Stollingsonderzoek: PT en APTT
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Labquiz
30-01-2012
Christian Ramakers, Cees van der Heul en Eduard M. van Wijk

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.

Conflict of interest: none declared. Financial support: none declared.