凝血酶原时间(PT)

定义

凝血酶原时间(PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. It measures the function of a part of the clotting system.

一项相关的血液检查是 部分凝血活素时间, which measures the function of a different part of the clotting system.

选择的名字

PT; Pro-time; Anticoagulant-prothrombin time; Clotting time: protime; INR; International normalized ratio

如何执行测试

A 需要血液样本. 如果你 是 taking blood-thinning medicines, you will be watched for signs of bleeding.

如何准备考试

Certain medicines can change blood test results.

• Your health c是 provider will tell you if you need to stop taking any medicines before you have this test. This may include aspirin, heparin, antihistamines, and vitamin C.
• DO NOT stop or change your medicines without talking to your provider first.

Also, tell your provider if you're taking any herbal remedies.

考试的感觉如何

When the needle is inserted to draw blood, some people feel moderate pain. 其他人只感到刺痛或刺痛. Afterward, there may be some throbbing or slight bruising. 这很快就会消失.

为什么要进行测试

The most common reason to perform this test is to monitor your levels when you 是 taking a blood-thinning medicine called 华法令阻凝剂 (香豆素). You 是 likely taking this medicine to prevent blood clots.

Your provider will check your PT regularly to monitor and adjust the dose of 华法令阻凝剂.

你也可能需要这个测试来:

• Find the cause of abnormal bleeding or bruising
• 检查一下肝脏的工作情况
• 寻找血液凝固的迹象或者 凝血障碍

正常的结果

PT以秒为单位测量. Most of the time, results 是 also given as what is called INR (international normalized ratio).

如果你 不 taking blood thinning medicines, 比如华法林, the normal range for your results is:

• PT = 11 ~ 13.5秒
• INR为0.8 to 1.1

如果你 是 taking 华法令阻凝剂 to prevent blood clots, your provider will most likely choose to keep your INR from 2.0 to 3.0.

Ask your provider what result is right for you.

Normal value for PT ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples.

异常结果意味着什么

如果你 不 taking blood thinning medicines, 比如华法林, an INR result above 1.1 means your blood is clotting more slowly than normal. 这可能是由于:

• 出血失调, a group of conditions in which there is a problem with the body's blood clotting process.
• Disorder in which the proteins that control blood clotting become over active (disseminated intravascular coagulation).
• 肝脏疾病.
• 低水平 维生素K.

如果你 是 taking 华法令阻凝剂 to prevent clots, your provider will most likely choose to keep your INR from 2.0 to 3.0:

• Depending on why you 是 taking the blood thinner, the desired level may be different.
• 当你的印度卢比从2.0 to 3.0, you 是 more likely to have bleeding problems.
• INR结果高于3.0 may put you at even higher risk for bleeding.
• INR结果低于2.0 may put you at risk for developing a blood clot.

A PT result that is too high or too low in someone who is taking 华法令阻凝剂 (香豆素) may be due to:

• 用药剂量不对
• 喝酒
• Taking certain over-the-counter (OTC) medicines, 维生素, 补充, 感冒药, 抗生素, 或者其他药物
• Eating food that changes the way the blood-thinning medicine works in your body

Your provider will teach you about taking 华法令阻凝剂 (香豆素) the proper way.

风险

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn 是 slight, but may include:

• 昏厥或感到头晕
• Hematoma (blood accumulating under the skin)
• 多次穿刺定位静脉
• Infection (a slight risk any time the skin is broken)

This test is often done on people who may have bleeding problems. Their risk of bleeding is slightly higher than for people without bleeding problems.

参考文献

李·GM，奥特尔·TL. 抗凝治疗. 见:McPherson RA, Pincus MR，编辑. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24日艾德. Philadelphia, PA: Elsevier; 2022:chap 43.

谢弗艾. Approach to the patient with bleeding and thrombosis. 参见:Goldman L, 谢弗艾主编. Goldman-Cecil医学. 26日艾德. Philadelphia, PA: Elsevier; 2020:chap 162.