Activated partial thromboplastin time prolongation

II Umbilical cord, joint, and mucosal tract bleeding Prolonged prothrombin (PT) and activated partial thromboplastin time (aPTT) Specific assay for prothrombin... 

Activated partial thromboplastin time aPTT is performed by adding calcium phospholipids and kaolin to citrated blood and measures the time required for a fibrin clot to form. In this manner, aPTT measures the activity of intrinsic and common pathways. Prolongation of aPTT may be due to a deficiency or inhibitor for factors II, V, VIII, IX, X, XI, and XII. It also may be due to heparin, direct thrombin inhibitors, vitamin K deficiency, liver disease, or lupus anticoagulant. 

Therapy with heparin occurs in an inpatient setting. Heparin inhibits both in vitro and in vivo clotting of blood. Whole blood clotting time and activated partial thromboplastin time (aPTT) are prolonged in proportion to blood heparin concentrations. 

E. Therapeutic response Intravenous bivalirudin produces a rapid and dose-dependent prolongation of the activated partial thromboplastin time (aPTT), prothrombin time, activated clotting time (ACT), and thrombin time. 

The indications for the use of heparin are described in the section on clinical pharmacology. A plasma concentration of heparin of 0.2-0.4 unit/mL (by protamine titration) or 0.3-0.7 unit/mL (anti-Xa units) usually prevents pulmonary emboli in patients with established venous thrombosis. This concentration of heparin will prolong the activated partial thromboplastin time (aPTT) to 2-2.5 times that of the control value. This degree of anticoagulant effect should be maintained throughout the course of continuous intravenous heparin therapy. When intermittent heparin administration is used, the aPTT should be measured 6 hours after the administered dose to maintain prolongation of the aPTT to 2-2.5 times that of the control value. 

Asymptomatic prolongation of the activated partial thromboplastin time associated with Inpus anticoagulant and a reduction in the coagulation activity of factors IX, XI, and XII occurred after 10 weeks of interferon alfa-2b and ribavirin in a 60-year-old woman with chronic hepatitis C (236). There were no arguments in favor of an antiphospholipid syndrome, and all the abnormalities normalized after withdrawal. 

Several new compounds have been reported that affect the formation of a fibrin clot. Aromatic diamidines, such as, 21, were reported to inhibit several proteolytic enzymes including thrombin.74 Concanavalin A (a globulin protein from the jack bean) inhibits fibrin formation by inhibiting the lipoprotein cofactor in the production of thrombin and thus decreasing the rate of thrombin production.75 Several antibiotics (penicillins and cephalosporins) have been reported to affect fibrin clot formation as well as platelet function. Cephalothin (22) has been shown to delay fibrin polymerization and thus prolong the activated partial thromboplastin time (APTT) and thrombin time tests.78... 

Reduced side-effects compared to PT-based ODN In contrast to PT-based CpG-ODN, dSLIM induced no liver and spleen enlargements after 7 days of consecutive intraperitoneal injection into mice. Both molecule groups were compared regarding equal mass and molarity. Furthermore, PO-based dSLIM do not significantly prolong the activated partial thromboplastin time (aPTT), as reported previously for PT-based ODN. 

Hepatic injury can also alter the synthesis of the blood coagulation cascade and prolong prothrombin and activated partial thromboplastin times. These effects on vitamin K dependent coagulation factors II (prothrombin), VII, IX, and X and protein C, protein S, and protein Z tend to affect the prothombin time (PT) more frequently than the activated partial thromboplastin time (APTT) however in some cases of hepatotoxicity, the APTT changes may be more marked than those for PT (Pritchard et al. 1987). 

PVS was grafted onto the surface of polyurethane, polystyrene, and poly(ethylene terephthalate) films by the plasma-pietreated method. Activated partial thromboplastin time (APTT) of PVS-grafted polyurethane films was greatly prolonged, and a fibrin network was not found at on the film grafted with PVS in... 

Sodium xylan polysulphate, an artificially sulphated (1 4)- 3-D-xylan, has been shown to prolong the partial thromboplastin clotting time of plasma. The differential effects of xylan sulphate on different blood serine proteases were discussed in terms of the antithrombin Ill-mediated anticoagulant activity of heparin. 

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