Partial thromboplastin time (PTT) is done to: Find a cause of abnormal bleeding or bruising. Check for low levels of blood clotting factors. The lack of some clotting factors can cause bleeding disorders such as hemophilia. Check for conditions that cause clotting problems. Conditions such as antiphospholipid antibody syndrome or lupus anticoagulant syndrome develop when the immune system makes antibodies that attack blood clotting factors. This can cause the blood to clot easily in veins and arteries. Check if it is safe to do a procedure or surgery that might cause bleeding. Check how well the liver is working. The activated partial thromboplastin time (APTT) test is used after you take blood-thinners to see if the right dose of medicine is being used. If the test is done for this purpose, an APTT may be done every few hours. When the correct dose of medicine is found, you will not need so many tests.
In this test PTT of the patient is measured. A prolonged aPTT result may indicate the following [1, 2] :
Congenital deficiencies of intrinsic system clotting factors such as factors VIII, IX, XI, and XII, including hemophilia A and hemophilia B (Christmas disease), two inherited bleeding disorders resulting from a deficiency in factors VIII and IX, respectively
Congenital deficiency of Fitzgerald factor (prekallikrein)
Von Willebrand disease, which is the most common inherited bleeding disorder, affecting platelet function owing to decreased von Willebrand factor activity
Liver cirrhosis (the liver makes most of the clotting factors, including those that are vitamin K-dependent ones); diseases of the liver may result in an inadequate quantity of clotting factors, prolonging the aPTT
Vitamin K deficiency: The synthesis of some clotting factors requires vitamin K, so vitamin K deficiency results in an inadequate quantity of intrinsic system and common pathways clotting factors, as a result the aPTT is prolonged. A shortened aPTT result may indicate the following [1, 2] :
Early stages of DIC: circulating procoagulants exist in the early stages of DIC, shortening the aPTT
Extensive cancer (eg, ovarian cancer, pancreatic cancer, colon cancer)
Immediately after acute hemorrhage
An acute-phase response leading to high factor VIII levels.
Blood tests are normally well-tolerated. Some people have smaller or larger veins, which may make taking a blood sample more difficult. However, risks associated with blood tests like the ACTH hormone test are rare. Uncommon risks of having blood drawn include: excessive bleeding lightheadedness or fainting hematoma, or blood pooling under the skin infection at the site
Depending on the cause, a few things may be done to lower the risks of developing recurrent blood clots. Measures may include avoiding the use of oral contraceptives if you have other inherited or acquired risk factors and avoiding situations that cause prolonged sitting or confinement to bed.
Regardless of the cause, the treatment for the presence of a blood clot (acute thrombosis) is often fairly standard. It usually consists of short-term treatment with the anticoagulant heparin (or, more commonly, low-molecular weight heparin), followed by an overlap of treatment with heparin and oral warfarin (COUMADIN®), another anticoagulant, followed by several months or longer of warfarin therapy. During this treatment regimen, laboratory tests are used to monitor the effectiveness of therapy:
Unfractionated (standard) heparin is monitored using the PTT or occasionally heparin anti-Xa assay.
Low molecular weight heparin (LMWH) is monitored with the heparin anti-Xa test if monitoring is needed.
Warfarin therapy is monitored with the PT/international normalized ratio (INR) or occasionally factor X activity assay.