thrombin

[throm´bin]

1. the activated form of coagulation factor II (prothrombin), which catalyzes the conversion of fibrinogen to fibrin.

2. a preparation of this compound prepared from prothrombin of bovine origin, used as a topical hemostatic.

thrombin time (TT) the time required for plasma fibrinogen to form thrombin: exogenous thrombin is added to citrated plasma and the time to clot formation is measured. Prolonged TT is seen with abnormalities of fibrinogen and in the presence of heparin or degradation products of fibrin or fibrinogen.

time

[tīm]

a measure of duration. See under adjectives for specific times, such as bleeding time.

activated partial thromboplastin time (APTT, aPTT) the period required for clot formation in recalcified blood plasma after contact activation and the addition of platelet substitutes such as brain cephalins or similar phospholipids; used to assess the coagulation pathways. A prolonged aPTT can indicate a deficiency of any of various coagulation factors, including factors XII, XI, IX, VIII, X, V, and II, and fibrinogen.

AEC minimal response time the shortest duration at which x-ray exposure can be terminated by automatic exposure control.

atrioventricular sequential time a fixed nonprogrammable interval that extends from the atrial stimulus to the ventricular stimulus.

bleeding time the time required for a standardized wound to stop bleeding; used as a test for platelet disorders; see also bleeding time.

circulation time the time required for blood to flow between two given points; see also circulation time.

clotting time (coagulation time) the time required for blood to clot in a glass tube; see also clotting.

cold ischemia time the time between the placement of a traumatically amputated body part in ice and the time of surgical replantation.

inertia time the time required to overcome the inertia of a muscle after reception of a stimulus.

ischemia time the total time between traumatic amputation of a limb or portion of a limb and its surgical reimplantation; it is the sum of warm and cold ischemia times.

minimal response time in radiology, the shortest possible exposure time for an x-ray film to be exposed automatically.

one-stage prothrombin time prothrombin time.

prothrombin time see prothrombin time.

real time a term used to describe a recording device that shows events simultaneously to their occurrence.

R peak time intrinsicoid deflection.

thrombin time the time required for plasma fibrinogen to form thrombin; see also thrombin time.

warm ischemia time the time interval between traumatic amputation of a limb or part and its placement on ice.

throm·bin time

the time needed for a fibrin clot to form after the addition of thrombin to citrated plasma; prolonged thrombin time is seen in patients receiving heparin therapy.

Farlex Partner Medical Dictionary © Farlex 2012

thrombin time

Thrombin clotting time Lab medicine A test used to evaluate the final stage of coagulation–the conversion of fibrinogen to fibrin; it is ↑ in deficiency or defects of fibrinogen, or in the presence of FDPs or heparin-coagulation products; it is used clinically to determine adequacy of thrombolytic therapy. See Reperfusion therapy, Streptokinase, tPA, Urokinase.

throm·bin time

(TT) (thrombin tīm)

Duration needed for a fibrin clot to form after the addition of thrombin to citrated plasma; thrombase.

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

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References in periodicals archive

Evaluation based on personal or family history of bleeding, particularly mucocutaneous type, or female with menorrhagia though not a specific marker of VWD.4 Studies have reported a prevalence of VWD of between 5% and 20% among women who have menorrhagia.32,33 An initial haemostasis laboratory work up includes a bleeding time, platelet count and complete blood count (CBC), activated partial thromboplastin time (APTT), prothrombin time (PT), and optionally either a fibrinogen level or a thrombin time (TT).This testing neither "rules in" nor "rules out" VWD, but can suggest whether coagulation factor deficiency or thrombocytopenia might be the cause of clinical bleeding.

Guidelines on the laboratory diagnosis of congenital bleeding disorders in Pakistan

* Student should seek prothrombin and partial thrombin time results before starting heparin.

Patient care simulations: role playing to enhance clinical understanding

Qualitative PT (a) PT (a) assessment of NO AC levels Quantitative Chromogenic anti-factor Chromogenic assessment of NO AC Xac anti-factor Xa (c) levels Abbreviations: aPTT, activated partial thromboplastin time; dTT, dilute thrombin time; ECA, ecarin chromogenic assay; ECT, ecarin clotting time; FDA, US Food and Drug Administration; INR, international normalized ratio; N/A, not applicable; NOAC, novel oral anticoagulant; PT, prothrombin time; TT, thrombin time.

Novel Oral Anticoagulants: Efficacy, Laboratory Measurement, and Approaches to Emergent Reversal

In hypercoagulation group of response in spring we observed the shortage of activated recalcification time of the common and thrombocytes-free plasma and the tendency to the shortage of thrombin time. In hypocoagulation group the work induced a certain increase of activated recalcification time of thrombocytes-free plasma, thrombin time and a significant increase of free heparin.

Seasonal features of the clotting reactions to physical load

Effect of a 2-week oral treatment with EPs[R] 7630 on the thromboplastin time (TPT), the partial thromboplastin time (PTPT) and the thrombin time (TT) in rats.

Treatment of rats with the Pelargonium sidoides extract EPs[R] 7630 has no effect on blood coagulation parameters or on the pharmacokinetics of warfarin

A 49-year-old African-American female with history of hepatitis C and hypertension was investigated for a possible dysfibrinogenemia when an abnormal thrombin time (TT) and reptilase time (RT) were reported by the laboratory.

Unexpected laboratory diagnosis: acquired dysfibrinogenemia in a bleeding patient with liver disease

Several common coagulation assays including thrombin time (TT), dilute TT (dTT), prothrombin time (PT), dilute PT (dPT), and activated partial thrombin time (aPTT) have also been evaluated to determine if clotting times would correlate with dabigatran concentrations (5).

To monitor dabigatran or not: a matter of patient safety

The thrombin time is the time needed for thrombin to convert fibrinogen to an insoluble fibrin clot.

Specialized tests for hemostasis

* Rely on a "normal" thrombin time to rule out clinically relevant concentrations of dabigatran, because this test is sensitive to very low concentrations (approximately 25 [micro]g/L) (4).

Warfarin replacements: good for patients, challenging for laboratories

(4) Asymptomatic dysfibrinogenemia is usually brought to clinical attention because of an abnormal laboratory test (ie, thrombin time).

Laboratory diagnosis of dysfibrinogenemia

The prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) will all be prolonged because of the consumption of the coagulation factors - although with the advent of D-dimer, TT is no longer offered as a routine test.

A review of disseminated intravascular coagulation: presentation, laboratory diagnosis and treatment