Understanding Lab Tests for Organ Transplant Rejection
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Organ transplant rejection occurs when the immune system attacks a transplanted organ, recognizing it as foreign tissue. While rejection is primarily diagnosed through tissue biopsies and imaging studies, blood testing plays a crucial role in monitoring immunosuppressive medications that prevent rejection and assessing the body's response to transplant therapy.
Recommended Test
Sirolimus, LC/MS/MS
This test measures blood levels of sirolimus, an immunosuppressant medication used to prevent organ rejection after transplantation. Monitoring sirolimus levels is critical because levels that are too low may indicate inadequate immunosuppression, increasing the risk of organ rejection, while levels that are too high can lead to medication toxicity and serious side effects. Regular monitoring ensures optimal therapeutic dosing.
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The Role of Blood Testing in Transplant Care
Although there isn't a single blood test to directly diagnose organ rejection, laboratory monitoring is fundamental for successful transplant management. Blood tests help ensure that immunosuppressive medications are at therapeutic levels - not too low to risk rejection, and not too high to cause dangerous side effects.
Why Regular Monitoring Matters
Transplant recipients require lifelong immunosuppressive therapy to prevent rejection. Each person metabolizes these medications differently, and factors like other medications, diet, and organ function can affect drug levels. Regular blood testing allows healthcare providers to adjust dosages appropriately, maintaining the delicate balance between preventing rejection and avoiding toxicity.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Transplant patients should work closely with their transplant team and follow all prescribed monitoring schedules. Always consult with a healthcare provider for diagnosis and treatment.
