Summer 2005 - Research Project

Mikel Hubanks

Title of Project

Diagnostic utility of mixing studies in the evaluation of prolonged prothrombin times and activated partial thromboplastin times



Faculty Mentor

Richard Marlar, PhD

To further analyze the underlying cause of a prolonged clotting time, mixing studies are often used in the laboratory to differentiate a clotting factor deficiancy from a circulating clot inhibitul (lupus anti-coagulant or a specific inhibitor) to the test being performed. These results are then used to determine which confirmatory lab results should be allowed to determine whether a patient's sample is truly clotting-deficient or possesses a molecular inhibitor to the test being performed, thus yielding a false-positive prolonged test time. This study will assess the utility of a mixing study to correctly categorize plasm with prolong prothrombin times (PTTs) and activated partial prothrombin times (aPTTs) into a factur deficient or a circulating inhibitor.

To see if the time corrects or is only slighly reduced or minimal. If the time corrects, the patient has a factor deficient (or a specific factor inhibitor). If the time remains normal or is only slightly reduced, the patient possesses a specific inhibitor to the test (lupus anti-coagulant) and the time is falsely increased and the patient has normal clotting. The problem is the grey area between normal and abmormal clotting times. There are no general guidelines for labs across the world, and interpretations vary for normal values. Thus, a patient may test positive for factor deficient in one lab, while in another the mixing study may find the patient to possess a lupus anti-coagulant. Therefore, the results obtained from this study will hopefully be implemented into clinical practice by providing solid values to the mixing studies and avoid surgical complications.