Here’s a rundown of the various blood tests providers use to diagnose hemophilia, vonWillebrand Disease and other bleeding disorders.
by: Michael Hickey
Doctors use a number of tests to pinpoint the cause of a person’s excessive or abnormal bleeding. Read on for an overview of the most common blood tests used to diagnose hemophilia and other bleeding disorders, as well as when and where to get tested.
How to Test for Hemophilia
There are a number of tests available, each with its own purpose. Screening tests are blood tests that show if the blood is clotting properly. The procedure involves providing your doctor with a blood sample. Types of screening tests include:
- Complete blood count (CBC) test: This test measures, counts, evaluates and studies certain aspects of your blood, including the amount of hemoglobin, the size and number of red blood cells, and the number of different types of white blood cells and platelets found in the blood. If a person with hemophilia has heavy bleeding or bleeds for a long time, the hemoglobin and red blood cell counts can be low.
- Activated partial thromboplastin time (APTT) test: This test evaluates how long it takes a person’s blood to form a clot. It measures the clotting ability of factors VIII, IX, XI and XII, and results are compared against a normal reference interval for clotting time.
- Prothrombin time (PT) test: This test also measures the time it takes for blood to clot, but it assesses factors I, II, V, VII and X. If any of these factors are too low, clotting takes longer than normal.
- Fibrinogen test: This test shows how well you form clots by measuring the amount and evaluating the function of fibrinogen—also known as coagulation factor I—in your blood.
Meanwhile, another type of test, clotting factor tests (also called factor assays), measures the amount of factor proteins in your blood. These are used to determine the type and severity of a bleeding disorder; hemophilia is caused when coagulation factors VIII or IX are missing or defective.
When to Test for Hemophilia
You should get tested if family members have been diagnosed with bleeding disorders or if you’re aware of a family history of excessive or abnormal bleeding (after surgery or an injury, for example), as most bleeding disorders are inherited. And if there have been unexplained deaths among siblings or male relatives such as maternal uncles, grandfathers or cousins, you should discuss them with a doctor to see if hemophilia was a cause and if you should get tested yourself.
That said, about one-third of people who are diagnosed with hemophilia have no other family members with the disorder. Doctors may test people with no family history of bleeding disorders if they show symptoms such as prolonged bleeding after blood draws or heel sticks (pricking an infant’s heel to draw blood for newborn screening tests), bleeding in the scalp or brain after a difficult delivery, spontaneous bleeding in joints or muscles, or unusual or frequent bruising.
Where to Test for Hemophilia
University of California San Francisco Health says, “Testing for hemophilia should be performed at a highly experienced specialized coagulation laboratory. Laboratories that do not frequently perform these specialized tests may not be able to accurately establish a diagnosis.”
When Is Hemophilia Diagnosed?
Severe cases of hemophilia are often diagnosed at an early age, usually in the first year of a baby’s life, as symptoms become apparent in children as soon as they start moving or crawling. However, milder bleeding disorders may not be diagnosed until the person is an adult and experiences a bleeding episode stemming from trauma or surgery.
A prenatal diagnosis is also possible, as genetic mutations can cause hemophilia. Prenatal tests for hemophilia are performed after doctors identify a specific genetic mutation in a parent or close relative with the condition.
Stay tuned for the Spring/Summer 2022 issue of HemAware, which will feature an article about the struggles that Black women often face regarding the diagnosis and treatment of their bleeding disorder.
Source: National Hemophilia Foundation