In severe hemophilia, the factor VIII level is typically below which threshold?

In severe hemophilia, the factor VIII level is typically below which threshold?

• A. <1%
• B. 1-5%
• C. 6-30%
• D. >30%

Answer: (A)

The key idea is how factor VIII activity defines the severity of hemophilia. In severe hemophilia A, the factor VIII activity is below 1% of normal. With such very low levels, the intrinsic coagulation pathway can’t form thrombin effectively, leading to spontaneous bleeding and significant bleeding with minor trauma. That threshold (<1%) distinguishes severe from the moderate range (about 1–5%) and the mild range (roughly 5–40%). So the typical value for severe disease is below 1%, which is why this option is the best choice.

The key idea is how factor VIII activity defines the severity of hemophilia. In severe hemophilia A, the factor VIII activity is below 1% of normal. With such very low levels, the intrinsic coagulation pathway can’t form thrombin effectively, leading to spontaneous bleeding and significant bleeding with minor trauma. That threshold (<1%) distinguishes severe from the moderate range (about 1–5%) and the mild range (roughly 5–40%). So the typical value for severe disease is below 1%, which is why this option is the best choice.