Band 47, Heft 3

Objectives Differences between capillary and venous glucose concentrations have been reported in the past. In continuous glucose monitoring (CGM) system performance studies, comparator measurements are often performed in venous samples, despite CGM systems typically aiming at providing capillary-like values. In this study, differences between venous, capillary and interstitial glucose concentrations, measured with a laboratory analyzer, a self-monitoring of blood glucose (SMBG) system and an intermittent-scanning CGM system were investigated in subjects without diabetes after glucose load. Methods During the study, an oral glucose tolerance test (oGTT) was performed with 41 participants who had no known history of diabetes (mean age 25.5 ± 9.7 years). Venous blood samples for measurement with a laboratory analyzer were collected before drinking the standardized 75 g glucose solution and after 60 and 120 min. In parallel, capillary blood was obtained for measurement with a laboratory analyzer and an SMBG system, and interstitial glucose values were measured with an intermittent-scanning CGM system. Results Glucose concentrations in the fasting state were slightly different for the three different compartments whereas considerable differences (some median differences exceeding 30 %) in glucose concentration were observed 60 and 120 min after the start of the oGTT. Conclusions Marked differences with a high inter-individual variability between venous, capillary, and interstitial fluid glucose concentrations were found especially after glucose load. These differences can affect perceived CGM accuracy in performance studies depending on the specific comparator method used, and they are potentially relevant in clinical practice, like diabetes diagnosis.

Objectives To better characterize occurrence and extent of anticoagulant-associated pseudothrombocytopenia (PTCP) in the daily routine of a high-throughput clinical laboratory in order to draw conclusions on a more precise definition of this phenomenon. Methods Concomitant platelet counts in both EDTA and citrate whole blood (WB) performed in our laboratory over a period of four years and 9 months, were analyzed, calculating the correlation, as well as the absolute difference in the results obtained from both materials, cross-referencing these measures with automated flags for platelet aggregates and the results of the visual examination for platelet aggregates of peripheral blood smears. Results Platelet counts in both materials were strongly correlated (ρ=0.86; p<0.0001) but are on average significantly higher in EDTA WB than in citrate WB (median difference: 11 ± 14.8/nL, p<0.0001). This is in spite of numerous instances of EDTA-associated PTCP recorded in our data, where the opposite is the case. The automated flag for possible platelet aggregates was shown to be very unspecific, while a machine-learning algorithm suggested the difference in platelet counts between EDTA and citrate WB as a predictor of platelet aggregates. Conclusions EDTA-associated PTCP is a regular occurrence. Differences in platelet counts between EDTA and citrate WB appear to be a far better predictor of PTCP than automated flags. A clear and useful definition of PTCP is still missing, however, and cannot be derived from our data either, indicating the need for further research.

Objectives To explore the predictive value of C-reactive protein (CRP)-to-albumin (ALB) ratio (CAR) for the risk of 28-day mortality in patients with severe pneumonia. Methods A total of 152 patients with severe pneumonia treated from January 2020 to January 2022 were enrolled and assigned into survival group (n=107) and death group (n=45) according to their survival status after treatment for 28 d. Their clinical data were compared, and the influencing factors for 28-day mortality were explored by multiple logistic regression analysis. The receiver operating characteristic (ROC) curve was plotted to assess the value of CAR for predicting 28-day mortality risk. A risk prediction model was constructed, and its prediction efficiency was evaluated. Results The death group had significantly older age, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Murray Lung Injury Score, Sequential Organ Failure Assessment score, white blood cell count, neutrophil count, red cell volume distribution width, neutrophil-to-lymphocyte ratio (NLR), fibrinogen, procalcitonin, blood lactic acid (Lac), CRP and CAR and significantly lower oxygenation index and ALB than those of the survival group (p<0.05). APACHE II score, NLR, Lac and CAR were independent risk factors for 28-day mortality (p<0.05). AUC of the established prediction model was 0.826, with sensitivity of 88.45 % and specificity of 87.32 %, indicating high discrimination. The nomogram model had clinical value when the risk threshold probability was 11–93 %. Conclusions CAR is an independent risk factor that shows a high predictive value for the 28-day mortality risk in patients with severe pneumonia.

Objectives Interleukin 21 (IL-21) is a receptor participating in innate immunity and correlates with the activation of innate immune cells. We sought to investigate the role of plasma IL-21 in patients with idiopathic membranous nephropathy (IMN). Methods This was a cross-sectional and case-control study. We analyzed plasma IL-21 in patients with IMN, with other kidney diseases as the diseased controls (DCs), and the healthy controls (HCs), regarding their associations with the risk of having IMN and IMN severity. Results We enrolled 132, 22, and 38 patients with IMN, DC, and HC, respectively. Plasma IL-21 was significantly higher in those with IMN [9.42 (6.93, 12.60)] and DC [7.84 (2.90, 7.95)] compared with HC [5.60 (2.90, 7.10)] (p < 0.05). Plasma IL-21 was significantly higher in those with IMN stage III [10.36 (6.94, 20.88)] and II [9.75 (7.60, 14.27)] than those with IMN stage I [6.99 (3.91, 9.08)] (p < 0.05). Plasma IL-21 was significantly higher in those with a positive anti-phospholipase A2 receptor antibody (PLA2R) [9.60 (8.27, 12.93)] than those with a negative anti-PLA2R antibody [4.84 (2.90, 11.28)] (p < 0.05). Receiver operator characteristic curve analysis showed that a cutoff value of 7.665 pg/mL distinguished patients with IMN from HC and DC with a sensitivity and specificity of 68.94 and 89.47 %, respectively, and the area under the curve was 0.8184. A cutoff value of 7.830 pg/mL identified those with IMN stage II with a sensitivity and specificity of 74.03 and 89.47 %, respectively, with an area under the curve of 0.8718 (p<0.001). Multivariate regression showed that plasma IL-21 was positively correlated with anti-PLA2R and 24 h urine protein, and negatively correlated with total protein and serum albumin. Conclusions Plasma IL-21 levels increased significantly in patients with IMN. IL-21 may therefore serve as a biomarker for IMN.

Objectives We evaluated analytical performance, functionality, reliability, and comparability of cobas ® pure integrated solutions (Roche Diagnostics) under routine-like conditions. Methods The study was conducted in Europe and Asia (five sites). Seventy-six applications covering ion selective electrolytes (ISE), clinical chemistry (CC), and immunochemistry (IC) analytes were assessed using Elecsys ® immunochemistry assays (Roche Diagnostics). Samples included control material and pseudonymized residual samples (plasma/serum/urine). Analytical performance, functionality, and system reliability were evaluated. An inter-laboratory survey, routine simulation imprecision (RSI) and method comparison experiments, and dedicated workflow runs were conducted. Results Most coefficients of variation (CVs) for repeatability were <1 % for ISE, ≤2 % for CC, and <2.5 % for IC assays; for intermediate precision were ≤2 % for ISE and CC, and <2.5 % for IC assays; and for reproducibility were ≤3 % for ISE and CC, and <2.5 % for IC assays. Most RSI reference (94 %) and random part (93 %) CVs were ≤2 %; 99 % of runs completed without system-related interruption. 218 method comparisons generated median Passing–Bablok slope of 1.00, median bias at the medical decision point of −0.1 %, and median Pearson’s r of 0.998. Conclusions cobas pure integrated solutions demonstrated precise and accurate results under routine-like conditions and comparable results vs. commercial analyzers, supporting implementation into routine practice.