The Coagulation Profile
A coagulation profile can include a number of blood tests that tell clinicians information about the clotting ability of blood. Typical tests done are called PT, aPTT, INR, Fibrinogen, and Platelets. Coagulation tests measure your body’s ability to form a clot. This is an important function when you are bleeding, but can be imbalanced due to illness, and you can have excessive bleeding which can lead to hemorrhage or excessive clotting which can lead to heart attack and stroke.
When you sustain an injury or break in the skin (the largest protector from our environment) your body immediately responds by sending substances to the area to reform a barrier or clot. There are many factors within our bodies that aid in clot formation, and they all need to be in the right balance for a healthy clot to form. This occurs in stages or phases and takes time. Hence some of the coagulation profile tests we will discuss measure the time it takes to form a clot or our bleeding time. Obviously, if bleeding time is delayed, this is not good as you are losing valuable blood and fluids, and can lead to serious consequences-hemorrhage or death.
Clinicians want to delay the body’s ability from forming clots too quickly in a case when a person has a problem with blood clots, to prevent clots from causing a heart attack or stroke. Blood clots that are out of balance will clog an artery, blocking circulation to the brain or heart. This can cause a heart attack or stroke, as well as tissue death to the area.
Bleeding and clotting is a delicate balance!
So let’s talk about some of the tests that make up a coagulation profile.
PT stands for prothrombin time. Prothrombin is a protein that our liver produces to aid in clotting. Our blood normally takes 25-30 seconds to clot, unless we are on blood thinners, and if Prothrombin time is too short or too long, well you get the picture, clotting is out of balance. Normal prothrombin time range is 10-14 seconds. Prothrombin also goes along with another blood test called an INR which stands for International Normalized Ratio (I know, sounds confusing). INR measures the amount of time it takes to form a clot. Results are given in a number of seconds. Another test that goes along with these is called the aPTT, which stands for activated partial thromboplastin time, another set of clotting factors. Sometimes these tests are used to monitor how well your body is responding to anticoagulation therapy such as with drugs like heparin or warfarin.
Thrombin time (TT), also known as the thrombin clotting time (TCT), is a blood test that measures the time it takes to form a clot in the plasma of a blood sample containing anticoagulant –“blood thinner” after an excess of thrombin has been added. Normal thrombin time range is 12-14 seconds.
A partial thromboplastin time (PTT) or activated partial thromboplastin test (aPTT) measures the time it takes to form a blood clot. Proteins in your blood called coagulation factors work together to form a blood clot. You have several coagulation factors in your blood. If any factors are missing or defective, it can take longer than normal for blood to clot. A PTT test checks the function of specific coagulation factors. Some of the factors include Factor VIII and IX associated with Hemophilia- (A bleeding disorder). Normal range for partial thromboplastin time is 30-45 seconds.
Fibrinogen is another protein substance made by the liver. It makes sense that if your fibrinogen is low, your body’s ability to clot blood can be affected, and if it’s too high it can cause clots to form out of balance.
Fibrinogen circulates in the blood waiting for the opportunity to help form a clot if we sustain an injury.
Fibrinogen can be too high in the cases of acute infections, heart disease, and cancer. The normal range is 200 to 400 mg/dL (2.0 to 4.0 g/L).
Platelets are also called thrombocytes, thromb meaning clot, and cyte meaning cell. Platelets circulate in our blood and clump together at the site of injury to form a clot. The National Institutes of Health consider a normal range of platelets to be between 150,000-400,000. If platelets are too low this is called thrombocytopenia. Some drugs can cause platelets to drop, and some illnesses can cause platelets to increase. Again, we don’t want these to be out of balance, which would cause too much clotting or not enough!
So how are all of these blood tests performed? The health care provider will order the test they want to monitor. It is done by a simple drawing of blood at a lab. Typically you do not need to abstain from eating or drinking prior to the test. The lab technician will cleanse the area for blood to be drawn. You will feel a pinch or a prick at the area when the needle is inserted into your vein. Pressure will need to be applied to the area after blood draw is complete to form a clot. You may wear a band-aid or cotton with tape for a while, and you may see a small mark or bruise on your skin that should heal within a few days.
If you are on medication and blood samples are being taken to monitor the effectiveness of drug therapy, you may have a blood test done more frequently to adjust medication or monitor progress. Time of day for testing may be a factor if your medication needs adjusting and your health care provider wants the test results before you take your next dose.
Some foods and medications may affect test results. Your health care provider will tell you what foods or medications to avoid prior to your blood test.
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