Fibrin degradation product (FDP) and d-dimer levels | FDP: variable depending on specific test, typically <2.5 to 10 micrograms/mL d-Dimer: variable depending on specific test, typically <250 to 500 ng/mL | FDP test: measures breakdown products from fibrinogen and fibrin monomer d-Dimer test: measures breakdown products of cross-linked fibrin | Levels are elevated in diffuse intravascular coagulation, venous thrombosis, pulmonary embolus, and liver disease, and during pregnancy |
Factor level assays | 60% to 130% of reference value (0.60 to 1.30 units/mL) | Measures the percent activity of a specified factor compared to normal | To identify specific deficiencies and direct therapeutic management |
Protein C level | Variable | Level of protein C in the blood | Vitamin K dependent |
| Typically 60% to 150% of reference value | | Increases with age |
| | | Values higher in males than females |
| | | Deficiency associated with thromboembolism in people <50 y of age |
Protein S level | Variable Typically 60% to 150% of reference value | Level of protein S in the blood | Vitamin K dependent Increases with age Values higher in males than females Deficiency associated with thromboembolism in people <50 y of age |
Factor V Leiden (FVL) | Variable | Screening test looks for activated protein C resistance and confirmatory test analyzes DNA sequence of Factor V gene | FVL not inactivated by activated protein C |
| | Screening assay uses activated partial thromboplastin time with and without added activated protein C | Heterozygotes have 7x and homozygotes have a 20x increased lifetime risk of venous thrombosis Mutation associated with thromboembolism in people <50 y of age |
Antithrombin level | Variable depending on specific test Typically 20 to 45 milligrams/dL | Measures level of antithrombin in the blood | Not vitamin K dependent; patients with deficiency require higher dosages of heparin for anticoagulation therapy Deficiency associated with thromboembolism in people <50 y of age |
Antiphospholipid antibodies | IgG <23 GPL units/mL and IgM <11 MPL units/mL | Tests for antibodies that bind to phospholipids | Lupus anticoagulant: elevated in systemic lupus erythematosus (SLE) and other autoimmune diseases |
| | Lupus anticoagulant | Anticardiolipin antibody: elevated in SLE, other autoimmune diseases, syphilis, and Behçet syndrome |
| | Anticardiolipin antibody | Increased risk of spontaneous abortions, fetal loss, and fetal growth retardation |
Anti–Factor Xa activity | Therapeutic: 0.7 to 1.1 units/mL | Inhibition of Factor Xa activity | Used to monitor low-molecular-weight heparin therapy |
| Prophylactic: 0.2 to 0.3 units/mL | | May be elevated in renal dysfunction |
Platelet function assay | 88 to 198 s Variable | Tests for platelet adhesion and aggregation | Affected by uremia, anemia, thrombocytopenia, antiplatelet medications, and von Willebrand disease |
Peripheral blood smear | Qualitative and quantitative based on visualization | Estimates quantity and appearance of platelets, white blood cells, and red blood cells | Allows identification of clumped platelets, abnormal cells interfering with coagulation (leukemia), operator dependent |
Dilute Russell viper venom time | 23 to 27 s | Venom directly activates Factor X and converts prothrombin to thrombin when phospholipid and Factor V are present | Prolonged in the presence of antiphospholipid antibodies |
Inhibitor screens | Variable | Verifies the presence or absence of antibodies directed against one or more of the coagulation factors | Specific inhibitors: directed against one coagulation factor, most commonly against Factor VIII Nonspecific inhibitors: directed against more than one coagulation factor; example is lupus-type anticoagulant |
PIVKA II (proteins induced by vitamin K absence or antagonism) test | Variable | Measures nonfunctional precursors of vitamin K–dependant coagulation factors (II, VII, IX, X) | Increased in vitamin K–deficient states, such as hemorrhagic disease of the newborn, and can differentiate it from nonaccidental trauma Increased in overdoses of warfarin or cholestatic liver diseases that can respond to vitamin K therapy |