A dyspnea patient with abnormal prolonged prothrombin time and activated partial thromboplstin time, but without bleeding symptoms.

A patient with erythrocytosis secondary to chronic obstructive pulmonary disease (COPD) was admitted to hospital because of dyspnea. The coagulation tests revealed abnormal prolonged prothrombin time (PT) and activated partial thromboplstin time (APTT), however, it could not be explained by the patient's medical history or physical signs of coagulation disorder. High hematocrit (Hct), which leads to reduced plasma-to-anticoagulant rate and increased final plasma anticoagulant concentration, was identified as the reason for false prolongation of PT and APTT.