Davis's Lab & Diagnostic Tests
Coagulation Factors
General
Synonym/Acronym:
See table on the next page.
Rationale
To detect factor deficiencies and related coagulopathies such as found in disseminated intravascular coagulation (DIC).
Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.
Normal Findings
(Method: Photo-optical clot detection) Activity from 50% to 150%.
| Preferred Name | Synonym | Role in Modern Coagulation Cascade Model | Coagulation Test Responses in the Presence of Factor Deficiency | |
|---|---|---|---|---|
| Factor I | Fibrinogen | — | Assists in the formation of the fibrin clot | PT prolonged, aPTT prolonged |
| Factor II | Prothrombin | Prethrombin | Assists factor Xa in formation of trace thrombin in the initiation phase and assists factors VIIIa, IXa, Xa, and Va to form thrombin in the propagation phase of hemostasis | PT prolonged, aPTT prolonged |
| Tissue factor (TF) (formerly known as factor III) | TF | Tissue thromboplastin | Assists factor VII and Ca2+ in the activation of factors IX and X during the initiation phase of hemostasis | PT prolonged, aPTT prolonged |
| Calcium (formerly known as factor IV) | Calcium | Ca2+ | Essential to the activation of multiple clotting factors | N/A |
| Factor V | Proaccelerin | Labile factor, accelerator globulin (AcG) | Assists factors VIIIa, IXa, Xa, and II in the formation of thrombin during the amplification and propagation phases of hemostasis | PT prolonged, aPTT prolonged |
| Factor VII | Proconvertin | Stabile factor, serum prothrombin conversion accelerator, autoprothrombin I | Assists TF and Ca2+ in the activation of factors IX and X | PT prolonged, aPTT normal |
| Factor VIII | Antihemophilic factor (AHF) | Antihemophilic globulin (AHG), antihemophilic factor A, platelet cofactor 1 | Activated by trace thrombin during the initiation phase of hemostasis to amplify formation of additional thrombin | PT normal, aPTT prolonged |
| Factor IX | Plasma thromboplastin component (PTC) | Christmas factor, antihemophilic factor B, platelet cofactor 2 | Assists factors Va and VIIIa in the amplification phase and factors VIIIa, Xa, Va, and II to form thrombin in the propagation phase | PT normal, aPTT prolonged |
| Factor X | Stuart-Prower factor | Autoprothrombin III, thrombokinase | Assists with formation of trace thrombin in the initiation phase and acts with factors VIIIa, IXa, Va, and II to form thrombin in the propagation phase | PT prolonged, aPTT prolonged |
| Factor XI | Plasma thromboplastin antecedent (PTA) | Antihemophilic factor C | Activated by thrombin produced in the extrinsic pathway to enhance production of additional thrombin inside the fibrin clot via the intrinsic pathway; this factor also participates in slowing down the process of fibrinolysis | PT normal, aPTT prolonged |
| Factor XII | Hageman factor | Glass factor, contact factor | Contact activator of the kinin system (e.g., prekallikrein, and high-molecular-weight kininogen) | PT normal, aPTT prolonged |
| Factor XIII | Fibrin-stabilizing factor (FSF) | Laki-Lorand factor (LLF), fibrinase, plasma transglutaminase | Activated by thrombin and assists in formation of bonds between fibrin strands to complete secondary hemostasis | PT normal, aPTT normal |
| von Willebrand factor | von Willebrand factor | vWF | Assists in platelet adhesion and thrombus formation | Ristocetin cofactor decreased |
Critical Findings and Potential Interventions
- Fibrinogen: Less than 80 mg/dL (SI: Less than 2.4 micromol/L)
Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.
Signs and symptoms of microvascular thrombosis include cyanosis, ischemic tissue necrosis, hemorrhagic necrosis, tachypnea, dyspnea, pulmonary emboli, venous distention, abdominal pain, and oliguria. Possible interventions include identification and treatment of the underlying cause, support through administration of required blood products (cryoprecipitate or fresh frozen plasma), and administration of heparin. Cryoprecipitate may be a more effective product than fresh frozen plasma in cases where the fibrinogen level is less than 100 mg/dL (SI: 2.94 micromol/L), the minimum level required for adequate hemostasis, because it delivers a concentrated amount of fibrinogen without as much plasma volume. Further information regarding fibrinogen can be found in the study titled “Fibrinogen.”
There's more to see -- the rest of this topic is available only to subscribers.
