The first aim of the study was to investigate the accuracy and intra-laboratory variation of serum creatinine measurements in clinical laboratories in Flanders. The second purpose was to check the effect of this variation in serum creatinine concentration results on the calculated estimated glomerular filtration rate (eGFR) and the impact on classification of patients into a chronic kidney disease (CKD) stage. 26 routine instruments were included, representing 13 different types of analyzers from 6 manufacturers and covering all current methodologies (Jaffe, compensated Jaffe, enzymatic liquid and dry chemistry methods). Target values of five serum pools (creatinine concentrations ranging from 35 to 934 μmol/L) were assigned by the gold standard method (ID-GC/MS). Intra-run CV (%) (n = 5) and bias (%) from the target values were higher for low creatinine concentrations. Especially Jaffe and enzymatic dry chemistry methods showed a higher error. The calculated eGFR values corresponding with the reported creatinine concentration ranges resulted in a different CKD classification in 47% of cases. Although most creatinine assays claim to be traceable to the gold standard (ID-GC/MS), large inter-assay differences still exist. The inaccuracy in the lower concentration range is of particular concern and may lead to clinical misinterpretation when the creatinine-based eGFR of the patient is used for CKD staging. Further research to improve harmonization between methods is required.

Background: Acute kidney injury (AKI) in critically ill patients is associated with a significant increase in mortality as well as long-term renal dysfunction and chronic kidney disease (CKD). Serum creatinine (SCr), the most widely used biomarker to evaluate kidney function, does not always accurately predict the glomerular filtration rate (GFR), since it is affected by some non-GFR determinants such as muscle mass and recent meat ingestion. Researchers and clinicians have gained interest in cystatin C (CysC), another biomarker of kidney function. The study objective was to compare GFR estimation using SCr and CysC in detecting CKD over a 1-year follow-up after an AKI stage-3 event in the ICU, as well as to analyze the association between eGFR (using SCr and CysC) and mortality after the AKI event. Method: This prospective observational study used the medical records of ICU patients diagnosed with AKI stage 3. SCr and CysC were measured twice during the ICU stay and four times following diagnosis of AKI. The eGFR was calculated using the EKFC equation for SCr and FAS equation for CysC in order to check the prevalence of CKD (defined as eGFR < 60 mL/min/1.73 m²). Results: The study enrolled 101 patients, 36.6% of whom were female, with a median age of 74 years (30–92), and a median length of stay of 14.5 days in intensive care. A significant difference was observed in the estimation of GFR when comparing formulas based on SCrand CysC, resulting in large differences in the prediction of CKD. Three months after the AKI event, eGFR_CysC < 25 mL/min/1.73 m² was a predictive factor of mortality later on; however, this was not the case for eGFR_SCr. Conclusion: The incidence of CKD was highly discrepant with eGFR_CysC versus eGFR_SCr during the follow-up period. CysC detects more CKD events compared to SCr in the follow-up phase and eGFR_CysC is a predictor for mortality in follow-up but not eGFRSCr. Determining the proper marker to estimate GFR in the post-ICU period in AKI stage-3 populations needs further study to improve risk stratification.

To mitigate the massive COVID-19 burden caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), several vaccination campaigns were initiated. We performed a single-center observational trial to monitor the mid- (3 months) and long-term (10 months) adaptive immune response and to document breakthrough infections (BTI) in healthcare workers (n = 84) upon BNT162b2 vaccination in a real-world setting. Firstly, serology was determined through immunoassays. Secondly, antibody functionality was analyzed via in vitro binding inhibition and pseudovirus neutralization and circulating receptor-binding domain (RBD)-specific B cells were assessed. Moreover, the induction of SARS-CoV-2-specific T cells was investigated by an interferon-γ release assay combined with flowcytometric profiling of activated CD4⁺ and CD8⁺ T cells. Within individuals that did not experience BTI (n = 62), vaccine-induced humoral and cellular immune responses were not correlated. Interestingly, waning over time was more pronounced within humoral compared to cellular immunity. In particular, 45 of these 62 subjects no longer displayed functional neutralization against the delta variant of concern (VoC) at long-term follow-up. Noteworthily, we reported a high incidence of symptomatic BTI cases (17.11%) caused by alpha and delta VoCs, although vaccine-induced immunity was only slightly reduced compared to subjects without BTI at mid-term follow-up.

Tinne Monteyne, Ph.D., Matthijs Oyaert, Ph.D., Annelien Van Dalem, Ph.D., Maaike Godefroid , Matthias Cuykx, Ph.D., and Nico Callewaert, Ph.D.. Ann Lab Med 2022;42:566-74. https://doi.org/10.3343/alm.2022.42.5.566

The rapid transportation of blood samples and blood products using drones has high potential in the medical sector. However, before this can be implemented, sufficient evidence that drone transportation is not affecting clinical outcomes is needed. Currently, limited data on the stability of blood, and specifically on platelet activation, after transport using drones are available. Therefore, the impact of drone transportation on platelet activation parameters was analyzed. Blood was drawn from 20 healthy volunteers and lactate dehydrogenase (LDH), potassium, free hemoglobin, PFA-100 closure time, platelet factor 4 (PF4) plasma levels and platelet activation membrane markers were determined in blood that was transported by drone and compared to non-transported samples. In addition, a control group was included where blood samples were transported by car. Transport by both drone and car increased LDH and potassium levels, but the values mostly remained within the total allowable error. Both drone and car transportation impacted platelet activation, as indicated by a small increase in the baseline P-selectin expression and increased PF4 plasma levels. To our knowledge, this is the first study assessing the impact of drone transport on platelet activation. Transportation of blood tubes from healthy individuals using drones has only minimal impacts on blood stability and platelet activation parameters, and is comparable to blood transportation by car. Therefore, the effects observed as a result of drone transportation will likely not impact clinical decision making.