Falsely prolonged activated partial thromboplastin time – a pre- and post-analytical issue

This case highlights two common pre-analytical problems identified in routine coagulation testing of activated partial thromboplastin time (aPTT), which were overlooked because of a concurrent flag code indicating no coagulation and the result was replaced by asterisks. It concerns a boy with gastrointestinal bleeding and prolonged aPTT > 300 seconds, which raised the suspicion of haemophilia. When all other coagulation parameters (including specific coagulation factors VIII and IX) turned out to be normal, aPTT was re-measured using another analysis principle, which revealed a normal aPTT. The primary aPTT result turned out to be aborted due to concurrent haemolysis and lipaemia, but was erroneously interpreted as prolonged coagulation. The lesson is awareness of the possibility of numerous flag codes on the same sample overruling each other, and awareness on the responsibility in the post-analytical phase that must be carried by increased educational focus and by the manufacturers

C-reactive protein and albumin kinetics after antibiotic therapy in community-acquired bloodstream infection

Objectives: We assessed C-reactive protein (CRP) and plasma albumin (PA) kinetics to evaluate community-acquired bloodstream infection (CA-BSI) patients’ 1-year outcomes. Methods: Population-based study, with CRP and PA measurements on day 1 (D1) and D4. Relative CRP variations in relation to D1 CRP value were evaluated (CRP-ratio). Patients were classified as fast response, slow response, non-response, and biphasic response. Results: A total of 935 patients were included. At D4, the CRP-ratio was lower in survivors on D365 in comparison with D4–D30 non-survivors and D30–D365 non-survivors (p < 0.001). In comparison with fast response patients, non-response and biphasic response patients had 2.74 and 5.29 increased risk, respectively, of death in D4–D30 and 2.77 and 3.16 increased risk, respectively, of death in D31–D365. PA levels remained roughly unchanged from D1–D4, but lower D1 PA predicted higher short and long-term mortality (p < 0.001). The discriminative performance of the CRP-ratio and D1 PA to identify patients with poor short and long-term mortality after adjustments was acceptable (AUROC = 0.79). Conclusions: Serial CRP measurements at D1 and D4 after CA-BSI is clinically useful to identify patients with poor outcome. Individual patterns of CRP-ratio response with PA at D1 further refine our ability of predicting short or long-term mortality.publishersversionpublishe

Longitudinal trajectory patterns of plasma albumin and C-reactive protein levels around diagnosis, relapse, bacteraemia, and death of acute myeloid leukaemia patients

BACKGROUND: No study has evaluated C-reactive protein (CRP) and plasma albumin (PA) levels longitudinally in patients with acute myeloid leukaemia (AML). METHODS: We studied defined events in 818 adult patients with AML in relation to 60,209 CRP and PA measures. We investigated correlations between CRP and PA levels and daily CRP and PA levels in relation to AML diagnosis, AML relapse, or bacteraemia (all ±30 days), and death (─30-0 days). RESULTS: On the AML diagnosis date (D0), CRP levels increased with higher WHO performance score (PS), e.g. patients with PS 3/4 had 68.1 mg/L higher CRP compared to patients with PS 0, adjusted for relevant covariates. On D0, the PA level declined with increasing PS, e.g. PS 3/4 had 7.54 g/L lower adjusted PA compared to PS 0. CRP and PA levels were inversely correlated for the PA interval 25-55 g/L (R = - 0.51, p < 10-5), but not for ≤24 g/L (R = 0.01, p = 0.57). CRP increases and PA decreases were seen prior to bacteraemia and death, whereas no changes occurred up to AML diagnosis or relapse. CRP increases and PA decreases were also found frequently in individuals, unrelated to a pre-specified event. CONCLUSIONS: PA decrease is an important biomarker for imminent bacteraemia in adult patients with AML.publishersversionpublishe

Impact of C-reactive protein and albumin levels on short, medium, and long term mortality in patients with diffuse large B-cell lymphoma

Objectives and study design: In this population-based study of 602 patients, we amended C-reactive protein (CRP) and plasma albumin (PA) levels around the diagnosis of diffuse large B-cell lymphoma (DLBCL) to the International Prognostic Index (IPI) and assessed 0-90, 91-365, and +365-day survival.Results: The CRP did not contribute to the IPI's prognostic or discriminatory ability, regardless of time period, particularly not in models with PA. In contrast, the PA was an important contributor, especially in the 0-90 day period, but also up to one year after the diagnosis. For day 0-90, the model with the IPI only had an Area Under the Receiver Operating Characteristics (AUROC) of 0.742, whereas the IPI with PA as a continuous variable rendered an AUROC of 0.841. Especially the lower PA quartile (18-32 g/L) contributed to the worse prognosis.Conclusions: The amendment of PA to the IPI may significantly improve the short-term prognostic and discriminative ability.Key messagesThe amendment of the plasma albumin (PA) level to the International Prognostic Index significantly improved the prediction of mortality up to one year after the diagnosis of diffuse large B-cell lymphoma.It was especially the lower quartile of the PA level (18-32 g/L) that contributed to the worse prognosis.publishersversionpublishe

The in vitro effect of antirheumatic drugs on platelet function

Several antirheumatic drugs lower the cardiovascular risk among rheumatoid arthritis patients. It is, however, unknown whether inhibition of platelet function contributes to this risk reduction. Only few studies have investigated the potential role of platelets as a target of antirheumatic drugs. In this study, platelet function was tested in vitro in samples from 24 healthy individuals spiked with antirheumatic drugs in clinically relevant concentrations or vehicle. Platelet aggregation was tested with 96-well light transmission aggregometry (LTA), and when an effect ≥20% compared to vehicle was observed, flow cytometric platelet aggregation and activation were evaluated and closure time was measured by Platelet Function Analyzer (PFA-200). When evaluated by LTA, teriflunomide (the active metabolite of leflunomide), tocilizumab, and prednisolone reduced ADP- and collagen-induced platelet aggregation ≥20%, while adalimumab increased TRAP-induced platelet aggregation ≥20%. Using flow cytometry, agonist-induced platelet aggregation with teriflunomide or vehicle was mean ± standard deviation (SD); 30.7% ± 5.8 vs. 41.7% ± 6.5, p = 0.02 using ADP, and 34.7% ± 13.9 vs. 55.8% ± 3.9, p = 0.01 using collagen. Results indicate that teriflunomide, prednisolone, and tocilizumab inhibit, and adalimumab increases platelet aggregation. The study suggests that the majority of antirheumatic drugs mainly reduced cardiovascular risk through indirect effects (e.g., reducing inflammation)

Light transmission aggregometry using pre-coated microtiter plates and a Victor X5 plate reader.

Light transmission aggregometry (LTA) can be performed with microtiter plates (96-well LTA). When conducting LTA, an agonist is added to platelet-rich plasma and the sample is shaken for minutes after which absorbance readings are done. Platelet aggregation is detected as decrease in absorbance. However, the classical method is cumbersome and therefore microtiter plates can be used for concomitant testing of multiple samples. Furthermore, it would be convenient to prepare the plate in advance of platelet aggregation testing. Aim: The aim of the present study was to establish a simplified 96-well LTA protocol, where plates were pre-coated with agonists and stored at -80 C until use.We developed and validated a protocol for 96-well LTA using a Victor X5 plate reader and pre-coated microtiter plates. The minimum requirement of platelet-rich plasma was 45 μL per sample and the sample platelet count should not be below 100 x109/L. Optimal absorbance reading was 595 nm wavelengths. Platelet aggregation results were higher at 37°C than at room temperature. Platelet adherence to wells after stimulation was observed; it was not avoided by pre-coating of the wells with gelatin. A range of up to 7 concentrations for each agonist (collagen, arachidonic acid, adenosine diphosphate, thrombin receptor-activating peptide and protease-activated receptor-4) was tested concomitantly. A transient rise in platelet aggregation was observed after 2 minutes of shaking in some samples with low agonist concentration, and platelet aggregation was optimal after 10 minutes of shaking for samples with high agonist concentration. Plates could be stored at -80°C for 15 days without significant change in the platelet aggregation results.The 96-well LTA is suitable for platelet aggregation testing and a range of agonist concentrations can be concomitantly tested