Laboratory Values

A prolonged partial thromboplastin time (PTT) indicates the need to perform specific coagulation factor assays. Diagnosis is confirmed by a low or absent factor VIIIc or factor IX. Normal factor VIIIc and factor IX levels range from 50% to 150%. If the family history is positive for hemophilia, however, or if a clinical suspicion of hemophilia exists, a factor assay should be performed.

Factor Deficiency Table
Factor VIII Deficiency Factor IX Deficiency
Test Result Test Result
PT Normal PT Normal
PTT Prolonged PTT Prolonged
BT Normal BT Normal
Factor VIIIc Low Factor IX Low