History

You are asked to consult on a 72 year-old woman who was admitted to hospital with a stroke and was found to have an elevated activated partial thromboplastin time (aPTT). She had presented 2 days earlier to the emergency room with new onset dysarthria and hand numbness. Imaging revealed a small right frontal/parietal cortical stroke. She was started on low dose aspirin. Work-up by the neurology service revealed an elevated aPTT of 66.7 seconds, with a normal prothrombin time of 12. 1 seconds. The last recorded aPTT on file was 31 seconds 5 years earlier. Other active medical problems include hypertension, hypothyroidism and bicuspid aortic valve. She had a previous thymectomy for a benign mass. She has no family history of hematological conditions. She is a non-smoker and drinks socially. She is a retired librarian. Home medications include levothyroxine and metoprolol. She has no known allergies.