Activated partial thromboplastin time (APTT) measurement assay

Summary

The activated partial thromboplastin time assay test can be used to: screen endogenous coagulation systems more sensitively.

Operation method

Activated partial thromboplastin time (APTT) measurement assay

Principle

To plasma add partial coagulation activity solution, under the participation of Ca2 + fibrinogen transformed into insoluble fibrin, determination of the time required for coagulation, that is, the plasma activated partial thromboplastin time to be measured, (APTT).APTT assay is a quantitative test of endogenous pathway coagulation factors, can detect other plasma coagulation factors except factor VII, especially for factor VIII, IX, Ⅻ, and the pre-peptide release enzymes, while the APTT assay can be used for heparin therapy monitoring.

Materials and Instruments

Blood Specimens
Sodium citrate anticoagulant
Siliconized glass tubes Plastic tubes

Move

I. Materials and reagents:

Source and preservation of specimens:

Blood was collected intravenously and placed in a plastic or siliconized glass tube containing 1/10 volume of 0.109 mol/L sodium citrate anticoagulant (1 part of anticoagulant 10 parts of 9 parts of whole blood), and then gently inverted to mix well. 3,000 rpw (or 2500) centrifugation was carried out for 15 minutes, and the supernatant layer of the liquid was collected.

Experimental methods:

1. Take 0.lml of plasma to be tested (Dobie plasma), pre-warmed at 37℃, then add 0.1ml of pre-warmed APTT suspension at 37℃ and mix well, incubate at 37℃ for 5min.

2. Add 0.lml of pre-warmed 0.025M _CaCl2 solution at 37℃ and mix well, then start the stopwatch immediately to record the coagulation time.

Normal value: 23-35 seconds, more than 10 seconds above abnormal.

Caveat

1. Before the examination：

（1） The day before the blood draw, do not eat too greasy, high protein food, and avoid drinking a lot of alcohol. The alcohol content in the blood will directly affect the test results.(2) After eight o'clock in the evening of the day before the physical examination, you should start to fast for 12 hours so as not to affect the test results.(3) When drawing blood, you should relax to avoid the contraction of blood vessels caused by fear, which will increase the difficulty of blood collection.

2. After the test：

（1） After the blood is drawn, local pressure needs to be applied at the needle hole for 3-5 minutes to stop bleeding. Note: Do not rub, so as not to cause subcutaneous hematoma.(2) The time of pressure should be sufficient. The clotting time varies from person to person, and some people need a slightly longer time to clot. Therefore, if the pressure is stopped immediately when the skin surface does not seem to be bleeding, the blood may not be stopped completely, and the blood may seep into the subcutaneous area and cause bruising. Therefore, press for a longer period of time in order to completely stop the bleeding. If there is a tendency to bleed, the duration of pressure should be prolonged.(3) If there are symptoms of needle-sickness such as dizziness, blurred vision and fatigue after blood sampling, one should lie down immediately, drink a small amount of sugar water and wait until the symptoms are relieved before carrying out the physical examination.(4) If localized bruising occurs, use a warm towel to apply wet compress after 24 hours to promote absorption.

3、Unsuitable people: those who are blood-sick.

Common Problems

1, compared with the shortening of PT results, the chances of APTT shortening is much higher but a few because the activity of factor VIII or factor XII is particularly high, the existence of hypercoagulable state, the rest is mostly technical reasons. The rest are mostly due to technical reasons, such as incomplete removal of platelets when separating plasma, improper specimen collection, and so on.

2、Because of the high sensitivity of APTT to heparin, it is now widely used in the monitoring of anticoagulant therapy with ordinary heparin, but for the detection of low molecular heparin, APTT is not sensitive.

3、Simultaneous detection of APTT and PT is the main screening test for coagulation factor defects. APTT is prolonged in patients with obvious defects of factors VIII, IX, and XI, but it may be prolonged insignificantly or not in patients with mild or subclinical type (factor activity about 20%-40% of normal).

This experiment was obtained from Mudanjiang Medical College, Laboratory Guidance for Testing Specialties.

For more product details, please visit Aladdin Scientific website.

https://www.aladdinsci.com/