Antithrombin III Activity Test: Booking, Price, and Results
About Antithrombin III Activity Test
| Field | Value |
|---|---|
| Also Known As | AT III, AT 3, Functional Antithrombin III test, Antithrombin Activity, DVT - AT III test |
| Sample Type | Venous blood (citrated plasma) |
| Fasting Required | No, typically no preparation needed |
| Report Time | 8 to 12 working days |
| Recommended For | Adults of all ages, males and females |
| Price | Starting at ₹2,500 |
What Is an Antithrombin III Activity Test?
The Antithrombin III Activity Test measures the level and working ability of Antithrombin III (AT III), a protein in your blood that naturally prevents harmful clot formation. Your doctor may order this AT III Activity Test if you have unexplained blood clots or a suspected clotting disorder. Also called the Functional Antithrombin III Test or AT3 Activity Test, it uses a small blood sample drawn from a vein.
What Does an Antithrombin III Activity Test Measure?
The Antithrombin III Assay evaluates how well your antithrombin protein is functioning. Antithrombin III works by inhibiting key clotting enzymes, particularly thrombin and factors Xa and IXa, helping keep your blood's clotting process in balance.
The table below shows the single parameter this test reports:
| Parameter | What It Tells You |
|---|---|
| Antithrombin III Activity | Whether the antithrombin protein in your blood is present at sufficient levels and working as it should to regulate clot formation |
Why Is an Antithrombin III Activity Test Done?
This test is ordered when a doctor needs to assess your blood's natural ability to control clotting. The following sections explain the common reasons it may be requested.
Common Symptoms That May Require This Test
- Unexplained blood clots in the legs or arms
- Leg swelling, redness, or pain (possible signs of deep vein thrombosis)
- Chest pain or sudden shortness of breath
- Recurrent miscarriages without a clear cause
- Heparin treatment not producing the expected anticoagulant effect
Conditions This Test Can Help Detect
An AT III Activity Test can help identify a range of clotting-related conditions, including:
- Hereditary antithrombin deficiency, an inherited disorder that raises the risk of abnormal clotting
- Deep vein thrombosis (blood clot in a deep vein) and pulmonary embolism (clot in the lungs)
- Phlebitis and thrombophlebitis (vein inflammation with or without clot formation)
- Liver disease such as cirrhosis or liver failure
- Nephrotic syndrome, a kidney condition that causes protein loss in urine
- Disseminated intravascular coagulation (DIC), a condition involving widespread abnormal clotting and bleeding
- Advanced cancer and certain gut conditions causing protein loss
Antithrombin III Activity Test for Chronic Disease Monitoring
For patients already diagnosed with hereditary or acquired antithrombin deficiency, this test is used to monitor the management of their condition over time. It is also used to monitor response to antithrombin concentrate therapy, which replaces the deficient protein. Repeat testing helps doctors adjust treatment plans as needed.
How to Prepare and What to Expect
Preparation for this test is minimal, but a few steps will help ensure accurate results.
Do You Need to Fast?
No fasting is required before the Antithrombin Activity Test. You can eat and drink normally before your appointment. However, if your doctor has ordered additional tests alongside this one, some of those may have their own preparation requirements, so confirm with your doctor.
Practical Tips Before Your Test
- Tell your doctor about all medications you are taking, especially blood thinners such as warfarin, ibuprofen, heparin, or newer anticoagulants like rivaroxaban or apixaban, as these can affect results
- Avoid getting this test done if you have received heparin therapy within the last 10 days, or within a few days of surgery or a clotting event, as levels may be temporarily altered
- Wear a short-sleeved top for easy access to your arm during the blood draw
- Stay well hydrated on the day of your test
Step-by-Step Procedure
- You will be asked to sit comfortably with your arm resting on a support. A band (tourniquet) is tied around your upper arm to make the vein easier to locate.
- The skin over the chosen vein is cleaned with an alcohol-based antiseptic. A sterile, single-use needle is gently inserted, and the tourniquet is released.
- A small amount of blood is collected into a specially labelled blue-top tube containing sodium citrate, which keeps the sample stable.
- The tube must be filled to the correct level, as the correct ratio of blood to citrate (9 parts blood to 1 part citrate) is critical for accurate results. The tube is gently inverted a few times to mix.
- The needle is removed, and light pressure is applied to the puncture site. The sample is labelled and sealed.
- The sample is processed to extract plasma and then sent to the laboratory for chromogenic assay.
Factors That Can Affect Accuracy
- Recent heparin use (within 10 days) may cause falsely low readings
- Medications such as warfarin may raise AT III levels, while direct factor Xa inhibitors (e.g., rivaroxaban, apixaban) may falsely elevate readings
- Recent surgery or a thrombotic event can temporarily reduce levels
- Sample quality issues such as an underfilled or overfilled tube, haemolysis (breakdown of red blood cells), lipaemia (fatty blood), or jaundice can affect the result
- Improper storage or handling of the sample after collection
Understanding Your Antithrombin III Activity Test Results
Results from the Antithrombin III blood Test should always be reviewed with your doctor, who will consider your full medical history and current medications before drawing any conclusions.
| Parameter | Age Group | Normal Range |
|---|---|---|
| Antithrombin III Activity | Newborns | 60 to 90% |
| Antithrombin III Activity | Children and Adults | 80 to 120% |
Note: Full-term newborns typically have lower levels that reach the adult range by around 90 days of age. Premature infants (born between 30 and 36 weeks) may take up to 180 days to reach normal values.
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain situations can affect how results should be read:
- Pregnancy: AT III levels can fall by up to 30% during pregnancy. Levels drop further immediately after childbirth. If you are pregnant, inform your doctor so that results are interpreted in the correct context.
- Oestrogen-containing medications: Oral contraceptives containing oestrogen may lower antithrombin levels, producing an acquired deficiency unrelated to genetics.
- Heparin resistance: Patients with antithrombin deficiency may require higher-than-usual heparin doses to achieve effective anticoagulation, which can itself be a sign prompting this test.
How to Maintain Healthy Levels
The following general wellness habits support overall circulatory health:
- Maintain a healthy weight and engage in regular physical activity to reduce clotting risk
- Stay well hydrated, particularly during long journeys or periods of reduced movement
- Discuss any medications or supplements you take with your doctor, especially those known to affect blood clotting
Lupin Diagnostics Antithrombin III Activity Test Price and Home Collection
The Antithrombin III Activity Test price at Lupin Diagnostics starts at approximately ₹2,500, with home sample collection available across cities.
| City | Approximate Price (₹) |
|---|---|
| Delhi | ₹3,400 |
| Mumbai | ₹3,400 |
| Bengaluru | ₹3,400 |
| Hyderabad | ₹3,400 |
| Chennai | ₹3,400 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website or app.
- Choose your city and preferred time slot.
- Opt for home sample collection by a certified phlebotomist, or visit your nearest Lupin Diagnostics centre.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Home Collection
Lupin Diagnostics offers home sample collection for the Antithrombin III Activity test near me across multiple cities in India. All samples are processed in NABL-accredited laboratories by trained staff. Your digital report is delivered securely via email or WhatsApp once ready.
Frequently Asked Questions
The Antithrombin III Activity test checks whether your blood contains sufficient antithrombin protein and whether it is functioning correctly. Doctors use it to investigate unexplained blood clots, diagnose hereditary or acquired antithrombin deficiency, and assess clotting disorders. It is also used to monitor treatment in patients with known deficiency.
No fasting is required. You can eat and drink as normal before your appointment. It is still a good idea to inform your doctor about any medications you are taking, as some can affect the test result.
Avoid this test if you have been on heparin therapy within the past 10 days, or shortly after surgery or a clotting episode, as AT III levels may be temporarily reduced in these situations and could lead to a misleading result. Your doctor will advise you on the best time to test.
The functional Antithrombin III test (activity assay) checks whether the protein is working properly. It is the standard first-line test. If the activity result is low, an antigen assay is then done to determine whether the body is producing too little antithrombin or producing a version that does not function correctly.
Low levels can result from hereditary deficiency, liver disease (such as cirrhosis or liver failure), nephrotic syndrome, disseminated intravascular coagulation, advanced cancer, and certain gut conditions that cause protein loss. Prolonged heparin therapy and some other medications can also reduce levels.
Yes. Antithrombin levels can fall significantly during pregnancy and drop further just after delivery. If you are pregnant or have recently given birth, let your doctor know before testing so that results are interpreted appropriately.
Results for the AT III Activity test are typically available within 8 to 12 working days from the date of sample collection. You will receive your report digitally through email or WhatsApp.
Antithrombin III Activity Test: Booking, Price, and Results
