Tempo di tromboplastina parziale attivato e carenza di precallicreina
Activated partial thromboplastin time and prekallikrein deficiency

AUTORI

ABSTRACT

Activated partial thromboplastin time and prekallikrein deficiency

Prekallikrein (PK) is a contact factor of the intrinsic pathway of the coagulation cascade. Patients with PK deficiency usually do not show bleeding tendency despite prolonged activated partial thromboplastin time (aPTT). Here we report two cases of male patients in their seventies, both with a prolonged aPTT detected at a pre-operative screening. 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. The aPTT test was then performed increasing the pre-incubation time of the patient’s plasma. This resulted in a significant shortening 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 obtained through a simple modification of the procedure of the aPTT test.

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