Diagnostic Pearls and Clinical Implications of Prekallikrein Deficiency.

Prekallikrein (PK) deficiency is extremely rare, and manifestations are not well characterized due to a small number of cases reported and the lack of scientific clarity about its role in clot formation in vivo. Here, we report a case of a 64-year-old male, with no known history of abnormal bleeding, who scheduled to undergo deep brain stimulator placement for control of his Parkinson's disease. During pre-procedure testing, activated partial thromboplastin time (PTT) was found to be prolonged at 146 seconds. Mixing studies were suggestive of a coagulation factor deficiency. His PTT characteristically became shorter with prolonged incubation, providing a clue at testing for PK levels, which were found to be severely low. He, subsequently, underwent surgery without any complications. Our case further highlights the clinical pearls for diagnosis and further endorses that these patients can safely undergo surgical procedures without the need for plasma transfusions or factor concentrate usage.