[Investigation of coagulation time: PT and APTT].
The first case report describes an extremely prolonged activated partial thromboplastin time (APTT) in a patient with no history of increased bleeding tendency. Heparin use was excluded. The APTT mixing study combined with the medical history suggests a deficiency in one of the non-essential coagulation factors. This was confirmed by factor XII activity of <1%. The second case report describes a prolonged APTT in a patient with no history of increased bleeding tendency. The negative bleeding tendency in combination with a failure of the mixing study to correct the coagulation assay results suggests a factor inhibitor, most probably lupus anticoagulant. Indeed, the lupus anticoagulant was positive and the anti-cardiolipin antibody titre was also positive. Aberrations in the process of haemostasis can be efficiently screened using a platelet count, an APTT, a PT and a thorough physical examination combined with a thorough medical history taking. Common causes of prolonged PT and/or APTT are the use of oral anticoagulants or heparin, vitamin K deficiency and liver disease. Other causes include coagulation factor deficiencies, coagulation factor inhibitors and diffuse intravascular coagulation.
Sint Elisabeth Ziekenhuis, Afd. Klinisch Chemisch en Hematologisch Laboratorium en Trombosedienst, Tilburg, the Netherlands. c.ramakers@erasmusmc.nl
Christian
C
Ramakers
Cees
C
van der Heul
Eduard M
EM
van Wijk
D000368:Aged; D001777:Blood Coagulation / Q000502:physiology*; D001778:Blood Coagulation Disorders / Q000175:diagnosis* / Q000209:etiology; D001779:Blood Coagulation Factors / Q000032:analysis*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010314:Partial Thromboplastin Time / Q000706:statistics & numerical data*; D011517:Prothrombin Time / Q000706:statistics & numerical data*
D001779:Blood Coagulation Factors