Several blood tests that measure the activity of different clotting factors in your blood are necessary to diagnose hemophilia.
An uncommon bleeding illness called hemophilia makes it impossible for your blood to clot properly. It occurs due to your blood’s clotting factors—special proteins—not being present.
Hemophilia primarily affects those assigned male at birth and is a very uncommon condition that usually runs in families. It is estimated by the Centers for Disease Control and Prevention (CDC) that approximately 33,000 males in the US suffer from hemophilia.
Numerous lab tests assist a doctor to confirm the diagnosis of hemophilia if they have suspicions about your condition. Most diagnostic procedures for this illness include drawing blood.
The needle used during this treatment usually causes only mild discomfort. Rarely, swelling and inflammation of your vein at the puncture site may occur. But keep in mind that hemophilia can also result in prolonged bleeding following a blood transfusion.
You will learn about the several tests used by medical professionals to detect hemophilia in this post.
Clotting factor tests
Physicians mostly employ clotting factor tests, sometimes referred to as factor assays, to diagnose hemophilia. They check for the presence of several proteins called clotting factors, which aid in blood clotting.
Hemophilia A is a kind of hemophilia that is commonly caused by a deficiency in clotting factor VIII. Hemophilia B, on the other hand, results from a lack of clotting factor IX. Hemophilia of other kinds is less common.
The amounts of clotting factors VIII and IX in your blood are determined by clotting factor testing. The degree of hemophilia can also be ascertained by these tests.
| Hemophilia A or B severity | Levels of clotting factors VIII or IX in the blood |
|---|---|
| mild | 6% to 40% |
| moderate | 1% to 5% |
| severe | less than 1% |
Complete blood count
A routine test called a complete blood count (CBC) counts several elements of your blood, such as:
- hemoglobin
- red blood cells
- white blood cells
- platelets
A comprehensive picture of your overall blood health is provided by the CBC. Anemia, which affects those who experience bleeding episodes frequently, can be detected by it. Additionally, it can identify blood diseases and infections that could exacerbate hemophilia.
Activated partial thromboplastin time (APTT) test
The test known as activated partial thromboplastin time, or APTT, measures the amount of time your blood takes to clot. It is frequently used by doctors to identify bleeding diseases, such as hemophilia.
Your blood will be mixed with clotting-promoting substances by a doctor to conduct this test. The time it takes for your blood to coagulate is then measured by the lab.
On an APTT test, the normal range for clotting times is 25–35 seconds. Hemophilia or similar clotting conditions may be indicated by longer-than-normal clotting times.
Prothrombin time (PT) test
Another test that determines how long it takes for your blood to clot is the prothrombin time (PT) test.
Although the method is similar to that of the APTT test, the chemicals used to measure clotting times are different. Additionally, it monitors the activity of many clotting factors. PT test results for individuals with hemophilia A or B often range from 10 to 13 seconds because it does not test for factors VIII and IX.
The international normalized ratio (INR), which expresses your PT result in comparison to a standard control, is another metric that medical professionals may employ. When both your test and the control test have the same time, the INR is 1.0. The range of an INR is 0.8 to 1.2.
PT and APTT testing in hemophilia
Because the APTT and PT tests evaluate the activity of various clotting factors, doctors typically prescribe them together.
| PT test measures | APTT test measures |
|---|---|
| • factor I • factor II • factor V • factor VII • factor X |
• factor VIII • factor IX • factor XI • factor XII |
Fibrinogen test
Another name for clotting factor I is fibrinogen. As with other factor assays, the level of factor I in your blood is determined by this test.
200 to 400 milligrams per deciliter (or 2 to 4 grams per liter) is the range of healthy plasma fibrinogen levels. Low levels are indicative of fibrinogen insufficiency, a clotting condition.
Genetic testing
By detecting abnormalities in the genes that produce clotting factors VIII or IX, genetic testing can validate a hemophilia A or B diagnosis.
A blood sample is usually required for genetic testing, much like for other hemophilia tests. After that, a physician will submit a sample to a lab for DNA analysis.
Additionally, genetic testing can identify if you are a carrier of a hemophilia mutation, which means that even though you don’t have hemophilia, you can still pass it on to your offspring. This could be crucial in terms of family planning.
People with a history of hemophilia in their family are usually subject to genetic testing. A relative assigned male at birth with hemophilia should also have a genetic test to identify the precise mutation causing hemophilia in your family for the most accurate results.
Takeaway
Hemophilia is diagnosed using a battery of blood tests that gauge the concentration of clotting components in your blood, assess blood clotting times, and identify the genetic abnormalities causing this disorder. Every test yields important data to assist medical practitioners in accurately diagnosing patients.
Blood testing might be unsettling at times. However, feeling more prepared and in control can be achieved by being aware of the processes, what they measure, and how to interpret the results. To make sure you get the best care possible, always talk to your doctor about your worries and the results.