Clinical chemistry and laboratory medicine最新文献

Objectives: Preanalytical phase is an elemental part of laboratory diagnostics, but is prone to humane errors. The aim of this study was to evaluate performance in preanalytical phase external quality assessment (EQA) cases. We also suggest preventive actions for risk mitigation.

Methods: We included 12 EQA rounds (Labquality Ltd.) with three patient cases (36 cases, 54-111 participants, 7-15 countries) published in 2018-2023. We graded performance according to percentage of correct responses in each case as ≥900 % excellent, 70-89 % good, 50-69 % satisfactory, 30-49 % fair and <30 % poor. Performance was simultaneously failed with ≥10 % of responses leading to harmful events.

Results: Overall performance was excellent in 7, good in 12, satisfactory in 10, fair in 4 and poor in 3 cases. Additionally, 7 cases showed failed performance. Routine requests with incorrect sample tubes or incorrect sample handling were detected with good performance. Lower performance was seen with sudden abnormal results, with rare requests, with false patient identification (never-events) and with incorrect test requests. Information technology (IT) solutions (preanalytical checklists, autoverification rules and patient specific notifications) could have prevented 33 of 36 preanalytical errors.

Conclusions: While most common errors were detected with good performance, samples with rare requests or those requiring individualised consideration are vulnerable to human misinterpretation. In many instances, samples with preanalytical errors should have been identified and rejected before reaching the laboratory or being directed to analysis. Optimising IT solutions to effectively detect these preanalytical errors allows for focus on infrequent events demanding accessible professional consultation. EQA preanalytical cases may help in education of correct actions in these occasions.

Objectives: Accurate assessment of calcium levels is crucial for optimal management of regular Haemodialysis (HD) patients. Different calcium adjustment equations and albumin methods; including bromocresol purple (BCP) and bromocresol green (BCG) assays are employed by laboratories, which cause considerable discrepancies between reported results. The aim of this study is to assess the influence of albumin assays on calcium status in stable haemodialysis patients against free calcium (fCa) as a gold standard test.

Methods: A total of 103 paired serum and fCa samples were collected from a cohort of stable HD patients. Albumin levels were measured by either the BCP or BCG method, and samples were also analysed for the total calcium (T.Ca), phosphate, bicarbonate, and pH levels. The performance of BCG-based and BCP-based adjusted calcium equations was compared using Z-scores scatter plots, intraclass correlation coefficient and Cohen Kappa statistic, with fCa being the reference standard.

Results: Unadjusted T.Ca achieved a 70 % overall classification agreement with fCa and identified 61 % of the "true" hypocalcaemic samples. Adjusted calcium concentrations, calculated by either BCP- or BCG-based equation, were poor predictors of fCa; with more than 50 % of the hypocalcaemic samples being misclassified as normocalcaemic. Notably, both equations misclassified the calcium status in 5 (4.9 %) patients with severe hypocalcaemia (i.e., potentially requiring calcium infusion) as mild hypocalcaemia.

Conclusions: Our study showed evidence of hidden hypocalcaemia being missed by the current practice of using adjusted calcium in HD patients. Therefore, we recommend abandoning the adjustment procedure in samples from stable HD patients in favour of fCa measurement.

Objectives: Hemoglobin A_1c (HbA_1c) is an established tool in the diagnosis and follow-up of patients with diabetes. However, in some patients the interpretation of HbA_1c results faces challenges due to additional biological variation or non-steady-state conditions. This study aimed to demonstrate the value of the L-HbA_1c/HbA_1c-ratio as a tool to flag HbA_1c results, which do not reflect average glycemia "as expected" in routine clinical practice.

Methods: A total of 450 samples of unique patients were selected based on the L-HbA_1c/HbA_1c-ratio determined on a Tosoh G8 analyzer resulting in a group with a high ratio (≥0.50), a group with a low ratio (≤0.27) and a group with a normal ratio (0.27-0.50). The relationship between HbA_1c and glycemic markers (fructosamine and random glucose) was established for all ratio groups. In a smaller cohort of type 1 diabetes patients, continuous glucose monitoring was used as glycemic marker.

Results: The correlation between HbA_1c and glycemia (random glucose and fructosamine) differs significantly between the ratio groups. For the same HbA_1c level random glucose levels and protein-corrected fructosamine are higher in the high ratio group compared to the normal and low ratio groups, pointing to an underestimation of the glycemic status by HbA_1c in patients with high L-HbA_1c/HbA_1c-ratios. The sensitivity of a high ratio to predict a glycation gap lower than -1.5 NGSP units is 82 % and the specificity is 65 %.

Conclusions: The results of this study reveal the usefulness of the L-HbA_1c/HbA_1c-ratio as an additional check in the interpretation of HbA_1c results in order to detect HbA_1c results not reflecting glycemia as expected.

Objectives: In the light of a rapidly increasing use of POCT blood gas testing, where tests and interpretation are performed by non-laboratory personnel, the objective was to investigate the knowledge among personnel in the Nordic countries using blood gas analyzers with focus on the interference from hemolysis.

Methods: Information was obtained from a self-developed, pre-tested online questionnaire. The questions covered demographic information about the respondents and specific questions on handling of and knowledge about blood gas analyses and the impact of hemolysis. The questionnaire was distributed by e-mail to relevant colleagues on behalf of the Nordic preanalytical scientific working group under the Nordic Federation of Clinical Chemistry.

Results: A total of 117 respondents completed the questionnaire. 62.7 % respondents both used the analyzer and interpreted the results. 59.6 % respondents did not know to which degree the blood gas analyzer can identify hemolysis. 4.4 % answered that all levels or high levels of hemolysis can be detected. 3.9 % considered the result valid despite hemolysis if it is released from the instrument. 73.7 % of all respondents knew that hemolysis alters potassium measurements, while knowledge about the effect on PaO₂ and bicarbonate measurements were more divergent.

Conclusions: The knowledge about blood gas analyzers with focus on the interference from hemolysis is sparse among non-laboratory personnel using the blood gas analyzers. This emphasizes the need for better education and competence management, which perhaps is even more important for these analyses than for other point-of-care tests.

Objectives: Automated immunoassays for 1,25-dihydroxyvitamin D (1,25(OH)₂D) have increased the use of serum measurements in clinical and research settings, but disagreement with LC-MS/MS methods remains an issue.

Methods: In this study, we examined this problem using samples obtained from healthy young adults, n=80, mean age 21.7 (18-32) years, and a large cohort of paediatric samples, n=422, mean age 7.3 (0-17) years. We compared serum concentrations of 1,25(OH)₂D3/D2 produced by the DiaSorin LIAISON^® XL immunoassay against an LC-MS/MS method with immunoaffinity enrichment and DAPTAD derivation.

Results: Both assays showed intra/inter-assay imprecision of ≤9.4 % across their respective assay range. DEQAS between April 2020 to Jan 2024 (n=80) showed mean bias (SD, 95 %CI) for DiaSorin -0.6 % (6.2, -12.8 to 11.6) and LC-MS/MS of +1.3 % (7.4, -13.3 to 15.8) against their respective method group means. Comparison of measurements in the adult samples showed a strong correlation (r²=0.9331) and concordance (CCC=0.959) between the two methods. LC-MS/MS values were lower than DiaSorin by an overall mean (±SD, 95 %CI) of -1.6 (±14.3, -29.6 to 26.5) pmol/L with an increased negative bias at higher concentrations. In the paediatric samples, weaker correlation (r²=0.6536) and concordance (CCC=0.782) were observed, with greater bias mean (±SD, 95 %CI) of -9.8 (±23.4, -55.7 to 35.9) pmol/L. The variability in the paediatric samples was not associated with concentration or participant age. There was an increase in the correlation and concordance when 1,25(OH)₂D2 was included in the analysis.

Conclusions: It is likely that the metabolites of vitamin D present in the paediatric population contributed to the measurement of 1,25(OH)₂D. The inconsistent agreement highlights the need for better assay harmonisation and paediatric reference intervals using LC-MS/MS method.