Hemophilia A laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory Findings
The diagnosis may be suspected as coagulation testing reveals an increased PTT in the context of a normal PT and bleeding time. The diagnosis is made in the presence of very low (<10 IU) levels of factor VIII. A very small minority of patients has antibodies against factor VIII that impair its functioning. Management of these patients is more complicated.
- Prolonged partial thromboplastin time (PTT)
- Normal prothrombin time
- Normal bleeding time
- Normal fibrinogen level
- Low factor VIII
Other laboratory findings consistent with the diagnosis of hemophilia A include correction of the PTT with a 1:1 mixing study (i.e. factor VIII from the normal blood mixed with the hemophiliac blood is able to correct for the coagulation deficit)