Acquired haemophilia A: errors in the diagnosis.

Abstract

The distinction between a specific factor inactivator and a non-specific inhibitor is important when confronted by a patient with a history of bleeding and abnormal in-vitro coagulation tests. We report on two patients who presented with bleeding and a prolonged activated partial thromboplastin time. Initial factor assays suggested combined deficiency of factors VIII and IX as a result of the presence of inactivators. The use of dilution studies, chromogenic assays, a novel in-house enzyme-linked-immunosorbent-assay-based technique and phospholipid neutralization, demonstrated that Case 1 had a genuine factor VIII inactivator resulting in factor VIII levels of less than 1 IU/dl but no factor IX deficiency. Case 2 had normal levels of factor VIII on further testing and no specific inactivator to either factor VIII or IX but a potent antiphospholipid antibody which had interfered with the phospholipid-dependent in-vitro assays. Care must be taken in the interpretation of laboratory assays in the presence of antiphospholipid antibodies to ensure that the correct diagnosis is made and inappropriate treatment avoided.

• Authors: M A Kazmi, W Pickering, M P Smith, L J Holland, G F Savidge
• Journal: Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis (Blood Coagul Fibrinolysis) Vol. 9 Issue 7 Pg. 623-8 (Oct 1998) ISSN: 0957-5235 [Print] England
• PMID: 9863711 (Publication Type: Case Reports, Journal Article)

Chemical References

• Antibodies
• Antibodies, Antiphospholipid
• Factor VIII
• Factor IX

Topics

• Adult
• Aged
• Antibodies (immunology)
• Antibodies, Antiphospholipid (immunology)
• Diagnosis, Differential
• Factor IX (immunology)
• Factor VIII (immunology)
• Female
• Hemophilia A (blood, diagnosis, immunology)
• Humans
• Immunoassay (methods)
• Lupus Erythematosus, Systemic (blood, diagnosis, immunology)
• Male
• Sensitivity and Specificity