Chimerism by STR (Posttransplant) Test
About Chimerism by STR (Posttransplant) Test
| Field | Value |
|---|---|
| Also Known As | Chimerism Analysis Post-Transplant, Engraftment Analysis, Post-HSCT Chimerism Study, STR-PCR Chimerism Test, Donor Chimerism Testing |
| Sample Type | Peripheral blood (EDTA tube) |
| Fasting Required | No fasting required |
| Report Time | 15 days |
| Recommended For | All ages; patients who have undergone an allogeneic bone marrow or stem cell transplant |
| Price | Starting at ₹9,000 |
What is a Chimerism by STR (Posttransplant) Test?
The Chimerism by STR (posttransplant) test is a specialised molecular test performed on patients who have received a bone marrow or stem cell transplant from a donor. It measures the proportion of donor cells and recipient cells present in the blood after the transplant. The test uses short tandem repeats (STRs), which are small repeating DNA patterns unique to each person, as identity markers to tell the two cell populations apart. It is also known as the Chimerism Analysis Post-Transplant or Donor Chimerism Testing.
What Does a Chimerism by STR (Posttransplant) Test Measure?
This test analyses DNA from your blood sample to determine how much of your cell population comes from the donor and how much remains from you (the recipient). The two key outcomes measured are described below.
| Parameter | What It Means |
|---|---|
| Complete Donor Chimerism | 95% or more of the cells detected are from the donor, indicating successful engraftment |
| Mixed Chimerism | Less than 95% donor cells detected; both donor and recipient DNA are present in the sample |
| Split Chimerism | When different types of blood cells (for eg, myeloid cells and T cells) show varying ratios of donor and recipient origin |
The percentages of donor and recipient cells are calculated by comparing STR patterns in your post-transplant sample against pre-transplant baseline samples from both donor and recipient.
Why is a Chimerism by STR (Posttransplant) Test Done?
This test is an important part of post-transplant care. It is ordered at regular intervals to track how well the transplanted cells have settled into the body.
Common Symptoms That May Require This Test
Your transplant team may order this test in the following situations.
- Routine monitoring after an allogeneic stem cell or bone marrow transplant
- Declining or unexplained drop in blood cell counts
- Suspected graft rejection or graft failure
- Signs of possible disease relapse
- Unexplained anaemia, bleeding tendency, or recurrent infections
- Assessment of response to treatment, such as donor lymphocyte infusion
- Evaluation of engraftment status at scheduled post-transplant timepoints
Conditions This Test Can Help Detect
This STR chimerism test helps identify or confirm the following conditions.
- Successful engraftment, confirming donor cells have taken hold
- Impending graft rejection, by detecting a rising proportion of recipient cells
- Graft failure, attributed to either immune rejection or poor graft function
- Disease relapse in conditions such as leukaemia, lymphoma, aplastic anaemia, thalassaemia, and congenital immune diseases
Chimerism by STR (Posttransplant) Test for Chronic Disease Monitoring
Routine chimerism by STR testing is a standard part of long-term post-transplant care. Most transplant programmes schedule testing at day 30, day 90, day 180, and one year post-transplant, with additional tests as the clinical situation requires. Tracking chimerism over time allows the transplant team to identify early signs of relapse or graft loss, often before other symptoms appear.
How to Prepare and What to Expect
No special preparation is needed for this test. The steps below explain what happens on the day of sample collection.
Do You Need to Fast?
No fasting is required before this test. You may eat and drink normally before your appointment.
Practical Tips Before Your Test
A few simple steps will help ensure accurate results.
- Bring a detailed clinical history, including your transplant date, donor details, previous chimerism results, current medications, and any recent symptoms, as this is required for the test
- Inform your doctor about all medications you are currently taking, including immunosuppressants
- Ensure pre-transplant baseline samples from both donor and recipient have been collected and stored for comparison
- The blood sample must reach the laboratory within 72 hours of collection, so arrange prompt transport if booking home collection
- Wear a loose-sleeved top for easy access to the arm during the blood draw
Step-by-Step Procedure
Here is what happens during a Chimerism by STR test blood collection.
- A trained phlebotomist cleans the skin over a vein in your arm.
- A small needle is inserted to draw 2 ml of blood into a lavender-top EDTA tube.
- The sample is labelled with your details and stored at 2 to 8°C for refrigerated transport.
- The sample is dispatched promptly to the laboratory and must arrive within the required timeframe.
- In the lab, DNA is extracted from blood cells, and selected STR regions are amplified by polymerase chain reaction (PCR). This technique makes many copies of specific DNA segments.
- The lengths of the amplified DNA fragments are compared between the post-transplant sample and the pre-transplant baseline samples to calculate the percentage of donor and recipient cells.
Factors That Can Affect Accuracy
The following factors may influence the reliability of results.
- Blood transfusions received close to the date of sample collection
- Low white blood cell counts, which reduce the amount of DNA available
- Sample degradation if the specimen is not transported or stored correctly
- DNA contamination during collection or handling
- The method has a sensitivity limit of approximately 1% to 5%, meaning very small cell populations may not be detected
Understanding Your Chimerism by STR (Posttransplant) Test Results
Results from this test show the percentage of donor and recipient cells in your blood sample. Your transplant team will review these results together with your clinical history and other investigations. The table below provides general reference ranges.
| Parameter | Expected Range | Interpretation |
|---|---|---|
| Complete Donor Chimerism | 95% to 100% donor cells | Successful engraftment; donor cells are dominant |
| Mixed Chimerism | Less than 95% donor cells | Presence of both donor and recipient cells; requires clinical review |
| Abnormal (Autologous Recovery) | 100% recipient DNA | Indicates a failed graft or relapse of the original disease |
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 factors can affect how results are read.
A rising proportion of recipient cells (increasing mixed chimerism) may indicate graft rejection or possible disease relapse, and your transplant team will assess whether any intervention is needed. If a blood transfusion was given shortly before the sample was collected, this can temporarily affect DNA proportions and should be disclosed to your doctor when results are reviewed.
How to Maintain Healthy Levels
While the test results are determined by your transplant outcome, these general steps support your recovery.
- Attend all scheduled post-transplant monitoring appointments, so your team can track chimerism trends over time
- Report any new symptoms, such as fatigue, unusual bleeding, or signs of infection, to your transplant team without delay
- Follow your transplant team's guidance regarding immunosuppressant medications and any recommended lifestyle adjustments
Lupin Diagnostics Chimerism by STR (Posttransplant) Test Price and Home Collection
The Chimerism by STR (posttransplant) test is available at Lupin Diagnostics starting at ₹9,000, with home blood collection available across certain cities.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 9000 |
| CHENNAI | 9000 |
| HYDERABAD | 9000 |
| KOLKATA | 9000 |
| NAVI MUMBAI | 9000 |
| PUNE | 9000 |
Disclaimer: 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 Chimerism by STR 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
Home collection for the Chimerism by STR (posttransplant) test is available across cities through Lupin Diagnostics. All samples are processed in NABL-accredited laboratories by experienced professionals. Your digital report is delivered securely via email or WhatsApp once ready.
Frequently Asked Questions
The Chimerism by STR test tracks the proportion of donor and recipient cells in a patient's blood after a bone marrow or stem cell transplant. It uses DNA identity markers called short tandem repeats to distinguish between donor and recipient cells, helping the transplant team confirm whether the donated cells have successfully established themselves in the body.
Serial measurements of chimerism are essential for monitoring donor cell engraftment, detecting potential graft rejection, and identifying early signs of disease relapse. Your transplant team uses the results to make informed decisions about your ongoing care and any need for intervention.
Testing frequency depends on your condition, the type of transplant, and your doctor's recommendations. Most programmes schedule tests at day 30, day 90, day 180, and one year post-transplant. Your team may order additional tests if your results change or if new symptoms arise.
Mixed chimerism means that both donor and recipient cells are detected in your blood sample. Some mixed chimerism is common in the early weeks after transplant. However, persistent or increasing recipient cell proportions may require clinical review and possible treatment.
The test requires a standard blood draw, which involves a brief, mild discomfort similar to any routine blood test. Most people find it straightforward and fairly tolerable.
At Lupin Diagnostics, the report for this test is delivered within 15 days. The turnaround time reflects the detailed laboratory analysis involved in DNA extraction, PCR amplification, and fragment analysis.
Yes, home collection is available for the blood sample. It is important to ensure the sample is transported promptly and reaches the laboratory within the required timeframe to maintain sample quality and test accuracy.
Chimerism by STR (Posttransplant) Test
