In hemophilia, what laboratory finding is typically elevated?

In hemophilia, the laboratory finding that is typically elevated is the activated partial thromboplastin time (PTT). Hemophilia is a genetic disorder that affects the blood's ability to clot, primarily due to deficiencies in specific clotting factors—factor VIII in hemophilia A and factor IX in hemophilia B. These clotting factors are part of the intrinsic pathway of the coagulation cascade, which is assessed by the PTT.

When there is a deficiency in these factors, it leads to a prolonged PTT. This means that the time it takes for blood to clot is significantly increased, reflecting the underlying issue with the intrinsic pathway and the factors involved in that process.

In contrast, prothrombin time (PT) measures the extrinsic pathway and is typically normal in hemophilia patients unless there are other coagulopathies present. Bleeding time is primarily influenced by platelet function and is not notably affected in hemophilia, making it an unreliable indicator for this condition. Fibrinogen levels can be normal or slightly affected in hemophilia, as the primary defect revolves around the clotting factors rather than fibrinogen itself.

Thus, the elevation of PTT serves as a key laboratory indicator of hem