TPMT Genotyping Test: Booking, Price, and Results
About TPMT Genotyping Test: Booking, Price, and Results
| Field | Value |
|---|---|
| Also Known As | TPMT gene test, Thiopurine S-methyltransferase genotyping, TPMT pharmacogenetic test |
| Sample Type | Peripheral blood (EDTA tube) |
| Fasting Required | No fasting required |
| Report Time | 15 days |
| Recommended For | All individuals being considered for thiopurine drug therapy, regardless of age or gender |
| Price | Starting at ₹5,700 |
What is a TPMT Genotyping Test?
The TPMT genotyping test analyses your DNA to identify inherited variants in the TPMT gene. This gene controls how your body processes a group of medicines called thiopurines, which are used to treat certain cancers, autoimmune conditions, and inflammatory diseases. A small blood sample is collected from a vein in your arm. The test is also known as the TPMT gene test or the Thiopurine S-methyltransferase genotyping test.
What Does a TPMT Genotyping Test Measure?
The TPMT genotyping test procedure examines specific variants in the TPMT gene to predict how well your body will break down thiopurine drugs. The table below outlines what the test looks for.
| Component | What It Tells You |
|---|---|
| TPMT*1 (wild-type allele) | The normal gene variant associated with full enzyme activity |
| TPMT*2 variant | A known inactivating gene change that reduces enzyme function |
| TPMT*3A variant | The most common inactivating variant in European populations |
| TPMT*3C variant | A common inactivating variant across Asian populations |
| Predicted metaboliser status | Whether you are a normal, intermediate, or poor metaboliser of thiopurine drugs |
Why is a TPMT Genotyping Test Done?
This test is ordered before starting thiopurine therapy or when a patient has already shown unexpected side effects. Understanding your TPMT gene status helps doctors prescribe the right dose for you safely.
Common Symptoms That May Require This Test
This test is not triggered by symptoms in the traditional sense. It is requested based on clinical circumstances. The following situations commonly prompt a doctor to order it.
- About to start a thiopurine drug such as azathioprine, mercaptopurine, or thioguanine
- Unusual drop in white blood cell count (a sign of bone marrow suppression) after starting thiopurine therapy
- Persistent fatigue or signs of infection while on thiopurine treatment
- Recurrent episodes of low blood counts without a clear cause
- Diagnosis of acute lymphoblastic leukaemia (a blood cancer) in children or adults
- Diagnosis of an autoimmune condition, such as inflammatory bowel disease or rheumatoid arthritis, requiring thiopurine treatment
Conditions This Test Can Help Detect or Guide Treatment For
Several conditions are managed with thiopurine drugs, making the TPMT genotyping test relevant in each case.
- Acute lymphoblastic leukaemia (the most common cancer in children)
- Inflammatory bowel disease, including Crohn's disease
- Rheumatoid arthritis and other autoimmune conditions
- Organ transplant (where immunosuppression is required)
- Multiple sclerosis
How to Prepare and What to Expect
No special preparation is needed for this test. The steps below will help you know what to expect on the day.
Do You Need to Fast?
No. Fasting is not required before the TPMT genotyping test. You can eat and drink as normal before giving your sample.
Practical Tips Before Your Test
Keep the following points in mind before attending your appointment.
- Bring a detailed clinical history, including your symptoms, previous test results, and family history, as this is required for the test
- Tell your doctor about all medicines you currently take, as some drugs can affect TPMT enzyme activity
- Inform your doctor if you have had a blood transfusion in the past 60 days, as this may affect test accuracy
- Tell your doctor if you have previously received a bone marrow (haematopoietic stem cell) transplant from another person, as this can interfere with the result
- Wear a short-sleeved or loose-sleeved top for easy access to your arm during blood collection
Step-by-Step Procedure
Here is what happens during your sample collection appointment.
- A trained phlebotomist cleans the skin on your inner elbow with an antiseptic wipe.
- A fine needle is used to draw a small blood sample (2 ml) from a vein in your arm.
- The blood is collected into a lavender-topped EDTA tube to preserve the DNA.
- The tube is labelled with your details and stored at 2 to 8 degrees Celsius for transport.
- The sample is sent to the laboratory, where DNA is extracted from your blood cells.
- The laboratory analyses the DNA using Sanger sequencing to identify any TPMT gene variants present.
Factors That Can Affect Accuracy
The following factors may affect the reliability of your result.
- A blood transfusion received within the past 60 days may mask a TPMT deficiency
- A previous allogeneic bone marrow transplant (from another person) can introduce donor DNA and alter the result
- Improper sample storage or transport outside the required temperature range
- Individual and ethnic variation in TPMT gene expression, even among people carrying the same gene variants
Understanding Your TPMT Genotyping Test Results
Your results report the specific TPMT gene variants detected and translate them into a predicted metaboliser category. A doctor familiar with your medical history should always review these findings with you.
| Genotype | Predicted Status | What it Means |
|---|---|---|
| TPMT *1/*1 (both alleles normal) | Normal metaboliser | Approximately 86 to 97% of people fall here; standard thiopurine doses are generally well tolerated |
| One normal allele plus one variant allele | Intermediate metaboliser | Approximately 3 to 14% of people; reduced enzyme activity may require a lower thiopurine dose |
| Both alleles carry variants | Poor or deficient metaboliser | Affects roughly 1 in 178 to 1 in 3,736 people; the highest risk of severe bone marrow suppression at standard doses |
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 influence how results are interpreted.
- A recent blood transfusion can temporarily mask a complete TPMT deficiency because the transfused red blood cells carry the donor's gene activity rather than yours. Doctors usually wait until the donor cells have cleared (typically around six weeks after transfusion) before re-testing if needed.
- For South Asian and East Asian patients, NUDT15 gene variants are considerably more common than TPMT variants. Research shows about 3.5% of Indians carry TPMT variants, compared to 19.4% who carry NUDT15 variants. Combined testing for both genes is often recommended for these populations.
How to Maintain Healthy Levels
Because this is a genetic test, the results reflect inherited traits that cannot be changed by diet or lifestyle. The following steps help you stay safe once you know your status.
- Always tell every healthcare provider about your TPMT status before starting any new medication, particularly immunosuppressants
- If you are prescribed a thiopurine drug, attend all scheduled blood count monitoring appointments, as regular complete blood count (CBC) checks remain important regardless of your genetic result
- Carry a record of your TPMT genotype result so it is available to doctors in any clinical setting
Lupin Diagnostics TPMT Genotyping Test Price and Home Collection
The TPMT genotyping test cost at Lupin Diagnostics starts at ₹5,700, and home sample collection is available across cities in India.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 5700 |
| CHENNAI | 5700 |
| HYDERABAD | 5700 |
| KOLKATA | 5700 |
| NAVI MUMBAI | 5700 |
| PUNE | 5700 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
Follow these steps to book your TPMT genotyping test online.
- 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 the stipulated turnaround time.
Home Collection
Lupin Diagnostics offers TPMT genotyping test home collection across multiple cities, so you can give your blood sample from the comfort of your home. 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
The TPMT genotyping test identifies inherited variants in the TPMT gene to predict how your body will process thiopurine drugs. Doctors use this information to decide the right dose before starting treatment, reducing the risk of serious side effects such as bone marrow suppression.
This test is recommended for anyone about to start a thiopurine drug such as azathioprine, mercaptopurine, or thioguanine. It is also useful for patients already on these medicines who are experiencing unexpected drops in blood cell counts or other adverse reactions. Conditions such as leukaemia, inflammatory bowel disease, rheumatoid arthritis, and organ transplant all commonly involve thiopurine therapy.
No fasting is needed. You can eat and drink normally before the test. The only preparation required is to bring a clinical history and to inform your doctor about recent blood transfusions or any bone marrow transplant.
At Lupin Diagnostics, the report is delivered within 15 days of sample collection. This turnaround reflects the detailed Sanger sequencing method used to analyse your DNA.
A poor metaboliser result means both copies of your TPMT gene carry inactivating variants. At standard doses, thiopurine drugs pose a very high risk of severe bone marrow suppression for people in this category. Your doctor will discuss whether a greatly reduced dose or a different medicine is more appropriate for you.
Yes. Your genetic makeup does not change over time, so the test only needs to be done once. However, patients taking thiopurine drugs still require regular complete blood count monitoring, because genetic status alone does not replace ongoing clinical oversight.
Yes. If you have had a blood transfusion in the past 60 days, donor DNA may be present in your sample, and the result may not accurately reflect your own genotype. Let your doctor know about any recent transfusion so they can decide whether to delay testing until the donor cells have cleared.
TPMT Genotyping Test: Booking, Price, and Results
