Is it acceptable to use coagulation plasma samples stored at room temperature and 4°C for 24 hours for additional prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, and D-dimer testing?

INTRODUCTION: Coagulation laboratories are faced on daily basis with requests for additional testing in already analyzed fresh plasma samples. This prompted us to examine whether plasma samples stored at room temperature (RT), and 4°C for 24 hours can be accepted for additional prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen (Fbg), antithrombin (AT), and D-dimer testing. METHODS: We measured PT, aPTT, Fbg in 50 and AT in 30 plasma samples with normal and pathological values, within 4 hours of blood collection (baseline results) and after 24-hours storage at RT (primary tubes), and 4°C (aliquots). D-dimer stability was investigated in 20 samples stored in primary tubes at 4°C. RESULTS: No statistically significant difference between baseline results and results in samples stored at RT and 4°C was observed for PT (P=.938), aPTT (P=.186), Fbg (P=.962), AT (P=.713), and D-dimers (P=.169). The highest median percentage changes were found for aPTT, being more pronounced for samples stored at 4°C (13.0%) than at RT (8.7%). CONCLUSION: Plasma samples stored both at RT and 4°C for 24 hours are acceptable for additional PT, Fbg, and AT testing. Plasma samples stored 24 hours in primary tubes at 4°C are suitable for D-dimer testing.

New quantitative aPTT waveform analysis and its application in laboratory management of haemophilia A patients.

Diagnosis of haemophilia A is usually made by the measurement of factor VIII (FVIII) activity that allows categorization of the disease severity. However, tests that assess global haemostasis may better reflect clinical features and give additional clinically relevant information. The aim of this study was to develop a new quantitative activated partial thromboplastin time (aPTT) waveform analysis and compare it with FVIII activities to find out whether waveform parameters are superior determinants of clinical phenotype. A total of 81 haemophilia A patients divided into two groups (37 severe, 44 non-severe) were included in the study. The control group comprised 101 healthy male volunteers. Quantitative aPTT waveform analysis was performed with Actin FS on BCS (Siemens Healthcare Diagnostics, Marburg, Germany) using three parameters (DELTA, RATIO-1, RATIO-2) obtained from a single aPTT measurement with two evaluation modes. FVIII activities were measured by one-stage clotting and two-stage chromogenic assay. Statistically significant difference (P < 0.001) between control group and all haemophilia A patients, as well as between severe and non-severe haemophilia A patients was obtained for all quantitative waveform parameters. Our study revealed parameter DELTA as the best waveform parameter, showing significant correlation with FVIII activities and clinical parameters, and excellent performance for distinguishing between severe and non-severe haemophilia A patients (ROC analysis: sensitivity 97.3%, specificity 93.2%). The results obtained by new quantitative aPTT waveform analysis were superior to those obtained by standard laboratory methods. The simplicity and cost-benefit of the method make this approach a reasonable and promising tool for assessing coagulation in haemophilia A patients.

The burden of paediatric stroke and cerebrovascular disorders in Croatia.

Pediatric stroke is significantly less common than stroke in adults, but represents a major challenge to public health authorities. The aim of this retrospective study was to identify the total and annual number of children younger than 18 years with arterial ischaemic stroke and transient ischaemic attack referred to the Children's Hospital Zagreb, which is a major national centre specialised for the treatment and prevention of stroke in children. We reviewed the medical records of the Department of Neuropediatrics database at the Children's Hospital Zagreb between 1998-2005 in order to provide demographic and clinical characteristics and neuroimaging findings in children with arterial ischaemic stroke. In the 7-year period, we identified a total of 124 children from different geographic areas of Croatia with a confirmed diagnosis of transient ischaemic attack (N=77), and arterial ischaemic stroke (N=47). Perinatal and childhood arterial ischaemic stroke were equally represented (23 and 24 children, respectively). The average number of new cases identified each year was 18 cases (range: 12-21), seven arterial ischaemic stroke and 11 transient ischaemic attack cases. Male predominance was found in children with arterial ischaemic stroke with a male : female ratio of 1.76 : 1, and was slightly higher in childhood arterial ischaemic stroke compared with perinatal arterial ischaemic stroke (2 : 1 and 1.56 : 1, respectively). In contrast, transient ischaemic attack was more frequently found in girls, and more likely identified in older children compared with younger children with arterial ischaemic stroke. Obtained data will contribute to better understanding of paediatric stroke in Croatia and will provide a base for the establishment of the national referral center and national pediatric stroke registry.