Coagulation Factor Assay

Test Description

Whenever there is tissue injury or injury to blood vessels, platelets aggregate at the
area of the injury. These platelets release factors which begin the clotting process
(hemostasis). The original type of injury dictates the pathway by which the process
is initiated.

The intrinsic pathway is involved when there is damage to the blood or the blood
is exposed to collagen in the walls of traumatized blood vessels. The intrinsic pathway
requires the sequential activation of several coagulation factors: factor XII
(Hageman factor), factor XI (plasma thromboplastin antecedent), factor IX
(Christmas factor), and factor VIII (antihemophilic globulin).
The extrinsic pathway is launched when there is injury to tissue or to the vascular
wall. In this pathway, clotting is triggered by the release of tissue thromboplastin
(factor III) from the damaged vascular or tissue cells. When this substance
encounters factor VII (stable factor), the extrinsic pathway is stimulated.
Both pathways ultimately lead to the activation of coagulation factor X (Stuart-
Prower factor). This leads to the next step, in which prothrombin (factor II) is converted
to thrombin (factor IIa [activated]). Thrombin then stimulates the formation
of fibrin (factor Ia) from fibrinogen (factor I). This fibrin, with the addition of fibrin
stabilizing factor (XIII), forms a stable fibrin clot at the site of injury. Once the fibrin
clot is no longer needed, it is dissolved by fibrinolytic agents such as plasmin,
resulting in fibrin degradation products.

Any excess amounts of clotting factors which remain following hemostasis are
inactivated by fibrin inhibitors, such as antiplasmin, antithrombin III, and protein C.
This prevents clotting from occurring indiscriminately.
The coagulation factor assay is conducted to determine whether a congenital or
acquired deficiency of any blood clotting factor is present. This test is useful in
diagnosing hemophilia and/or coagulation disorders. In the test, the patient’s blood
is mixed with either normal serum or a prepared serum with a known specific deficiency.
The coagulation factor assay is performed after the review of other test
results which may indicate the factor which is possibly deficient.
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Normal Values

     50%–150% (Refer to reference laboratory for normal values for specific factor)
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Possible Meanings of Abnormal Values

Factor I (Fibrinogen)

Decreased

Congenital deficiency
Disseminated intravascular coagulation
Fibrinolysis
Liver disease
Factor II (Prothrombin)
Decreased
Congenital deficiency
Liver disease
Vitamin K deficiency

Factor V (Labile factor/Proaccelerin)

Decreased

Congenital deficiency
Deep venous thrombosis
Disseminated intravascular coagulation
Fibrinolysis
Liver disease
Pulmonary embolism

Factor VII (Stable factor/Proconvertin)

Decreased
Congenital deficiency
Hemorrhagic disease of the newborn
Kwashiorkor
Liver disease
Vitamin K deficiency

Factor VIII (Antihemophilic globulin)
Increased                                     Decreased

Coronary artery disease               Autoimmune disease
Cushing’s syndrome                    Congenital deficiency
Hyperthyroidism                         Disseminated intravascular coagulation
Hypoglycemia                             Fibrinolysis
Inflammation                               Hemophilia A
Late pregnancy                            von Willebrand’s disease
Macroglobulinemia
Myeloma
Postoperative period
Progesterone use
Rebound activity after sudden
      cessation of warfarin
Thromboembolic conditions

Factor IX (Christmas factor)
Decreased
Cirrhosis
Congenital deficiency
Disseminated intravascular coagulation
Hemophilia B (Christmas disease)
Hemorrhagic disease of newborn
Liver disease
Nephrotic syndrome
Normal newborn
Vitamin K deficiency

Factor X (Stuart-Prower factor)

Increased                                   Decreased

Pregnancy                                  Congenital deficiency
                                                   Disseminated intravascular coagulation
                                                   Liver disease
                                                  Vitamin K deficiency

Factor XI (Plasma thromboplastin antecedent)

Decreased

Congenital deficiency
Congenital heart disease
Hemophilia C
Intestinal malabsorption of vitamin K
Liver disease
Normal newborn
Stress
Vitamin K deficiency

Factor XII (Hageman factor)

Increased                                      Decreased

Exercise                                        Congenital deficiency
                                                      Nephrotic syndrome
                                                      Normal newborn
                                                       Pregnancy

Factor XIII (Fibrin stabilizing factor)

Decreased

Agammaglobulinemia
Hyperfibrinogenemia
Lead poisoning
Liver disease
Myeloma
Pernicious anemia
Postoperative period
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Contributing Factors to Abnormal Values

• Hemolysis of the blood sample may alter test results.
• Drugs which may alter values on the coagulation factor assay: anticoagulants.
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Interventions/Implications

Pretest

• Explain to the patient the purpose of the test and the need for a blood sample to be
   drawn.
• No fasting is required before the test.
• If possible, the patient should receive no warfarin sodium for 2 weeks or heparin for
2 days, prior to the test. Check with the primary care provider regarding the appropriateness
of withholding these medications from the patient.

Procedure

• A 7-mL blood sample is drawn in a light blue-top collection tube and immediately placed
on ice.
• Gloves are worn throughout the procedure.

Posttest

• Apply pressure 3 to 5 minutes at venipuncture site. Apply dressing, periodically assessing
for continued bleeding.
• Label the specimen and immediately transport it on ice to the laboratory.
• Teach the patient to monitor the site. If the site begins to bleed, the patient should apply
direct pressure and, if unable to control the bleeding, return to the laboratory or notify
the primary care provider.
• Resume any medications as taken prior to the test, if appropriate.
• Report abnormal findings to the primary care provider.
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Clinical alert         

• Possible complication: hematoma at site due to prolonged bleeding time.
• The prothrombin time and partial thromboplastin time can be analyzed to assist
         with determining what particular factor(s) may be deficient:
          • If the prothrombin time (PT) and activated partial thromboplastin time
          (APTT) are both abnormally prolonged, the deficiency is likely to involve
           factors II, V, or X.
           • If the PT is abnormal, but the APTT is normal, factor VII may be deficient.
           • If the PT is normal, but the APTT is abnormal, the deficient factor(s) may

              be from among those in the intrinsic pathway (VIII, IX, XI, XII).