. This study aimed to measure serum CLP level in 50 RA patients with different grades of disease activity and compare its level with age- and sex-matched control.ResultsIn this case–control study, the mean serum CLP level was significantly lower in RA patients (25.94 ± 25.87 ng/ml) compared to the control group values (53.02 ± 77.93 ng/ml), p < 0.001. The measured serum CLP in RA patients was lower than its level in other published studies. No significant difference was found between patients with different disease activity grades in the serum CLP level (H = 4.28, p = 0.23). Serum samples were collected and stored from RA patients over 4 months and from the control subjects over 1.5 months and were stored at –80 °C until analysis was performed according to the manufacturer’s instruction.ConclusionThe low level of serum CLP among RA patients is most probably due to proteolysis related to storage conditions. Pre-analytic factors like the type of blood sample, whether the sample is fresh or frozen, and duration of storage exert an effect on serum CLP level when measured by enzyme-linked immunosorbent assay.

Process improvement in automated blood cultures: Our road to better patient care

BackgroundBlood cultures (BC) are a complex multistep process susceptible to errors at multiple levels. Our study was conducted to monitor the compliance to standard operating procedures, design an intervention plan for improvement and monitor the impact of the intervention. The study design focuses on the intervention. MethodsA hospital-based prospective interventional study was carried out, monitoring various pre-analytical, analytical, and post-analytical factors in two phases. Our interventions focused on communication and training for the deficiencies noted in completeness of test request form, contamination rates, and sample loading interval. ResultsComparison between both phases showed a statistically significant improvement (p < 0.05, Chi square test) following our interventions in the completeness of test request form, contamination rates and sample loading interval. There was an improvement in the intimation of critical Gram stain from positive flagged bottles, which was not statistically significant. ConclusionOur study highlights how educational interventions can influence quality of BC. Continuous monitoring and interventions are key for quality improvement in BC processes.

Evaluation of the influence of pre-analytical factors on serum iron levels, total iron binding capacity, transferrin saturation index and ferritin

Evaluation of the influence of pre-analytical factors on serum iron levels, total iron binding capacity, transferrin saturation index and ferritin

Pre-analytical Factors Influencing Blood Sample Rejection Rate in the Hematology Laboratory of the Philippine General Hospital from 2018 to 2022: A Cross-sectional Study

Pre-analytical Factors Influencing Blood Sample Rejection Rate in the Hematology Laboratory of the Philippine General Hospital from 2018 to 2022: A Cross-sectional Study