Also called: AT test, AT3, Antithrombin III test
Report
{context.blood_test.parameters} Parameters
What it checks
Report delivery
Test for
Age group
Commonly advised for
The Anti-Thrombin III test measures the level of antithrombin, a natural protein that helps regulate blood clotting by preventing excessive clot formation. Deficiency of antithrombin increases the risk of abnormal blood clots in veins and arteries.
This test is crucial in evaluating inherited or acquired clotting disorders, especially in patients with unexplained or recurrent thrombosis.
You may be advised this test to:
Evaluate recurrent or unexplained blood clots
Investigate thrombosis occurring at a young age
Assess pregnancy-related clotting complications
Screen for inherited clotting disorders
Evaluate family history of thrombosis
Antithrombin is a natural anticoagulant protein produced by the liver. It works by inactivating several clotting factors, preventing excessive clot formation. When antithrombin levels are low, the balance shifts toward clot formation, significantly increasing thrombosis risk. This test helps identify both inherited deficiencies (present from birth) and acquired deficiencies (developing due to other conditions).
Recurrent deep vein thrombosis (DVT)
Pulmonary embolism
Blood clots at unusual sites
Thrombosis at a young age (under 50)
Pregnancy-related clotting events
Family history of clotting disorders
Unexplained clot formation
Early detection of antithrombin deficiency helps prevent life-threatening clot formation and allows timely initiation of anticoagulant therapy. It also helps guide treatment decisions and family screening.
Inform your doctor about all medications, especially anticoagulants
Testing is ideally done when not on blood thinners, as they can affect results
No fasting is typically required
Discuss timing with your doctor if you're pregnant or recently had surgery
A blood sample is drawn from a vein in your arm and sent to the laboratory for analysis using specialized immunoassay or functional activity testing methods.
Results are typically available within a few days. If levels are low, your doctor may recommend repeat testing to confirm the diagnosis and rule out temporary causes.
Immediately if you experience symptoms of blood clots such as leg pain and swelling, chest pain, shortness of breath, or if your test results show low antithrombin levels.
Minimal risk related to blood draw only, including slight bruising or discomfort at the puncture site.
Stay active and avoid prolonged immobility
Maintain adequate hydration
Follow prescribed anticoagulant therapy if recommended
Inform healthcare providers about your condition before surgery
Wear compression stockings during long travel if advised
Avoid smoking, which increases clot risk
The test measures the concentration and functional activity of antithrombin III, a key anticoagulant protein that regulates blood clot formation.
Normal levels (80–120%): Antithrombin deficiency unlikely
Low levels (<80%): Increased risk of abnormal blood clots; may indicate inherited or acquired deficiency
Borderline levels: May require repeat testing for confirmation
Seek specialist care (hematologist) for further evaluation, confirmatory testing, family screening, and discussion of long-term anticoagulation therapy if needed.
Current use of anticoagulants (heparin, warfarin)
Acute thrombosis or recent clot formation
Liver disease
Pregnancy
Recent surgery or trauma
Certain medications
Timing of sample collection
Is antithrombin deficiency common?
No, antithrombin deficiency is rare, occurring in approximately 1 in 2,000 to 5,000 people, though it accounts for a significant proportion of inherited clotting disorders in younger patients with unexplained thrombosis.
Is it inherited?
Yes, antithrombin deficiency is often inherited in an autosomal dominant pattern, meaning a child has a 50% chance of inheriting the condition if one parent carries the deficiency; however, acquired deficiency can also occur.
Can pregnancy affect levels?
Yes, pregnancy can lower antithrombin levels temporarily due to increased consumption, hemodilution, and hormonal changes, which increases clotting risk; testing may need careful interpretation during pregnancy and postpartum periods.
Is treatment lifelong?
Sometimes, treatment duration depends on whether the deficiency is inherited or acquired, and whether clots have occurred; those with inherited deficiency and recurrent clots typically require lifelong anticoagulation therapy.
Is repeat testing required?
Yes, repeat testing is usually required to confirm the diagnosis, especially if initial levels are borderline or if testing was done during acute illness, anticoagulant use, or pregnancy when results may be temporarily affected.
Antithrombin III is a natural protein that stops your blood from clotting too much. This test is advised if:
Tapadia Diagnostic Centre in Secunderabad offers NABL-accredited Antithrombin III test from a Blood sample(s). AT test, AT3, Antithrombin III test is also prescribed for Chest pain, leg swelling, breathing trouble. Established in 1989, this doctor-led diagnostic centre ensures high accuracy. Home sample collection and walk-in facility available at our Secunderabad center. Pay at the centre with no advance payment. Book online or visit us.
Sree Ranganatha Swamy Devasthanam, Yapral, H.No. 5-3-1, Bhagat Singh Nagar, Yapral
Services: Lab, ECG
Branch Incharge: Mr. Praveen Gupta : 9848056578
59/1/2(6-1R-002), Karkana,Secunderabad-09
Services: Lab, X Ray, ECG
Phone No: 9281063662
Branch Incharge: Mr. ASHOK : 9246846874
6-1-103, Ground Floor, Padma raonagar, Secunderabad.
Services: Lab, X Ray, ECG, U/S Scan
Phone No: 9390110059
Branch Incharge: Mr. Suman- 8179607955
Antithrombin III in Secunderabad
Rated 4.6 on Google
From 6,477 patient reviews across our Hyderabad centres.
Every report, kept for you
Past reports stay in your account and can be downloaded again.
NABL accredited
Every result reviewed by a qualified pathologist before it reaches you.
Four decades of practice
A family-run diagnostic centre, trusted by doctors and households since 1989


Antithrombin III in Vijayawada
Antithrombin III in Visakhapatnam
Antithrombin III in Ahmedabad
Antithrombin III in Bengaluru
Antithrombin III in Mumbai
Antithrombin III in Secunderabad
Antithrombin III in Karimnagar
Antithrombin III in Hyderabad
Antithrombin III in Warangal
Antithrombin III in Aurangabad
HIV 1 & 2 Antibodies, Serum-Elisa Method in Secunderabad
Dengue IgG, IgM Antibodies + NS1 Antigen-Rapid, Serum in Secunderabad
Lipoprotein A (Lp A), Serum in Secunderabad
Erythrocyte Sedimentation Rate (ESR) in Secunderabad
Thyroxine Total (T4), Serum in Secunderabad
Triiodothyronine Total (T3), Serum in Secunderabad
CA 19.9 (Pancreatic Cancer Marker), Serum in Secunderabad
NIPT with Microdeletions in Secunderabad
NIPT Basic in Secunderabad
Complete Blood Picture (CBP) in Secunderabad
Serum Phosphorus Test in Secunderabad
TIBC in Secunderabad
Urology Profile in Secunderabad
Beta HCG Free, Serum (Pregnancy Test) in Secunderabad
Viral Screening in Secunderabad
AFP Test in Secunderabad
Microalbuminuria test in Secunderabad
Diabetes Testing (FBS + PLBS) in Secunderabad
Antithrombin III in Secunderabad
D-dimer test in Secunderabad
Creatine Kinase (CK) Test in Secunderabad
AST Test in Secunderabad
Cardiac Markers in Secunderabad
Pap Smear - LBC in Secunderabad
DVT Profile in Secunderabad
Bleeding Time and Clotting Time (BT & CT) in Secunderabad
Estradiol Test in Secunderabad
hs-CRP Test in Secunderabad
Alkaline Phosphatase (ALP) Test in Secunderabad
Fertility Profile in Secunderabad
Albumin blood test in Secunderabad
Troponin T in Secunderabad
Infertility Profile Extended in Secunderabad
Electrolyte Panel in Secunderabad
Anticardiolipin Antibodies (IgG) in Secunderabad
PSA Test in Secunderabad
FSH Test in Secunderabad
STD Panel in Secunderabad
PCOS Profile in Secunderabad
Serum Iron Test in Secunderabad
Cardiac Profile-III in Secunderabad
Plasma Fibrinogen Test in Secunderabad
HBsAg Test in Secunderabad
Cardiac Biomarker Test in Secunderabad
Herpes Simplex Virus (HSV) Types 1 and 2 Antibody Test in Secunderabad
Antenatal Profile in Secunderabad
Activated Partial Thromboplastin Time in Secunderabad
Lipid Panel in Secunderabad
Fine Needle Aspiration Cytology in Secunderabad
CRP test in Secunderabad
Joint Pain / SLE / Collagen Profile-I in Secunderabad
PAPP-A Test in Secunderabad
Insulin Test in Secunderabad
Triple Screen Test in Secunderabad
Anti-HCV Test in Secunderabad
Basic Metabolic Panel (BMP) in Secunderabad
Very low-density lipoprotein (VLDL) test in Secunderabad
Free Testosterone in Secunderabad
Triglycerides Test in Secunderabad
Quad Screen in Secunderabad
Folic Acid in Secunderabad
Urinalysis in Secunderabad
CEA Test in Secunderabad
Ferritin Test in Secunderabad
Transferrin Saturation% in Secunderabad
Protein C Antigen in Secunderabad
Alpha Feto Protein (AFP) - Fluid in Secunderabad
CPK (MB) Test in Secunderabad
Lupus Anticoagulant Testing in Secunderabad
Reticulocyte Count in Secunderabad
Infertility Profile-Basic in Secunderabad
Beta hCG Test in Secunderabad
DIABETIC PROFILE in Secunderabad
LH Test in Secunderabad
Anti-Müllerian Hormone (AMH) Test in Secunderabad
Bile Salts and Bile Pigments, Urine in Secunderabad
HbA1c in Secunderabad
Vitamin D (1,25-Dihydroxyvitamin D) in Secunderabad
Liver Function Test (LFT) in Secunderabad
Anemia Profile Basic in Secunderabad
Rheumatoid Factor in Secunderabad
Widal Test in Secunderabad
Bilirubin blood test in Secunderabad
Inhibin A, Tumor Marker, Serum in Secunderabad
Thyroid Function Tests in Secunderabad
eGFR in Secunderabad
Menopause Profile in Secunderabad
EXTENDED DIABETIC PROFILE in Secunderabad
LDH Test in Secunderabad
Total Cholesterol Test in Secunderabad
Random Blood Sugar Test in Secunderabad
Total Protein Test in Secunderabad
RPR test in Secunderabad
Anti-dsDNA Test in Secunderabad
HDL Cholesterol in Secunderabad
Blood Type Test in Secunderabad
ASO Titre in Secunderabad
Blood Urea(Serum) Test in Secunderabad
Postprandial Blood Sugar Test in Secunderabad
Back Pain Profile in Secunderabad
ANA test in Secunderabad
Serum Creatinine Test in Secunderabad
PT/INR Test in Secunderabad
Fasting Blood Sugar Test in Secunderabad
Extended Anemia Profile III Executive in Secunderabad
Kidney Function Test (Renal Profile) in Secunderabad
Serum Magnesium Test in Secunderabad
Well-woman exam in Secunderabad
LDL cholesterol test in Secunderabad
Prolactin Test in Secunderabad
Malaria Blood Smear in Secunderabad
Liver Function Test (+GGT) in Secunderabad
TPHA Test in Secunderabad
Hepatitis B Surface Antigen (HBsAg) Test in Secunderabad
Antenatal Profile 2 in Secunderabad
TSH Test in Secunderabad
Cardiac Catheterization in Secunderabad
Cardiolipin Antibody (IgM) in Secunderabad
Master Health Checkup in Secunderabad
Calcium Profile in Secunderabad
Coagulation Profile in Secunderabad
Uric Acid Test in Secunderabad
Vitamin D (25 - Hydroxy Vitamin D, Serum) in Secunderabad
Globulin Test in Secunderabad
Fever Profile Test in Secunderabad
Connective Tissue Disease Profile in Secunderabad
Calcium Blood Test in Secunderabad
IHC in Secunderabad
Estriol Unconjugated (E3) Test in Secunderabad
Blood Typing in Secunderabad
Vitamin B12 Test in Secunderabad
Serum Cortisol in Secunderabad
Double Marker Test in Secunderabad
Pap Smear, Conventional in Secunderabad
Protein S Activity in Secunderabad
Non-Invasive Prenatal Testing (NIPT) in Secunderabad
whole exome sequencing in Secunderabad
Newborn Screening (NBS) in Secunderabad
Renal Function Test (RFT) in Secunderabad