Phlebology Research Lab: Specialised Tests

Haemostasic disorders have several causes. Rather chronic processes (such as comorbidities of the haemostasis-related organs liver-kidney-bone marrow) or hereditary diseases can be differentiated from acute alterations due to trauma, haemodilution and the current treatment. The resulting alterations affect the plasmatic coagulation factors, platelets and the fibrinolytic system. Thromboelastography was developed for the management of acute bleeding. The ROTEM is an enhancement of thromboelastography and includes measurement channels for simultaneous determinations, an integrated computer for automatic analysis and an electronic pipette for interactive test operation. Various activators or inhibitors are added to the sample, in order to represent different processes of haemostasis.

Multiplate Analyser
The Multiplate Platelet Function Analyser assesses within 15 minutes the platelet funtion in whole blood and platelet rich plasma. Multiplate is an abbreviation for multiple platelet function analyser, which provides multiple test channels, multiple tests as well as two sensor devices in each measuring cell. Several reagents are available to allow triggering of different receptors/signal transduction pathways of the platelet in order to detect its function or drug effects. Impedance aggregometry is based on the principle that blood platelets are non-thrombogenic in their resting state, but exposed receptors on their surface when they get activated which allow them to attach on vascular injuries and artificial surfaces.
When platelets stick on the Multiplate sensor wires, they enhance the electrical resistance between them, which is continuously recorded. Using the different test procedures of the Multiplate comprehensive information on platelet function and anti-platelet therapy is obtained.

Procoagulant phospholipid (PPL) is important for the efficient interaction of various blood coagulation factors to form factor Xa, thrombin and ultimately a fibrin clot at a wound site. PPL in vitro has little effect on conventional clotting tests such as the PT or APTT because such reagents normally contain high levels of phospholipid so as to minimize the effect of variations in platelet count in plasma specimens.
PPL in vivo is thought to be mainly provided by platelets localised to and activated at a site of injury. Activated platelets usually aggregate but can also release PPL-rich microparticles of various size, which are detectable in circulation. PPL is expressed in vitro when platelets are activated or damaged by freeze thawing.
The time it takes for recalcified normal plasma to clot after addition of a given amount of factor Xa is inversely related to the concentration of procoagulant phospholipid, factor V and prothrombin in the test system. Deficiencies of any of these components or the presence of inhibitors prolong the clotting time.
This new XACT test is specific for PPL because the test sample is mixed with phospholipid-deficient animal plasma and this provides excess factor V and prothrombin. It also corrects most other defects in a test specimen. A heparin neutraliser in the XACT reagent confers resistance to at least 5 units/ml of regular heparin. The XACT clotting time is thus inversely related only to the PPL concentration. The system can be calibrated with the reference phospholipid provided or with plasmas containing known concentrations of activated platelets. All consumables for XACT tests can be found at Haematex Research.

D-dimer test
We take blood for D-dimer test and send the samples to Sydpath. D-dimer may be ordered when a patient has undergone sclerotherapy in order to exclude a Deep Vein Thrombosis (DVT). It is a quick, non-invasive way to help rule out abnormal or excess clotting.