Hemophilia laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
Laboratory findings consistent with the diagnosis of hemophilia include unaffected prothrombin time, prolonged partial thromboplastin time, unaffected bleeding time and unaffected platelet count.
Screening Tests
Screening tests are blood tests that show if the blood is clotting properly. Types of screening tests:
Complete Blood Count (CBC)
This common test measures the amount of hemoglobin (the red pigment inside red blood cells that carries oxygen), the size and number of red blood cells and numbers of different types of white blood cells and platelets found in blood. The CBC is normal in people with hemophilia. However, if a person with hemophilia has unusually heavy bleeding or bleeds for a long time, the hemoglobin and the red blood cell count can be low.
Activated Partial Thromboplastin Time (APTT) Test
This test measures how long it takes for blood to clot. It measures the clotting ability of factors VIII (8), IX (9), XI (11), and XII (12). If any of these clotting factors are too low, it takes longer than normal for the blood to clot. The results of this test will show a longer clotting time among people with hemophilia A or B.
Prothrombin Time (PT) Test
This test also measures the time it takes for blood to clot. It measures primarily the clotting ability of factors I (1), II (2), V (5), VII (7), and X (10). If any of these factors are too low, it takes longer than normal for the blood to clot. The results of this test will be normal among most people with hemophilia A and B.
Fibrinogen Test
This test also helps doctors assess a patient’s ability to form a blood clot. This test is ordered either along with other blood clotting tests or when a patient has an abnormal PT or APTT test result, or both. Fibrinogen is another name for clotting factor I (1).
Clotting Factor Tests
Clotting factor tests, also called factor assays, are required to diagnose a bleeding disorder. This blood test shows the type of hemophilia and the severity. It is important to know the type and severity in order to create the best treatment plan.
| Condition | Prothrombin time | Partial Thromboplastin Time | Bleeding Time | Platelet Count |
|---|---|---|---|---|
| Hemophilia A or B | Unaffected | Prolonged | Unaffected | Unaffected |
| Von Willebrand Disease | Unaffected | Prolonged or Unaffected | Prolonged | Unaffected |
| Thrombocytopenia | Unaffected | Unaffected | Prolonged | Decreased |
| Vitamin K deficiency or Warfarin | Prolonged | Normal or mildly prolonged | Unaffected | Unaffected |
| Disseminated Intravascular Coagulation | Prolonged | Prolonged | Prolonged | Decreased |
| Liver failure, early | Prolonged | Unaffected | Unaffected | Unaffected |
| Aspirin | Unaffected | Unaffected | Prolonged | Unaffected |
| Liver failure, end-stage | Prolonged | Pronlonged | Prolonged | Decreased |
| Uremia | Unaffected | Unaffected | Prolonged | Unaffected |
| Congenital afibrinogenemia | Prolonged | Prolonged | Prolonged | Unaffected |
| Factor V deficiency | Prolonged | Prolonged | Unaffected | Unaffected |
| Factor X deficiency as seen in amyloid purpura | Prolonged | Prolonged | Unaffected | Unaffected |
| Glanzmann's thrombasthenia | Unaffected | Unaffected | Prolonged | Unaffected |
| Bernard-Soulier syndrome | Unaffected | Unaffected | Prolonged | Decreased |
| Factor XII deficiency | Unaffected | Unaffected | Prolonged | Decreased or unaffected |
| C1INH deficiency | Unaffected | Shortened | Unaffected | Unaffected |
| Adapted from Wikipedia hemophilia Laboratory Finding> "Wikipedia Hemophilia Laboratory Finding". | ||||