APTT (Activated Partial Thromboplastin Time) Test Purpose, Procedure, Result Interpretation and Your Test Result Meaning

APTT (Activated Partial Thromboplastin Time) is a laboratory test that measures the time it takes for blood plasma to clot through the intrinsic pathway of the coagulation cascade after activation. It is a more sensitive version of the Partial Thromboplastin Time (PTT) test.

Also Known as	PTT, APTT, Partial Thromboplastin Time, Activated Partial Thromboplastin Time,
Test Purpose	measures the number of seconds it takes for a clot to form in a sample
Test Preparations	No Need but Overnight Fasting Is Preferred
Test Components	APTT, PTT
Specimen	3 ML Whole Blood In 1 Blue Top (Sodium Citrate) Tube. Mix Thoroughly By Inversion.
Stability Room	2 hours
Stability Refrigerated	4 hours
Stability Frozen	2 weeks
Method	Photo-Optical Clot Detection
Download Report	Download Report

Definations:

PTT:

PTT, which stands for Partial Thromboplastin Time, is a laboratory test used to evaluate the intrinsic pathway of the coagulation cascade. It measures the time it takes for blood plasma to clot after the addition of a phospholipid-based reagent.

APTT:

APTT, which stands for Activated Partial Thromboplastin Time, is a laboratory test used to evaluate the intrinsic pathway of the coagulation cascade after activation with a specific activator. It measures the time it takes for blood plasma to clot after the addition of an activator, such as kaolin or ellagic acid.

Purpose of the test (Indications)

1. This is used for the diagnosis of bleeding disorders.
2. APTT may be used in the patient to check treatment who are taking Heparin or other blood-thinning medicines.
3. APTT measures the intrinsic system and common pathways.
4. APTT detects the functioning of factors XII, XI, X, IX, VII, V, II, and I (12, 11, 10, 9, 7, 2, 1).
5. For the diagnosis of Hemophilia and Christmas disease.

Why get Tested:

Your doctor might order this test to check for a bleeding disorder, such as hemophilia or von Willebrand disease. Symptoms of bleeding disorders include:

• Bleeding or bruising easily
• Blood clots that form when they shouldn’t
• Blood in your poop or urine
• Gums that bleed easily
• Heavy menstrual periods in women.
• nosebleeds
• Swelling or pain in the joints

When To Get Tested?

When you have unexplained bleeding, inappropriate blood clotting, or recurrent miscarriages; sometimes when you are on standard heparin anticoagulant therapy; sometimes before a scheduled surgery

Sample Required:

1. The blood is collected in an anticoagulant with a fixed ratio carefully.
   • Take 0.2 ml anticoagulant (ESR solution may be used) and 1.8 ml whole blood.
2. The APTT sample may be taken 30 to 60 min before the next dose of Heparin.

Precaution for sample

1. Plasma is stable for one hour at 4 °C and 28 days if frozen.
2. Sample handling is very critical. If the ratio of blood and anticoagulant is not correct, then the results are false and raised.

Normal Values:

Source 1

• Varies with the lab to lab.
• Normal control is always run with the patient sample.
• In general, is <35 seconds.
  • PTT: 60 to 70 seconds.
  • APTT: 30 to 40 seconds.
• If APTT is less than 50 seconds then the therapeutic goal is not achieved and the dose of Heparin may be increased.
  • When APTT is greater than 100 seconds is risky for the patient and there are chances for spontaneous bleeding.
  • Panic value Usually it is considered above 70 seconds.
• Heparin effect is immediate and short-lived as compared to warfarin.

Source 2

• APTT = 30 to 40 seconds
• PTT = 60 to 70 seconds
• Possible critical values
  • APTT = >70 seconds
  • PTT = > 100 seconds

Abnormal High Results Are Due To:

• All congenital deficiencies of Intrinsic system coagulation factors.
• Cirrhosis.
• Disseminated intravascular coagulopathy (DIC ).
• Factor XII deficiency.
• Hemophilia A and B.
• Hypofibrinogenemia.
• Malabsorption.
• Von Willebrand’s disease.
• Vit K deficiency.
• Fibrin breakdown products.
• Leukemia.
• Drugs.

Table of Differences Between PTT and APTT:

PTT (Partial Thromboplastin Time)	APTT (Activated Partial Thromboplastin Time)
Measures the time it takes for blood to clot through the intrinsic pathway of coagulation.	Measures the time it takes for blood to clot through the intrinsic pathway of coagulation after activation with a specific activator.
Involves the addition of a phospholipid-based reagent to initiate the coagulation process.	Involves the addition of an activator, such as kaolin or ellagic acid, to initiate the coagulation process.
Typically used to monitor heparin therapy, as heparin affects the intrinsic pathway.	Typically used to monitor heparin therapy, as heparin affects the intrinsic pathway.
Used to evaluate bleeding disorders, such as hemophilia or von Willebrand disease.	Used to evaluate bleeding disorders, such as hemophilia or von Willebrand disease.
Results are reported in seconds.	Results are reported in seconds.
Normal range varies depending on the laboratory and reagents used, typically around 25-35 seconds.	Normal range varies depending on the laboratory and reagents used, typically around 25-35 seconds.
Prolonged PTT may indicate a clotting factor deficiency or presence of an inhibitor.	Prolonged APTT may indicate a clotting factor deficiency or presence of an inhibitor.
May be influenced by various factors such as lupus anticoagulant or specific factor deficiencies.	May be influenced by various factors such as lupus anticoagulant or specific factor deficiencies.
Can be used to screen for a variety of clotting disorders.	Can be used to screen for a variety of clotting disorders.
Can be affected by sample handling and pre-analytical variables.	Can be affected by sample handling and pre-analytical variables.

Table of Similarities Between PTT and APTT:

PTT (Partial Thromboplastin Time)	APTT (Activated Partial Thromboplastin Time)
Both are laboratory tests used to assess the intrinsic pathway of the coagulation cascade.	Both are laboratory tests used to assess the intrinsic pathway of the coagulation cascade.
Both involve the measurement of the time it takes for blood to clot.	Both involve the measurement of the time it takes for blood to clot.
Both assess the functionality of factors involved in the intrinsic pathway, including clotting factors VIII, IX, XI, and XII.	Both assess the functionality of factors involved in the intrinsic pathway, including clotting factors VIII, IX, XI, and XII.
Both can be used to evaluate and monitor bleeding disorders, such as hemophilia or von Willebrand disease.	Both can be used to evaluate and monitor bleeding disorders, such as hemophilia or von Willebrand disease.
Both can be prolonged in the presence of clotting factor deficiencies or inhibitors.	Both can be prolonged in the presence of clotting factor deficiencies or inhibitors.
Both are typically reported in seconds.	Both are typically reported in seconds.
Normal range can vary depending on the laboratory and reagents used, typically around 25-35 seconds.	Normal range can vary depending on the laboratory and reagents used, typically around 25-35 seconds.
Both may be influenced by factors such as lupus anticoagulant or specific factor deficiencies.	Both may be influenced by factors such as lupus anticoagulant or specific factor deficiencies.
Both can be used as screening tests for a variety of clotting disorders.	Both can be used as screening tests for a variety of clotting disorders.
Both can be affected by sample handling and pre-analytical variables.	Both can be affected by sample handling and pre-analytical variables.

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Possible References Used

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