Definition

Hemophilia A is a common blood clotting disorder characterized by an impaired clotting process, which increases the risk of uncontrolled bleeding.

Factor VIII, a protein crucial for blood clotting, plays a vital role in preventing excessive bleeding. Under normal circumstances, proteins like factor VIII work together to form clots and stop bleeding promptly. A deficiency in factor VIII may lead to hemophilia A.

Indications

A factor VIII test is recommended if there is a family history of hemophilia or other blood disorders. Physicians may also order this test if you exhibit one or more of the following symptoms:

• Unexplained prolonged bleeding after minor cuts, surgeries, or dental procedures
• Easy bruising
• Slow wound healing due to repeated bleeding or infections
• Joint pain and stiffness
• Heavy menstrual bleeding
• Severe, one-sided lower back pain
• A need for blood transfusions following minor injuries

Additionally, this test may be performed if other blood clotting tests reveal abnormalities.

Contraindications

Factor VIII testing is generally safe, with moderate risks. There are no specific contraindications associated with this test. If you have undergone blood sampling before, this procedure is similar.

Preparation before the Test

No specific preparation is required for a factor VIII test. However, fasting may be necessary if the test is part of a series of tests. Some medications, including blood thinners such as warfarin and enoxaparin, as well as NSAIDs like aspirin, ibuprofen, or naproxen, can influence the test results.

Inform your doctor about your medical history and medication usage beforehand. Your doctor may recommend discontinuing certain medications before the test, depending on the blood clotting factors being evaluated.

Test Procedure

The factor VIII test involves collecting a blood sample. A laboratory technician will cleanse the skin on your arm with an alcohol swab before drawing a small amount of blood from a vein using a sterile syringe. In infants, blood is typically collected from the heel.

When drawing blood from a vein, the technician will first clean the skin with an antiseptic and tie a tourniquet around the arm to apply pressure, causing the blood vessel to fill with blood. The needle will be inserted into a vein—commonly in the inner elbow or back of the hand—and blood will be collected into a vial or syringe. Afterward, the tourniquet is removed, and the area is covered with a bandage to stop the bleeding.

The collected blood is placed in a specialized tube and analyzed using laboratory equipment. Results are usually available within a day. The risks associated with the test are minimal, though some individuals may experience temporary pain, dizziness, or bruising at the blood draw site. The entire procedure typically takes about 10 minutes.

Normal and Abnormal Values

Factor VIII test results are typically presented as a percentage. Normal factor VIII activity levels range between 50% and 150%, with 100% being the standard reference value. Abnormal values are characterized by factor VIII activity below 50%.

It is essential to note that normal ranges may vary depending on the laboratory performing the test.

Results and Recommendations (Further Testing)

The interpretation of factor VIII test results may vary based on factors like age, gender, family medical history, and the laboratory conducting the test. Therefore, discussing your results with your doctor is essential.

Normal

A factor VIII activity level of 100% within the range of 50% to 150% is considered normal. To maintain good health, consume nutritious foods, engage in regular physical activity, and schedule periodic health checkups.

If you have symptoms of bleeding despite having normal or slightly reduced factor VIII levels, this may indicate von Willebrand disease. It is important to consult your doctor for further evaluation.

Abnormal

A decreased factor VIII activity level (below 50%) may indicate the following conditions:

• Hemophilia A: A genetic condition characterized by factor VIII deficiency.
• Disseminated Intravascular Coagulation (DIC): A condition causing widespread clotting and bleeding.
• Factor VIII Inhibitors: Antibodies that interfere with factor VIII activity.
• Von Willebrand Disease: A condition that affects blood clotting.

An increased factor VIII activity level (above 150%) may be associated with:

• Older Age
• Diabetes
• Liver Disease
• Inflammation
• Pregnancy
• Obesity

Elevated factor VIII levels can increase the risk of thrombosis, a condition in which blood clots form within blood vessels. In such cases, your doctor might suggest further tests and consider anticoagulant therapy to manage the risk.

Consult the Right Doctor

If your factor VIII test results are abnormal or indicate factor VIII deficiency, consult a general practitioner for an accurate diagnosis and appropriate treatment. You may also be referred to an internal medicine specialist for a more detailed evaluation and management of your condition.

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