Final answer:
A Factor VIII assay is used to test for hemophilia A by measuring the activity level of Factor VIII in the blood, indicating the blood's clotting efficiency.
Step-by-step explanation:
The test for Factor VIII (VIII) in hemophilia, specifically hemophilia A, involves measuring the activity of Factor VIII in the blood. Hemophilia A is characterized by inadequate production of functional Factor VIII, which results in the blood's inability to clot effectively. To diagnose this condition, a healthcare provider will often perform a clotting factor test, sometimes referred to as a Factor VIII assay or activity test, to determine the level of activity of Factor VIII. This test is crucial in diagnosing hemophilia A and managing treatment, which may include regular infusions of clotting factors isolated from healthy donors or genetically engineered products.