Abstract
In a patient with congenital afibrinogenemia, prolonged bleeding time is thought to be related to the defective platelet aggregation induced by ADP or poor platelet adhesiveness to glass beads.
Our recent study revealed that the patient's platelets can adhere to subendothelium normally but cannot form thrombi on it.
Accordingly, in a patient with congenital afibrinogenemia we attempted to observe the role of fibrinogen that influenced on platelet adhesion to subendothelium (SE) and thrombus formation on the SE by using Baumgartner's method at various levels of fibrinogen. Fibrinogen was transfused to the patient and the platelet adhesion to SE, thrombus formation, ADP induced platelet aggregation and bleeding time were observed. We also carried out in vitro addition of fibrinogen to the patient's blood samples and observed the platelet adhesion to SE and thrombus formation. The range of fibrinogen in the experiments varied from 0.07mg/dl to 110mg/dl.
Our results revealed that the platelet adhesion to SE was normal. On the other hand, thrombus formation was poor when the level of fibrinogen was between 0.07mg/dl and 1mg/dl. However, it was normalized when the level of fibrinogen was crossed over the level of 2.5mg/dl. This level of fibrinogen was almost equal to the level of fibrinogen that corrected the prolonged bleeding time or defective ADP (2μM) induced platelet aggregation.
This study suggested that the lowest level of fibrinogen consistent with normal platelet function in a patient with congenital afibrinogenemia was about 2.5mg/dl.
