coagulating factors concentration (Coagulating factors, Blood-clotting factors)
المؤلف:
Kathleen Deska Pagana, Timothy J. Pagana, Theresa Noel Pagana.
المصدر:
Mosbys diagnostic and laboratory test reference
الجزء والصفحة:
15th edition , p250-254
2025-11-12
71
Type of test Blood
Normal findings
Test explanation and related physiology
These tests measure the quantity of each specific factor thought to be responsible for suspected defects in hemostasis. Testing is available to measure the quantity of the factors listed in the normal findings section. When these factors exist in concentrations below their minimal hemostatic levels, clotting is impaired. Deficiencies of these factors may be a result of inherited genetic defects, acquired diseases, or drug therapy. Common medical conditions associated with abnormal factor concentrations are listed in Table 1.
Table1. Conditions that may result in coagulation factor excess or deficiency
Table1. Conditions that may result in coagulation factor excess or deficiency—cont'd
The hemostasis and coagulation system is a homeostatic balance between factors encouraging clotting and those encouraging clot dis solution (Figure1). See Table 2 for a list of factor names and routine coagulation test abnormalities associated with factor deficiency.
Fig1. Secondary hemostasis (fibrin clot formation) and fibrinolysis (fibrin clot dissolution). Primary hemostasis involves platelet plugging of the injured blood vessel. Secondary hemostasis, as described here, takes place most rapidly on the platelet surface after attachment to the fractured endothelium. Four different reactions result in the formation of fibrin. As seen beneath the dark line in the figure, the fibrin clot supports the platelet clump so that the clot does not get swept away by the tremendous shear forces of the fast moving blood cells. Fibrinolysis follows formation of the fibrin clot in order to prevent complete occlusion of the injured blood vessel.
Table2. List of minimum concentration of coagulation factors required for fibrin production a
Fibrinogen (or factor I; p. 426), like many of the coagulation proteins, is considered an acute reactant protein and is elevated in many severe illnesses. It is also considered a risk factor for coronary heart disease and stroke.
Prothrombin is a vitamin K–dependent clotting factor. Its production in the liver requires vitamin K. This vitamin is fat soluble and is dependent on bile for absorption.
Factor VIII is actually a complex molecule with two com ponents. The first component is related to hemophilia A and is involved in the hemostatic mechanism. The second component is von Willebrand factor and is related to von Willebrand disease. Von Willebrand Disease gene (VWF Gene) detects pathogenic alterations within the VWF gene to delineate the under lying molecular defect in a patient with a laboratory diagnosis of von Willebrand disease (VWD). This second component is involved in platelet adhesion and aggregation.
Coagulation factor inhibitors arise in patients who are congenitally deficient in a specific factor in response to factor replacement therapy. They can also occur spontaneously without known cause or in response to a variety of medical conditions, including the postpartum state, immunologic disorders, certain antibiotic therapies, some malignancies, and old age.
In most cases, a factor deficiency can be diagnosed by identifying the mutated gene using next-generation sequencing (NGS). NGS is also helpful in identifying carrier status for close family members of an individual with a factor VII deficiency diagnosis.
Interfering factors
• Many of these proteins are heat sensitive, and levels are decreased if the specimen is kept at room temperature.
• Pregnancy or the use of contraceptive medication can increase levels of several of these factors, especially VIII and IX.
• Many of these protein coagulation factors are acute reactant proteins. Acute illness, stress, exercise, or inflammation can raise levels.
Procedure and patient care
• See inside front cover for Routine Blood Testing.
• Fasting: no
• Blood tube commonly used: blue
Abnormal findings
See Table 1.
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