TDT by Flowcytometry Test: Booking, Price, and Results
About TDT by Flowcytometry Test: Booking, Price, and Results
| Field | Value |
|---|---|
| Also Known As | Terminal Deoxynucleotidyl Transferase by Flow Cytometry, TdT Flow Cytometry, TdT Immunophenotyping, TdT FCM |
| Sample Type | Whole blood in EDTA (lavender top) tube |
| Fasting Required | No |
| Report Time | 3 days |
| Recommended For | All ages; males and females when leukaemia or lymphoma is suspected |
| Price | Starting at ₹2,300 |
What Is a TDT by Flowcytometry Test?
The TDT by Flowcytometry test measures the presence of an enzyme called Terminal Deoxynucleotidyl Transferase (TdT) in blood or bone marrow cells. TdT is normally found only in immature, developing white blood cells and is not present in mature circulating blood cells. Doctors order this test when leukaemia or lymphoma is suspected, as it helps classify the type and stage of the cancer. The test is also known as TdT Flow Cytometry or TdT Immunophenotyping.
What Does a TDT by Flowcytometry Test Measure?
The TDT by Flowcytometry test procedure uses a technology called flow cytometry to detect and quantify the TdT enzyme in cells. Cells are labelled with fluorescent antibodies and passed through a laser-based instrument that analyses them one by one.
The key marker this test evaluates is:
| Parameter | What It Indicates |
|---|---|
| Terminal Deoxynucleotidyl Transferase (TdT) in peripheral blood | Whether immature lymphoid cells are present in circulating blood (normally negative) |
| TdT in bone marrow | The proportion of TdT-positive cells among bone marrow lymphocytes (1 to 2% is normal) |
TdT adds building blocks to DNA strands during the early development of T and B lymphocytes (two types of white blood cells). Its detection in large numbers of cells points to an abnormal accumulation of immature cells, which is a hallmark of certain blood cancers.
Why Is a TDT by Flowcytometry Test Done?
This test is a specialised diagnostic tool used primarily in blood cancer investigation and monitoring. A doctor may prescribe it for several reasons.
Common Symptoms That May Require This Test
The following symptoms may prompt a doctor to request this test:
- Persistent fatigue or unexplained tiredness
- Frequent infections or slow recovery from illnesses
- Unexplained fever or night sweats
- Easy bruising or unusual bleeding
- Bone or joint pain without a clear cause
- Swollen lymph nodes (lumps under the skin near the neck, armpits, or groin)
Conditions This Test Can Help Detect
This test helps identify a range of blood and lymph system cancers, including:
- Acute lymphoblastic leukaemia (ALL), a cancer of immature white blood cells
- Lymphoblastic lymphoma, a cancer of lymph tissue with similar cell characteristics
- Mixed lineage leukaemia, where the cancer cells show features of more than one cell type
- Acute myelogenous leukaemia (AML) in certain cases
- Chronic myeloid leukaemia in blast crisis, where the disease transforms into a more aggressive phase
TDT by Flowcytometry Test for Chronic Disease Monitoring
The TDT by Flowcytometry test plays an important role in monitoring minimal residual disease (MRD) in patients being treated for acute lymphoblastic leukaemia. MRD refers to the small number of cancer cells that may remain in the body after treatment. Tracking TdT-positive cells alongside markers such as CD10, CD19, and CD34 helps doctors assess how well the treatment is working and detect early signs of relapse.
How to Prepare and What to Expect
The test requires only a small amount of preparation. Here is what you need to know before your appointment.
Do You Need to Fast?
No fasting is required before this test. You can eat and drink normally on the day of your sample collection.
Practical Tips Before Your Test
Keep the following points in mind ahead of your appointment:
- Bring a detailed clinical history, including your symptoms, previous test results, and any relevant medical records, as this is required for the test.
- Inform the doctor or phlebotomist about all medications and supplements you are taking, as some can affect results.
- Stay well hydrated before your appointment.
- Wear a loose-sleeved top so the phlebotomist can access your arm easily.
- Discuss the timing of sample collection with your centre, as samples need to be processed promptly.
Step-by-Step Procedure
The sample collection for the TDT by Flowcytometry test procedure typically follows these steps:
- A trained phlebotomist cleans a vein on your inner arm with an antiseptic wipe.
- A needle is gently inserted, and approximately 5 mL of blood is collected into a lavender-top EDTA tube.
- The tube is inverted several times gently to mix the blood with the anticoagulant inside, ensuring proper preservation.
- The labelled sample is stored at refrigeration temperature (2 to 8°C) and dispatched to the laboratory promptly.
- In the laboratory, cells are stained with fluorescent antibodies specific to TdT and analysed on a flow cytometer.
- A haematopathologist (a specialist in blood cell diseases) interprets the results and prepares your report.
Note: If your doctor has also requested a bone marrow sample, that procedure will be carried out at a hospital and cannot be collected at home.
Factors That Can Affect Accuracy
Several factors may influence the reliability of your results:
- Certain medications or immune system conditions affecting blood cells
- Poor sample quality or delays in processing after collection
- Inadequate mixing of the blood sample with the anticoagulant
- Technical issues such as high background staining in the laboratory
Understanding Your TDT by Flowcytometry Test Results
Your doctor will review your results alongside your symptoms, medical history, and other test findings. The table below provides general reference values for context.
| Parameter | Normal Range |
|---|---|
| TdT in peripheral blood | Negative (not detected) |
| TdT in bone marrow | 1% to 2% of lymphocytes |
A result above the normal range, particularly a finding of more than 40% TdT-positive cells, may suggest acute lymphoblastic leukaemia or a related condition. A negative or low result in a patient under treatment may indicate a good response.
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
Bone marrow regeneration can complicate interpretation of this test. Normal immature B cells (called haematogones) also express TdT, and their numbers increase in children and in patients recovering from chemotherapy or stem cell transplantation. This can make it harder to distinguish normal cells from leukaemic cells, so specialist interpretation is essential.
How to Maintain Healthy Levels
These general wellness tips support overall blood and immune health:
- Eat a balanced diet that includes fruits, vegetables, and whole grains to support your immune system.
- Attend regular health check-ups, especially if you have a family history of blood cancers.
- Report persistent symptoms, such as fatigue, frequent infections, or unexplained bruising, to your doctor without delay.
Lupin Diagnostics TDT by Flowcytometry Test Price and Home Collection
The TDT by Flowcytometry test cost at Lupin Diagnostics starts at ₹2,300, and home collection is available for peripheral blood samples.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 2300 |
| CHENNAI | 2300 |
| HYDERABAD | 2300 |
| KOLKATA | 2300 |
| NAVI MUMBAI | 2300 |
| PUNE | 2300 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
You can book the TDT by Flowcytometry test online booking in a few simple steps:
- Select the test on the Lupin Diagnostics website.
- 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 3 days.
Home Collection
TDT by Flowcytometry test home collection is available for peripheral blood samples across cities served by Lupin Diagnostics. All samples are processed in NABL-accredited laboratories by experienced specialists. Your digital report is delivered securely via email or WhatsApp once ready.
Frequently Asked Questions
This test helps diagnose and classify blood cancers such as acute lymphoblastic leukaemia and lymphoblastic lymphoma. It detects TdT, an enzyme present in immature white blood cells, and helps doctors determine the type and developmental stage of abnormal cells.
No fasting is required. You can eat and drink as usual before your appointment. However, do inform the doctor about any medications or supplements you are taking, as these may influence results.
For the TDT by Flowcytometry test procedure, a blood sample is drawn from a vein in your arm and collected in a lavender-top EDTA tube. If your doctor also requests a bone marrow sample, that procedure must be performed at a hospital and is not available via home collection.
A positive result means TdT-positive cells were detected at levels above normal. This may suggest acute lymphoblastic leukaemia or a related condition, but it is not a stand-alone diagnosis. Your doctor will order additional tests and review your full clinical picture before drawing any conclusions.
An abnormal result should be discussed with a haematologist, a doctor who specialises in blood disorders. They will review the findings in the context of your symptoms and medical history and advise on any further steps needed.
Yes. In patients diagnosed with acute lymphoblastic leukaemia, this test is used to track minimal residual disease (MRD), which refers to small numbers of cancer cells that may remain after treatment. Repeat testing helps doctors assess treatment response and watch for early signs of relapse.
TDT by Flowcytometry Test: Booking, Price, and Results
