Which results are associated with hemophilia A?

Hemophilia A is a genetic disorder caused by a deficiency in clotting factor VIII, which is essential for the proper functioning of the intrinsic pathway of the coagulation cascade. One of the key laboratory tests used to assess coagulation is the activated partial thromboplastin time (APTT), which evaluates the intrinsic pathway of the coagulation process, including the function of factor VIII.

In hemophilia A, because factor VIII is specifically deficient, the APTT is prolonged as it takes longer for blood to clot. However, the prothrombin time (PT), which assesses the extrinsic pathway and involves factors such as VII and X, remains normal because these factors are not affected by the absence of factor VIII. Therefore, in the context of laboratory findings for hemophilia A, a prolonged APTT with a normal PT is characteristic.

This combination of test results aligns specifically with the behavior of hemophilia A, making the identification of such patterns crucial for accurate diagnosis and management of the condition.