- - - Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
- - - Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
- - - Department of Hematology and Oncology, School of Medicine, Iran University of Medical Science, Tehran, Iran

Hereditary deficiency of plasma prekallikrein (PPK) is a rare autosomal recessive disease. The affected patients are often asymptomatic and diagnosed incidentally during preoperative investigations or during hospitalization by isolated prolongation of activated partial thromboplastin time (aPTT). In this article, we report, a ۴۶-year-old woman who was candidate for two invasive procedures (thyroid FNA and hysterectomy) and underwent preoperative evaluation.  Due to prolonged aPTT with normal PT she was referred to the IBTO reference coagulation laboratory for specific coagulation assays. Ultimately, the examinations revealed severe PPK deficiency (<۱%) with partial deficiency of factor XII level (۲۵%).

Factor XII deficiency, Prekallikrein deficiency, Prolonged aPTT