Prolungamento del tempo di tromboplastina parziale attivata in una paziente asintomatica: la carenza di precallicreina
1Dipartimento di Scienze, Università di Roma Tre, Roma
2UOSD Patologia Clinica, Istituto Nazionale Tumori "Regina Elena", Roma
Prolonged activated partial thromboplastin time in an asymptomatic patient: the prekallikrein deficiency
Prekallikrein (PK) is a contact factor of the intrinsic pathway of the coagulation cascade. Patients with PK deficiency usually do not show a bleeding tendency despite a prolonged activated partial thromboplastin time (aPTT) test. Here we report a case of a 72-years-old Caucasian woman manifesting a prolonged aPTT test. The aPTT correction after 1:1 mixing with normal pool plasma (NPP) indicated a coagulation factor deficiency; however factors XII, XI, IX and VIII activities were normal. A 100:1 mixing with NPP was performed, resulting in an aPTT test correction; the aPTT test was then performed increasing the pre-incubation time of the patient’s plasma. This resulted in a significant reduction of the aPTT. The PK deficiency was ultimately confirmed by direct measurement of PK plasma activity. This experience shows that PK deficiency should be considered for asymptomatic patients with prolonged aPTT and that, whenever a PK deficient plasma is not available, the diagnosis can be correctly oriented on the basis of simple aPTT tests.