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.

Hemophilia laboratory findings

In the United States, most people with hemophilia are diagnosed at a very young age. The median age at diagnosis is 36 months for people with mild hemophilia, 8 months for those with moderate hemophilia, and 1 month for those with severe hemophilia. In about two thirds of cases, there is a family history of hemophilia. The diagnosis of hemophilia is made using a special blood test and most babies can be tested soon after birth. Sometimes prenatal genetic testing is done to diagnose hemophilia before birth. For the one-third of babies born with hemophilia in families with no known history of hemophilia, the diagnosis is made when an unusual bleeding event occurs. Special blood tests are required to make the diagnosis.

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
Heamophilia A or B	Unaffected	Prolonged	Unaffected	Unaffected
Von Willebrand Disease	Unaffected	Prolonged or Unaffected	Prolonged	Unaffected
Thrombocytopenia	Unaffected	Unaffected	Prolonged	Decreased
Adapted from Wikipedia hemophilia Laboratory Finding> "Wikipedia Hemophilia Laboratory Finding".

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".

The test results will show whether you have hemophilia, what type of hemophilia you have, and how severe it is. Hemophilia A and B are classified as mild, moderate, or severe, depending on the amount of clotting factor VIII or IX in the blood. The severity of symptoms can overlap between the categories. For example, some people who have mild hemophilia may have bleeding problems almost as often or as severe as some people who have moderate hemophilia. Severe hemophilia can cause serious bleeding problems in babies. Thus, children who have severe hemophilia usually are diagnosed during the first year of life. People who have milder forms of hemophilia may not be diagnosed until they're adults.

Severity	Levels of Factor VIII (8) or IX (9) in the blood
Normal (person who does not have hemophilia)	50% to 100%
Mild hemophilia	Greater than 5% but less than 50%
Moderate hemophilia	1% to 5%
Severe hemophilia	Less than 1%
Adapted from CDC Hemophilia Diagnosis> "CDC Hemophilia Diagnosis".