Quite often, with special laboratory tests, it is found that the patient has increased prothrombin time. What can this change indicate? How dangerous is this condition? Why do I need to determine prothrombin time, and to whom are these analyzes shown? These questions interest many.
What is prothrombin time?
It's no secret that blood coagulation processes are extremely important for the normal functioning of the human body. In addition, the blood contains specific factors that prevent increased coagulability, thereby preventing the formation of blood clots and clogging of blood vessels. The balance in the work of these two sections ensures the normal operation of all organ systems.
In order to understand what constitutes prothrombin time, you need to consider the general mechanism of coagulation. Damage to the vascular wall causes the activation of a special complex of enzymes that provide the formation of fibrin filaments. In turn, these threads become a sturdy frame for a blood clot, which. The blood coagulation system can be triggered in two ways - if the outer or inner layers of the vessel are damaged.
Thus, prothrombin time helps to find out how fast the blood coagulation system works with external activation.
Prothrombin time, INR and prothrombin index - what is it?
Naturally, the rate of blood coagulation in case of damage to the outer layers of the vascular wall is not an absolute indicator. By the way, PV should normally be from 11 to 16 seconds, and in order to get accurate data about the body, additional analyzes are needed.
In modern medicine, the international normalized ratio or INR is used. In such a study, the prothrombin time of the patient is compared with the same normalized plasma standard according to international standards. The formula is approximately as follows: patient's PV / PV of normalized plasma (the result is raised to the power of the so-called international thromboplastin sensitivity index).
The prothrombin index also determines the ratio of the PV of the control plasma to the PT of the patient's plasma, but in percentage. By the way, normally the index should be between 95 and 100%.
Quick's prothrombin time is by far the most accurate test. This study helps to compare the activity of the prothrombin complex of the patient with the indices of the control plasma.
Indications for research
In fact, there are many diseases and disorders that affect the process of blood coagulation. That is why such a study is carried out quite often. For example, it is prescribed to patients with suspected thrombosis. The analysis is also shown if the patient has found numerous hematomas and hemorrhages of unknown origin.
The same study is used in conjunction with several other procedures to evaluate liver function. If a deficiency or impaired vitamin K metabolism is suspected, patients are also sent for analysis. Prothrombin time is also determined in pregnant women, since this period of life is associated with some risks.
How are samples taken?
In order to determine prothrombin time, fresh plasma is needed. First, blood is taken from the patient. By the way, the samples in this case are taken from a vein, placed in a test tube with sodium citrate, which binds calcium ions.
In fact, some special preparation for testing is not required. They donate blood on an empty stomach, therefore, in most laboratories, blood sampling is carried out in the morning (up to 11 hours). Most likely, you will receive the test results the very next day. It is also worth noting that some factors can distort the results, so be sure to consult your doctor before testing.
How is prothrombin time determined in laboratory conditions?
Determination of prothrombin time is a relatively simple procedure. As already mentioned, after sampling, the blood is mixed with potassium citrate and delivered to the laboratory. Next, the sample is mixed and placed in a centrifuge at a temperature of 37 ° C. After this, the required amount of calcium is added to the sample, and then the tissue coagulation factor . Then, the time during which a blood clot forms is detected. As already mentioned, it should be 11-16 seconds.
Performance enhancement
If prothrombin time is increased - is it dangerous? Unfortunately, the test results do not always correspond to the normal value. What disorders increase prothrombin time?
- There are some congenital diseases accompanied by a deficiency of blood coagulation factors.
- In some cases, insufficient coagulation factors are acquired. In particular, a similar condition is observed in a number of autoimmune diseases and amyloidosis.
- A similar change in PV is observed in diseases of the liver and liver failure.
- The cause may also be DIC.
- With developing hypovitaminosis K, prothrombin time is also increased. In turn, a deficiency of this vitamin can be observed with dysbiosis, malabsorption syndrome, as well as some diseases of the gallbladder and pancreas.
- The increase in PV leads to the intake of certain anticoagulants.
- Massive blood transfusion can also affect the results of the study.
If the rate is lowered
In some patients, the prothrombin time is reduced - a blood clot (blood clot) forms much faster than required. This is also a dangerous condition, which is fraught with the development of blockage of blood vessels.
Quite often, a decrease in PV indicates the presence or risk of thrombosis, which is extremely dangerous, since it is often a threat to the patient's life. A decrease in the indicator is often associated with the intake of certain groups of hormonal contraceptives. Polycythemia may also be the cause. In pregnant women, blood coagulates much faster in the third trimester of pregnancy.
What can affect the reliability of analyzes?
It is immediately worth noting that there are many factors that, to one degree or another, can affect the result of the analysis. As already mentioned, taking anticoagulants and certain hormonal drugs can increase the duration of a blood clot. But there are some other limitations.
In particular, the results of the study will be false if you take aspirin, barbiturates, medicines containing vitamin K. In addition, some groups of antibiotics also affect prothrombin time.
Digestive problems can also affect the results of the analysis. In particular, prolonged diarrhea or frequent vomiting leads to dehydration. In addition, with such disorders, the absorption of vitamins and minerals, including tocopherol (vitamin K), is disrupted.
If you consume foods that contain large amounts of vitamin K, the test results may not be accurate. A few days before the analysis, limit the amount of pork and beef liver, soy products, peas, green tea, cabbage, greens and broccoli.
Alcohol abuse also affects the blood coagulation process, therefore, again, a few days before testing, alcohol should be discarded.
Factors affecting PV include laxative medications and some homeopathic medicines.
If you are taking any medications, be sure to inform your doctor. Tell the specialist about the features of your diet and the health problems that are present. Otherwise, the analysis will not be informative, and the doctor may prescribe completely inappropriate drugs.
Why determine prothrombin time for a pregnant woman?
It’s no secret that during the gestation of a child, the woman’s body (especially the circulatory and endocrine system) undergoes significant changes. That is why determining prothrombin time during pregnancy is extremely important.
In some women, blood coagulation increases during this period, which leads to thrombosis and blockage of blood vessels that carry blood to the child’s body. In the absence of timely treatment, such a violation can lead to DIC and even fetal death.
On the other hand, during pregnancy, blood can also liquefy too much. In such cases, there is a high risk of massive blood loss, especially during childbirth. Determination of prothrombin time allows the doctor to identify a violation in time and prevent the development of complications.