Activated partial thromboplastin time (APTT) is a special medical test that simulates the process of clotting blood on the inner way, aimed at assessing the presence of plasma factors, inhibitors and anticoagulants in the blood.
It shows the effectiveness of the internal mechanism of blood clotting, allows to diagnose hemophilia and monitor patients undergoing heparin and herdin therapy.
For an adult, the norm of APTTV is from 21 to 35 seconds. Elongation of APTTV means that the blood is curled more slowly than necessary. This happens in those cases when there are not enough clotting factors in the blood, or there are substances in the plasma that slow blood coagulation.
It should be remembered that different equipment in the laboratory has its own specific norms. When you receive a result, this indicator will be indicated in the column "reference values".
AHTTV - what is it?
AChVT is the period of time for which a blood clot appears, this occurs after calcium chloride or other reagents are added to the plasma. At the moment, the analysis is the most accurate indicator, the presence of diseases associated with blood clotting
Basicindications for the appointment of AChVT:
- Diagnosis of hemophilia;
- General assessment of the blood coagulation system (identification of the causes of thrombosis and bleeding;
- DIC-syndrome (a syndrome of disseminated intravascular coagulation);
- Monitoring of anticoagulant therapy (heparin treatment);
- Detection of the deficiency of coagulation factors along the internal pathway: II, V, VIII, IX, X, XI, XII.
Normally, the fibrin clot forms within 21-35 sec. Methodology of researchconsists in the following manipulations:
- The venous blood is drawn into a tube containing sodium citrate, which has the ability to bind calcium ions responsible for clotting of blood.
- After this, reagents are added to the tube, which activate the internal way of blood coagulation. As a reagent, the most commonly used are koalin or kefalin.
- The next step in the study is the addition of calcium chloride to the tube, to neutralize the anticoagulant effects of sodium citrate and restoration of hemostasis, and evaluation of the rate of clot formation.
Before the study should adhere to such recommendations as a temporary refusal to take anticoagulant drugs, hunger for 12 hours before the analysis and, if possible, quitting during the day.
The causes of increased or decreased APTT
If the APTTV exceeds the norm, this indicates that the patient has possible liver diseases or a deficiency vitamin K in the body, and this can also speak of the presence of a vocal anticoagulant in the blood.
If the indicators are lower than normal, this may be due to a decrease in blood clotting, the presence of hemophilia and antiphospholipid syndrome. In addition, this deviation from the norm may be associated with intravascular coagulation syndrome. A low APTT is a symptom of intravascular coagulation, if there is a deviation, the patient has grade I disease.
APTTV is above normal - what does it mean?
Causes leading to lengthening above the norm of activated partial thromboplastin time (APTT):
- Hemophilia A and B;
- Von Willebrand's disease;
- Congenital deficiency of precalicrein and cinnamon;
- Introduction of heparin or streptokinase;
- The condition after a large blood transfusion;
- Presence of lupus anticoagulant in the blood;
- Antiphospholipid syndrome;
- Chronic glomerulonephritis;
- Systemic lupus erythematosus;
- Reception of anticoagulants (Warfarin, Sinkumarin, etc.);
- Vitamin K deficiency;
- Low fibrinogen in the blood;
- Diseases of the liver;
- II and III phases of DIC syndrome;
- Deficiency of coagulation factors (II, V, VII, VIII, IX, X, XI, XII);
- Diseases of connective tissue.
As a rule, high results of APTT analysis indicate an increased risk of bleeding due to congenital or acquired deficiency of one or more coagulation factors.
APTTV is below normal - what does it mean?
Shortening of the APTT below the norm indicates the predominance of hypercoagulability and can be caused by the following reasons:
- Activation of the internal coagulation mechanism in thrombosis, thromboembolism. This may be due to factor V resistance to activated protein C, elevated levels of factor VIII, or activated clotting factors.
- With DIC-syndrome (hypercoagulation phase).
- Possible with a normal pregnancy.
Decrease in APTT indicates a tendency to thromboembolism.
What affects the results of the analysis
How does the decoding happen? What specifically affects the result of this analysis?
- A blood test contaminated with heparin.
- A sufficiently high hematocrit is able to extend the APTTV.
- The amount of blood that was taken for this analysis. The required ratio of blood taken and anticoagulant in the existing test tube is 9: 1.
- Folding of blood, when it leads to the consumption of all possible clotting factors, and also significantly changes the tolerance of APTT.
- A lot of factors are also influenced by fatty foods, smoking, the menstrual cycle and the presence of pregnancy in women. These factors can lead to falsely decreased APTT values.
The APTT value is very important for establishing an accurate picture of the patient's condition, especially during pregnancy. The results of the analysis allow not only to evaluate the work of the coagulation system, but also to reveal the presence of certain diseases. And the sooner a deviation of APTT from normal is detected, the easier and faster it is to cope with the disease.
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