Lupus Anticoagulant
Understanding Lupus Anticoagulant
What is Lupus Anticoagulant?
Lupus Anticoagulants (LA) are a type of antiphospholipid antibodies which attack the body's own immune system and healthy cells. They target phospholipids of the cell membrane and are known to cause antiphosholipid syndrome (APS) leading to frequent and abnormal blood clots. This can lead to formation of clots in multiple body parts including arms, legs, heart, lungs, stomach and kidney. Various complications such as cardiovascular diseases, stroke, kidney failure and lung damage can arise as a result of APS depending upon the organ affected by the blood clot.
LA test is recommended if a person suffers from frequent blood clotting or multiple miscarriages.
Early diagnosis is crucial to prevent the severity of APS.
A false positive result may be observed in case of a patient receiving blood thinners in treatment.
What is Lupus Anticoagulant used for?
The Lupus Anticoagulant Test is performed:
· To determine the cause of formation of abnormal blood clots inside blood vessels
· To help determine the cause of repeated miscarriages
· As a part of panel of tests performed to evaluate antiphospholipid syndrome
Interpreting Lupus Anticoagulant results
Interpretations
Normal levels:
PTT: 28.60 to 41.10 seconds
PTT-LA: 31.40 to 43.40 seconds
DRVVT: No LA present
Lupus Anticoagulant Tests are performed sequentially and results may be interpreted as follows:
|
Steps |
Tests |
Results |
Possible Interpretation |
|
Step 1 |
PTT-LA and/or DRVVT |
Normal |
No further testing required. Repeat testing if inhibitor suspected strongly. |
|
Prolonged |
Inhibitor may be present. To Step 2 |
||
|
Step 2 |
Mixing Study: Equal parts patient plasma and normal pooled plasma followed by PTT-LA and DRVVT |
Normal |
Abnormal Step 1 result due to coagulation factor deficiency. |
|
Prolonged |
Lupus anticoagulant may be present. To Step 3 |
||
|
Step 3 |
Confirmation (Correction or Neutralization test): Excess phospholipids added to patient plasma followed by PTT-LA or DRVVT. A ratio is calculated by dividing Step 3 result into Step 1 result. |
Positive (high ratio) |
Lupus anticoagulant present |
|
Negative (low ratio) |
Specific inhibitor other than lupus anticoagulant present. |
Based on recommendations of the International Society of Thrombosis and Hemostasis (ISTH) presence of LA is confirmed if four specific criteria are met:
· Prolonged result in at least one of PTT-LA or DRVVT tests
· Prolonged result in mixing study
· Reduction of clotting time occurs upon addition of excess phospholipids
· Ruling out other specific inhibitors of coagulation factors like factor VIII
Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Lupus Anticoagulant
Frequently Asked Questions about Lupus Anticoagulant
Q. Is there any preparation required before the test?
Q. Is there any risk associated with this test?
Q. What additional tests can be prescribed by your doctor in case of abnormal lupus anticoagulant test result?
Q. When can false results appear in Lupus Anticoagulant Test?
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