Definition and application of performance specifications for measurement uncertainty of 23 common laboratory tests: linking theory to daily practice.

Laboratories should estimate and validate [using analytical performance specifications (APS)] the measurement uncertainty (MU) of performed tests. It is therefore essential to appropriately define APS for MU, but also to provide a perspective on suitability of the practical application of these APS. In this study, 23 commonly ordered measurands were allocated to the models defined during the 2014 EFLM Strategic Conference to derive APS for MU. Then, we checked if the performance of commercial measuring systems used in our laboratory may achieve them. Most measurands (serum alkaline phosphatase, aspartate aminotransferase, creatine kinase, γ-glutamyltransferase, lactate dehydrogenase, pancreatic amylase, total proteins, immunoglobulin G, A, M, magnesium, urate, and prostate-specific antigen, plasma homocysteine, and blood red and white cells) were allocated to the biological variation (BV) model and desirable APS were defined accordingly (2.65%, 4.75%, 7.25%, 4.45%, 2.60%, 3.15%, 1.30%, 2.20%, 2.50%, 2.95%, 1.44%, 4.16%, 3.40%, 3.52%, 1.55%, and 5.65%, respectively). Desirable APS for serum total cholesterol (3.00%) and urine albumin (9.00%) were derived using outcome-based model. Lacking outcome-based information, serum albumin, high-density lipoprotein cholesterol, triglycerides, and blood platelets were temporarily reallocated to BV model, the corresponding desirable APS being 1.25%, 2.84%, 9.90%, and 4.85%, respectively. A mix between the two previous models was employed for serum digoxin, with a 6.00% desirable APS. In daily practice by using our laboratory systems, 16 tests fulfilled desirable and five minimum APS, while two (serum albumin and plasma homocysteine) exceeded goals, needing improvements.

Harmonization Status of Serum Ferritin Measurements and Implications for Use as Marker of Iron-Related Disorders.

BACKGROUND: Serum ferritin is considered a suitable biomarker of iron-related disorders. However, data about the comparability of results among commercial measuring systems (MSs) are contradictory. We performed an intercomparison study aimed at verifying the current interassay variability and its impact on clinical application of the test. Obtaining this information is vital because manufacturers continue to claim calibration alignment to different WHO preparations, which are not related to each other in terms of traceability. METHODS: Four widely used MSs were evaluated. The interassay agreement was verified using 39 human serum pools. The recovery of WHO International Standard (IS) 94/572 (the only reference material available at the time of the study) was evaluated, after assessing the material commutability. Finally, an approach for harmonizing ferritin results was proposed. RESULTS: Highly significant differences (P < 0.00001) among ferritin concentrations assayed by different MSs were detected and the interassay CV (median 22.9%; interquartile range 21.8-25.5) overlapped the desirable intermethod bias (24.6%). IS 94/572 was commutable for use only with Access and Centaur, with Access being the only MS correctly recovering its assigned value. Accordingly, we used regression data against Access to recalibrate MSs, indirectly aligning them to IS 94/572, with a substantial improvement in degree of harmonization and traceability to higher-order reference. CONCLUSIONS: The harmonization among evaluated ferritin MSs is far from optimal, with the implementation of traceability to different WHO ISs being a factor of confusion. A recalibration approach, however, would permit measurement harmonization, allowing the use of common decision thresholds.

A step towards optimal efficiency of HbA1c measurement as a first-line laboratory test: the TOP-HOLE (Towards OPtimal glycoHemOgLobin tEsting) project.

OBJECTIVES: The TOP-HOLE (Towards OPtimal glycoHemOgLobin tEsting) project aimed to validate the HbA1c enzymatic method on the Abbott Alinity c platform and to implement the HbA1c testing process on the total laboratory automation (TLA) system of our institution. METHODS: Three different measuring systems were employed: Architect c4000 stand-alone (s-a), Alinity c s-a, and Alinity c TLA. Eight frozen whole blood samples, IFCC value-assigned, were used for checking trueness. A comparison study testing transferability of HbA1c results from Architect to Alinity was also performed. The alignment of Alinity TLA vs. s-a was verified and the measurement uncertainty (MU) estimated according to ISO 20914:2019. Turnaround time (TAT) and full time equivalent (FTE) were used as efficiency indicators. RESULTS: For HbA1c concentrations covering cut-offs adopted in clinical setting, the bias for both Architect and Alinity s-a was negligible. When compared with Architect, Alinity showed a mean positive bias of 0.54 mmol/mol, corresponding to a mean difference of 0.87%. A perfect alignment of Alinity TLA to the Alinity s-a was shown, and a MU of 1.58% was obtained, widely fulfilling the desirable 3.0% goal. After the full automation of HbA1c testing, 90% of results were released with a maximum TAT of 1 h, 0.30 FTE resource was also saved. CONCLUSIONS: The traceability of Alinity HbA1c enzymatic assay to the IFCC reference system was correctly implemented. We successfully completed the integration of the HbA1c testing on our TLA system, without worsening the optimal analytical performance. The shift of HbA1c testing from s-a mode to TLA significantly decreased TAT.

Pancreatic lipase: why laboratory community does not take enough care of this clinically important test?

Although being the recommended laboratory test to diagnose acute pancreatitis, serum pancreatic lipase (LIP) is among the poorly standardized laboratory tests, and laboratory stakeholders often appear to not take enough care of the quality of its measurements. Here we discuss some important issues that, if not correctly managed and solved, make misdiagnosis of acute pancreatitis by using serum LIP a real possibility. First, the current unavailability of a suitable higher-order reference material to be used as common calibrator should be filled up to definitively improve the inter-method bias. Second, knowledge of the analytical characteristics that may explain the defective performance of LIP assays should be deepened. IVD manufacturers should be more explicit in providing this information, including description of their internal protocol for transferring LIP values from internal references to commercial calibrators. Third, recommended models for accurately estimating measurement uncertainty and reliably defining analytical performance specifications for LIP measurements should be applied. Finally, investments considering alternative options for measuring LIP (e.g., targeted to the development of automated LIP immunoassays) should be warranted. All involved stakeholders (standardization bodies, higher-order reference providers, in vitro diagnostics manufacturers, and laboratory professionals) should contribute to fill the existing gap.

The internal quality control in the traceability era.

To be accurate and equivalent, laboratory results should be traceable to higher-order references. Furthermore, their quality should fulfill acceptable measurement uncertainty (MU) as defined to fit the intended clinical use. With this aim, in vitro diagnostics (IVD) manufacturers should define a calibration hierarchy to assign traceable values to their system calibrators. Medical laboratories should know and verify how manufacturers have implemented the traceability of their calibrators and estimate the corresponding MU on clinical samples. Accordingly, the internal quality control (IQC) program should be redesigned to permit IVD traceability surveillance through the verification by medical laboratories that control materials, provided by the manufacturer as a part of measuring systems, are in the clinically suitable validation range (IQC component I). Separately, laboratories should also monitor the reliability of employed IVD measuring systems through the IQC component II, devoted to estimation of MU due to random effects and to obtaining MU of provided results, in order to apply prompt corrective actions if the performance is worsening when compared to appropriate analytical specifications, thus jeopardizing the clinical validity of test results.

Traceability validation of six enzyme measurements on the Abbott Alinity c analytical system.

Background Laboratory professionals should independently verify the correct implementation of metrological traceability of commercial measuring systems and determine if their performance is fit for purpose. We evaluated the trueness, uncertainty of measurements, and transferability of six clinically important enzyme measurements (alanine aminotransferase [ALT], alkaline phosphatase [ALP], aspartate aminotransferase [AST], creatine kinase [CK], γ-glutamyltransferase [γGT], and lactate dehydrogenase [LDH]) performed on the Abbott Alinity c analytical system. Methods Target values and associated uncertainties were assigned to three pools for each enzyme by using the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference measurement procedures (RMPs) and the pools were then measured on the Alinity system. Bias estimation and regression studies were performed, and the uncertainty associated with Alinity measurements was also estimated, using analytical performance specifications (APS) derived from biological variability of measurands as goals. Finally, to validate the transferability of the obtained results, a comparison study between two Alinity systems located in Milan, Italy, and Bydgoszcz, Poland, was carried out. Results Correct implementation of traceability to the IFCC RMPs and acceptable measurement uncertainty fulfilling desirable (ALP, AST, LDH) or optimal APS (ALT, CK, γGT) was verified for all evaluated enzymes. An optimal alignment between the two Alinity systems located in Milan and Bydgoszcz was also found for all enzyme measurements. Conclusions We confirmed that measurements of ALT, ALP, AST, CK, γGT, and LDH performed on the Alinity c analytical system are correctly standardized to the IFCC reference measurement systems and the system alignment is consistent between different platforms.

Searching for a role of procalcitonin determination in COVID-19: a study on a selected cohort of hospitalized patients.

Objectives: Procalcitonin (PCT) has been proposed for differentiating viral vs. bacterial infections. In COVID-19, some preliminary results have shown that PCT testing could act as a predictor of bacterial co-infection and be a useful marker for assessment of disease severity. Methods: We studied 83 COVID-19 hospitalized patients in whom PCT was specifically ordered by attending physicians. PCT results were evaluated according to the ability to accurately predict bacterial co-infections and death in comparison with other known biomarkers of infection and with major laboratory predictors of COVID-19 severity. Results: Thirty-three (39.8%) patients suffered an in-hospital bacterial co-infection and 44 (53.0%) patients died. In predicting bacterial co-infection, PCT showed a relatively low accuracy (area under receiver-operating characteristic [ROC] curve [AUC]: 0.757; 95% confidence interval [CI]: 0.651-0.845), with a strength for detecting the outcome not significantly different from that of white blood cell count and C-reactive protein (CRP). In predicting patient death, PCT showed an AUC of 0.815 (CI: 0.714-0.892), not better than those of other more common laboratory tests, such as blood lymphocyte percentage (AUC: 0.874, p=0.19), serum lactate dehydrogenase (AUC: 0.860, p=0.47), blood neutrophil count (AUC: 0.845, p=0.59), and serum albumin (AUC: 0.839, p=0.73). Conclusions: Procalcitonin (PCT) testing, even when appropriately ordered, did not provide a significant added value in COVID-19 patients when compared with more consolidated biomarkers of infection and poor clinical outcome. The major application of PCT in COVID-19 is its ability, associated with a negative predictive value >90%, to exclude a bacterial co-infection when a rule-out cut-off (<0.25 µg/L) is applied.

Impact of total automation consolidating first-line laboratory tests on diagnostic blood loss.

Background Blood loss for laboratory testing may contribute to hospital-acquired anemia. When implementing the core laboratory (core-lab) section, we consolidated first-line tests decreasing the number of tubes previously dispatched to different sites. Here, hypothesized benefits of the amount of blood volume drawn were explored. Methods We retrieved, using a laboratory information system (LIS), the number of tubes received by laboratories interested in the change from all clinical wards in a year-based period, i.e. 2013 for pre-core-lab and 2015 for core-lab system, respectively. Data were expressed as the overall number of tubes sent to laboratories, the corresponding blood volume, and the number of laboratory tests performed, normalized for the number of inpatients. Results After consolidation, the average number of blood tubes per inpatient significantly decreased (12.6 vs. 10.7, p < 0.001). However, intensive care units (ICUs) did not reduce the number of tubes per patient, according to the needs of daily monitoring of their clinical status. The average blood volume sent to laboratories did not vary significantly because serum tubes for core-lab required higher volumes for testing up to 55 analytes in the same transaction. Finally, the number of requested tests per patient during the new osystem slightly decreased (-2.6%). Conclusions Total laboratory automation does not automatically mean reducing iatrogenic blood loss. The new system affected the procedure of blood drawing in clinical wards by significantly reducing the number of handled tubes, producing a benefit in terms of costs, labor and time consumption. Except in ICUs, this also slightly promoted some blood saving. ICUs which engage in phlebotomizing patients daily, did not take advantage from the test consolidation.

Heparinate but not serum tubes are susceptible to hemolysis by pneumatic tube transportation.

BACKGROUND: Pneumatic tube transportation (PTT) may induce hemolysis (H) in blood samples. We aimed to compare the H degree before and after PTT implementation in our hospital. METHODS: Hemolysis indices (HI) for all lithium-heparin plasma samples (P) drawn by the Emergency Department in 2-month periods were retrospectively collected and pre- (n=3579) and post-PTT (n=3469) results compared. The impact of PTT introduction was investigated on LDH [HI threshold (HIt), 25], conjugated bilirubin (cBIL) (HIt, 30), K (HIt, 100) and ALT (HIt, 125). In addition, HI retrieved for P and paired serum samples collected in silica clot activator tubes (S) from the same venipuncture were compared in pre- (n=501) and post-PTT (n=509) periods. RESULTS: Median (5-95th percentile) HI in P was significantly higher in post-PTT period [7 (0-112) vs. 6 (0-82), p<0.001]. Results reported as 'Hemolysis' in P increased from 6.6% in pre-PTT to 9.4% in post-PTT (p<0.001). Investigated tests gave the following rejection rates (pre-PTT vs. post-PTT): LDH, 13.4% vs. 18.8%, p<0.001; cBIL, 9.4% vs. 27.0%, p<0.05; K, 3.7% vs. 5.6%, p<0.001; ALT, 2.9% vs. 4.4%, p<0.01. The slightly higher susceptibility to H of S compared to paired P found in the pre-PTT [9 (1-64) vs. 6 (0-85)] was not confirmed in the post-PTT period [7 (0-90) vs. 8 (1-72)], in which median HI in S was significantly lower (p<0.001) than in pre-PTT. CONCLUSIONS: In our setting PTT promotes H in P, increasing the rate of rejected tests. The use of S appears to protect against the hemolysing effect of PTT.

Cystatin C provides a better estimate of the effect of glomerular filtration rate on serum human epididymis protein 4 concentrations.

BACKGROUND: We evaluated the effect of kidney glomerular function on serum concentrations of human epididymis protein 4 (HE4) using creatinine (Cr), cystatin C (CysC) and related chronic kidney disease epidemiology collaboration (CKD-EPI) equations. METHODS: We enrolled 101 women aged ≤56 years with a glomerular filtration rate (GFR) (estimated by CKD-EPI eGFRCr) ranging from 60 to 120 mL/min/1.73 m2, free of any disease and biological and life-style factors known to influence serum HE4 concentrations, and we measured serum Cr, CysC and HE4 concentrations. Cr and CysC values were included in the three CKD-EPI equations to obtain GFR estimates. RESULTS: A statistically significant increase in HE4 median concentrations was detected in subjects with an eGFRCr between 60 and 74 mL/min/1.73 m2 when compared with those with an eGFR >90 mL/min/1.73 m2 (54.2 vs. 42.2 pmol/L, p=0.003). Regression models showed that CysC measurement per se and eGFRCysC were the most sensitive markers to catch HE4 increases due to a mild decrease in renal function [adjusted r2, 0.38 (p=0.00003) and 0.37 (p=0.0004), respectively]. By assuming baseline CysC and eGFRCysC at 0.80 mg/L and 101.5 mL/min/1.73 m2, an increase of 0.10 mg/L in CysC concentrations and a decrease of 10 mL/min of eGFRCysC implied an average (±SE) increase in serum HE4 concentrations of 9.2 (±1.2) and 8.8 (±1.1) pmol/L, respectively. CONCLUSIONS: Our study shows that a better estimate of the effect of GFR on serum HE4 is obtained by measuring CysC in serum or using CKD-EPI eGFRCysC equation.

Hyperuricemia as risk factor for coronary heart disease incidence and mortality in the general population: a systematic review and meta-analysis.

Previous meta-analyses reported no significant or weak association between hyperuricemia (HU) and coronary heart disease (CHD). We updated the literature search, systematically reviewing retrieved papers. The peer-reviewed literature published from 1965 to December 2014 was searched using Medline and Embase. We included prospective cohort studies involving adults (sample size ≥100) with no cardiovascular disease (CVD) and a follow-up of at least 1 year. Studies were excluded if they considered as outcome the CVD incidence/mortality without separately reporting data on CHD, did not adjusted for major confounders and if the 95% confidence interval (CI) for risk ratio (RR) was not available. Relative risk or hazard ratio estimates, with the corresponding CIs, were obtained. For CHD incidence 12 populations were included (457,915 subjects [53.7% males]). For CHD mortality seven populations were included (237,433 subjects [66.3% males]). The overall combined RR were 1.206 (CI 1.066-1.364, p=0.003) for CHD incidence and 1.209 (CI 1.003-1.457, p=0.047) for CHD mortality, respectively. Subgroup analysis showed a marginal (incidence) and not significant (mortality) association between HU and CHD in men, but an increased risk for CHD incidence and mortality in hyperuricemic women (RR 1.446, CI 1.323-1.581, p<0.0001, and RR 1.830, CI 1.066-3.139, p=0.028, respectively). The risk markedly increases for urate concentrations >7.0 mg/dL. HU appears to increase the risk of CHD events in the general population, mainly in adult women. This finding requires, however, further investigation.

Alendronate rescued osteoporotic phenotype in a model of glucocorticoid-induced osteoporosis in adult zebrafish scale.

Long-term effects of glucocorticoid treatment in humans induce bone loss and increase the risk of fracture in the skeleton. The pathogenic mechanisms of glucocorticoid-induced osteoporosis (GIOP) are still unclear. The GIOP and its effects have been reproduced in several animal models including Danio rerio (zebrafish) embryo. The treatment of adult fish with prednisolone (PN) has shown a dose-dependent decrease of mineralized matrix in the scales. Large resorption lacunae are characterized by single TRAP-positive cells which migrate to the margin of the scale merging into a multinucleated structures. The treatment with PN of cultured scales did not increase TRAP activity suggesting that the massive presence of osteoclasts in the resorption sites could be likely the result of a systemic recruitment of monocyte-macrophage precursors. We observed that treatment with PN induced a significant decrease of the alkaline phosphatase (ALP) activity in scale scleroblasts if compared with untreated controls. Then, we investigated the total mineral balance under prednisolone treatment using a time-dependent double live staining. The untreated fish fully repaired the resorption lacuna induced by prednisolone, whereas treated fish failed. The presence of osteoclast resorption fingerprints on new matrix suggested that the osteoclast activity counterbalances the osteodepositive activity exerted by scleroblasts. The treatment with PN in association with alendronate (AL) has surprisingly resulted in a significant decrease of TRAP activity and increase of ALP compared to PN-treated fish in biochemical and histological assays confirming the action of alendronate against GIOP in fish as well in humans.

C-Reactive Protein and Brain Natriuretic Peptides Harmonization.

The harmonization of laboratory biomarkers is pivotal in ensuring consistent and reliable diagnostic outcomes across different clinical settings. This systematic review examines the harmonization of C-Reactive Protein (CRP) and N-Terminal Prohormone of Brain Natriuretic Peptide (NT-proBNP) measurements, both of which are jointly utilized in the diagnosis and management of cardiovascular diseases. To identify relevant studies, we searched the PubMed electronic database using specific medical subject headings and keywords such as C-Reactive Protein, CRP, high sensitivity C-Reactive Protein (hs-CRP), N-terminal pro B-type natriuretic peptide, and NT-proBNP, focusing on publications from June 1 to September 26, 2021. The query filtered studies to include only those in English involving human subjects. From our search, 97 articles met the inclusion criteria and were included for in-depth analysis. Despite their widespread use, significant variability remains in the measurements of CRP and NT-proBNP due to a lack of standardized pre-analytical, analytical, and post-analytical practices. This review highlights the consequences of this variability on clinical decision-making and patient outcomes and emphasizes the need for international standards and guidelines to achieve better harmonization. Our findings advocate for the establishment of universal protocols to enhance the reliability of these biomarker measurements across different clinical environments, ensuring improved healthcare delivery.