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Haemostasis
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Thrombin time measures how quickly a clot forms when a standard amount of bovine thrombin is added to a platelet with poor preparation of the patient's plasma. It tests the interaction between thrombin and fibrinogen. It is prolonged in fibrinogen deficiency.
Acquired Circulating Anticoagulants Other than Lupus Anticoagulants
Published in E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson, Phospholipid-Binding Antibodies, 2020
Antibodies reacting with factor X appear to be rather rare, through variable deficiencies of factor X occur in patients with amyloid.129 The deficiency is due to the binding of factor X to the amyloid fibrils. Thus, infused factor X has a shortened half-life in vivo in such patients because of its accelerated removal. In one case, removal of the spleen heavily infiltrated with amyloid resulted in normalization of factor X levels.3 Many of these patients may also demonstrate a prolonged thrombin time.130
Congenital Platelet Dysfunction and von Willebrand Disease
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
In the screening tests of secondary hemostasis, only the partial thromboplastin time was abnormal. This information is extremely helpful. The observed pattern of results provides no suggestion for a deficiency of coagulation factors participating in the extrinsic pathway or in the common pathway. The normal thrombin time confirms that the patient’s fibrinogen is likely to function normally in coagulation. Certainly the combination of a prolonged bleeding time and a prolonged FIT should immediately raise the question of vWD because, since vWF serves both as a participant with platelets in primary hemostasis and as a carrier for the factor VIII that is critical to secondary hemostasis, a deficiency of vWF would appear capable of explaining all the available findings.
Rare inherited coagulation disorders in young children in Oman
Published in Pediatric Hematology and Oncology, 2022
Surekha Tony, Roshan Mevada, Abdulhakim Al Rawas, Yasser Wali, Mohamed Elshinawy
Laboratory diagnosis usually starts with the assessment of the coagulation screening tests activated partial thromboplastin time (APTT) and prothrombin (PT). A prolonged APTT with normal PT suggests FXI deficiency after exclusion of FVIII, FIX, and FXII defects. The reverse pattern is usually due to a FVII deficiency, while the prolongation of APTT and PT together suggests the diagnosis of combined FV + FVIII, FX, FV, FII or fibrinogen deficiencies. To evaluate fibrinogen deficiency thrombin time (TT) is also important. When screening coagulation tests are abnormal, mixing analysis (50:50) must be done to exclude the presence of an inhibitor. Therefore, specific factor assays are performed to identify the deficiency. The diagnosis of FXIII defect requires specific tests, because all screening clotting assays are normal. Molecular diagnosis allows to identify the pathogenic mutation in genes that encode corresponding clotting factors.19,20
Characterization of the hemorrhagic syndrome in the New Zealand white rabbit model following total body irradiation
Published in International Journal of Radiation Biology, 2021
Isabel L. Jackson, Ganga Gurung, Emmanuel Ayompe, Elena-Rose Fown, Sarah Triesler, Buddha Mali, Andrea Casildo, Allison Gibbs, Yannick Poirier, Eric P. Cohen, Diana Newman, Zeljko Vujaskovic
Prothrombin time (PT) appeared to be shortened in response to radiation (Figure 4). Shortened activated partial thromboplastin times (aPTT) were observed during the first- to second-week post-exposure, but this did not achieve statistical significance (one-way ANOVA with Tukey’s multiple comparisons test). The shortened prothrombin time was observed at a higher rate among animals in the 7.0 Gy arm (11/19; 57.9%) than the 7.5 Gy arm (n = 9/31; 29%). A shortened thrombin time was observed during the second week post-exposure (e.g. 11−13.8 seconds and 13.4−13.5 seconds, unscheduled vs. scheduled) vs. 14.1−17.8 seconds. However, there was a marked difference in thrombin time between animals euthanized due to study endpoint (scheduled) vs. criteria (unscheduled) in the 7.5 Gy arm. Antithrombin was elevated in animals between days 5 and 20 regardless of TBI dose, with the most noticeable elevation occurring during the second-week post-exposure after which values returned to normal. One animal presented with antithrombin deficiency (37.2% of normal activity) on day 7 post-exposure to 7.0 Gy (Figure 4).
Perioperative management of anticoagulation
Published in Hospital Practice, 2020
Goutham Talari, Zachary D. Demertzis, Robert D. Summey, Baljinder Gill, Scott Kaatz
Thrombin time can be prolonged when dabigatran levels are below the therapeutic range, but they are always prolonged or out of range when the drug levels are within or above normal range [24,27]. The thrombin time is oversensitive to dabigatran and is prolonged in the presence of the dabigatran. A normal thrombin time excludes the presence of dabigatran, and hence possibly can be used as screening test [27]. Other nonspecific and less sensitive assays like thrombin generation assays, dilute prothrombin time, activated clotting time, prothrombinase induced clotting time, rotational thromboelastometry, endogenous thrombin potential, and thromboelastography are mentioned in the literature but are rarely of practical value at this time, and normal levels do not necessarily exclude important dabigatran levels [24,27].