Prothrombin Time (Index) Low: Possible Interpretations of Test Results

Some people who do medical tests regularly or before necessary surgery may come across a strange result indicating a low prothrombin index.

What can it mean and what to do in this case?

Let's explore the details.

What is Prothrombin Time (PT)?

This test helps a doctor to evaluate blood’s ability to clot. Often patients do it before surgery, as using its results healthcare professionals may forewarn possible issues related to improper blood clotting and bleeding after surgical intervention.

Prothrombin is one of the plasma proteins involved in the process of blood coagulation. It is also called factor II. It is a progenitor of thrombin and therefore has the name '[pro]thrombin.'

When the amount of prothrombin corresponds to the physiological norm, dangerous blood clots do not form in the blood vessels, and bleeding after small wounds stops in due time. If it is very low, it can take a long time for the bleeding to remain.

For example, a patient may suffer from unstoppable bleeding after his / her wisdom tooth is removed.

The prothrombin index (time) is indicated in ratios or simply percent and means the ratio between the real coagulation time of a particular blood sample and the reference indicator in healthy patients, the so-called international normalized ration (INR).

Prothrombin index is measured in seconds and the normal range is 11 to 13.5 secs.

This corresponds to approximately 0.8 to 1.1 INR. Deviations may indicate health conditions/disorders, but not always, as blood tests sometimes may indicate incorrect results, in particular, due to uncapped or expired collection tubes, partially clotted specimens, and some other factors. So repeated test may shed the light on the actual condition.

Possible Causes of Lowered Prothrombin Time

Taking warfarin (brand names Coumadin, Jantoven, Apo-Warfarin etc.) is the most common cause of the condition. This medication is a highly popular blood thinner which is used to treat blood clots associated with vein thrombosis and pulmonary embolism (PE). This is also a preventive drug that helps to avert stroke in individuals with cardiovascular diseases. It should be noted that Warfarin is vitamin K antagonist, and this factor is linked to the cause described below.

Another common cause of decreased PT is vitamin K deficit which is associated with improper diet. This essential fat-soluble substance is used by the body to help blood clot. Its name 'K' has been derived from Danish ‘koagulation’ which means ‘coagulation’, because the nutrient is paramount for clotting processes.

Other potential causes include:

• hormonal problems
• intestinal disorders that make it difficult for vitamin K to enter the bloodstream
• a general deficiency of proteins in the blood, and in particular fibrinogen
• deficiency of proteins like fibrinogen in the blood
• administration of some oral contraceptives
• disseminated intravascular coagulation (a severe health issue which needs immediate treatment)
• hormone replacement therapy
• intake of oral contraceptives which are based on hormone-like substances

Some Scientific Pieces

According to a study by V. Croquet, E. Vuillemin et al. (European Journal of Gastroenterology & Hepatology, 2002), low PI is an indirect marker of severe liver fibrosis. [link]

As stated by K. Weigand, J. Encke and others (Medizinische Klinik Munich, 2009), low levels of prothrombin index and platelets don’t increase the risk of significant bleeding when placing central venous catheters during cannulation. [link]

What to Do?

It is necessary to identify the cause and proceed to treatment. If coagulants (drugs that increase blood coagulation) are needed, your doctor will certainly prescribe them and tell you how to take them properly.

If you have been diagnosed with vitamin K deficiency, you need to nourish the organism with it naturally or by intake of appropriate supplements.

The most known natural sources of the vitamin include:

• green leafy veggies (spinach, parsley, Swiss chard, romaine, lettuce, and dill)
• vegetables (broccoli, Brussels sprouts, cabbage)
• eggs and fish, liver, cereals (not too rich sources)

Chlorophyll is a healthful supplement which is packed with various vitamins and minerals. It can contribute to normalization of PT parameters.

Anyway, take appropriate measures and take blood tests repeatedly. Lowered T may be a sign of some diseases -- here’s why it is important to find the underlying cause, eliminate it, and normalize blood clotting indicators in your body.