Organ Transplant Rejection Blood Test

What is Organ Transplant Rejection?

Organ transplant rejection occurs when the immune system recognizes a transplanted organ as foreign tissue and attacks it. It is caused by the recipient's T-cells and antibodies targeting antigens on the donor organ that differ from the recipient's own tissue markers. The Sirolimus Blood Level Test is the most important test for preventing rejection because it ensures immunosuppressive medications remain at therapeutic levels.

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What causes organ transplant rejection?

Organ transplant rejection is caused by the recipient's immune system recognizing the transplanted organ as foreign tissue and mounting an attack against it. The recipient's T-cells and antibodies target specific proteins called human leukocyte antigens (HLA) on the donor organ that differ from the recipient's own tissue markers. This immune response can occur at any time after transplantation, which is why lifelong immunosuppressive therapy is necessary to prevent the immune system from destroying the new organ.

What is the best test for organ transplant rejection?

The Sirolimus Blood Level Test is the most important test for preventing organ transplant rejection because it measures the concentration of sirolimus immunosuppressant medication in your blood. While tissue biopsies directly diagnose rejection, monitoring drug levels is essential for prevention. The test ensures your immunosuppressive medication stays within the therapeutic range—high enough to prevent your immune system from attacking the transplanted organ, but low enough to avoid dangerous side effects like infections, kidney damage, or increased cancer risk. Your transplant team uses these results to adjust your medication dosage, maintaining the delicate balance needed for long-term transplant success.

When should I get tested for organ transplant rejection?

You should get tested if you are taking sirolimus or other immunosuppressive medications after receiving an organ transplant. Regular monitoring is essential, especially during the first year after transplantation when rejection risk is highest, after any medication dose changes, if you start or stop other medications that might interact with your immunosuppressants, or if you experience symptoms like fever, pain or tenderness over the transplant site, decreased organ function, or fatigue. Your transplant team will establish a testing schedule based on your individual needs, typically ranging from weekly tests initially to monthly or quarterly once stable.

What are the symptoms of organ transplant rejection?
Symptoms of organ transplant rejection vary depending on which organ was transplanted. Common signs include fever, flu-like symptoms, pain or tenderness over the transplanted organ, and decreased organ function. Kidney transplant rejection may cause decreased urine output, weight gain, and swelling. Liver transplant rejection can cause jaundice, dark urine, and abdominal pain. Heart transplant rejection may present as shortness of breath, fatigue, and irregular heartbeat. Lung transplant rejection often causes shortness of breath, cough, and decreased oxygen levels. Many rejection episodes occur without noticeable symptoms, which is why regular monitoring through blood tests and scheduled biopsies is critical for catching rejection early when it is most treatable.
Who is at risk for organ transplant rejection?
All organ transplant recipients are at risk for rejection, but certain factors increase this risk. Higher risk occurs with greater HLA mismatch between donor and recipient, younger recipient age, previous transplant rejection episodes, inadequate immunosuppressive medication levels, missed medication doses, and presence of pre-existing antibodies against the donor organ. African American and Hispanic recipients statistically face higher rejection rates. Additional risk factors include infections that activate the immune system, certain medications that interfere with immunosuppressants, pregnancy, and stopping or reducing immunosuppressive therapy without medical supervision. Even with perfect medication adherence, chronic rejection can develop over years due to gradual immune system activation.
What happens if organ transplant rejection is left untreated?
Untreated organ transplant rejection leads to progressive organ damage and eventual graft failure, meaning the transplanted organ stops functioning. Acute rejection that is not caught and treated quickly can cause permanent scarring and damage to the organ. Chronic rejection develops slowly over months or years, causing gradual loss of organ function that may be irreversible even with treatment. Once the transplanted organ fails completely, you will need to return to alternative treatments—dialysis for kidney transplants, mechanical support for heart transplants, or oxygen therapy for lung transplants—and be placed back on the transplant waiting list. Graft failure significantly impacts quality of life and survival, making regular monitoring and early intervention essential for long-term transplant success.
Can organ transplant rejection be diagnosed with a blood test?
Blood tests cannot directly diagnose organ transplant rejection, but they play a crucial role in preventing rejection and monitoring transplant health. The Sirolimus Blood Level Test and similar tests for other immunosuppressants ensure medications remain at therapeutic levels to prevent rejection. Some blood tests can indicate possible rejection by detecting donor-specific antibodies or measuring organ function markers like creatinine for kidneys or liver enzymes for liver transplants. However, definitive diagnosis of acute rejection requires a tissue biopsy of the transplanted organ examined under a microscope. Blood tests serve as an early warning system and guide medication management, while biopsies confirm rejection when suspected based on symptoms or abnormal blood work.
How is organ transplant rejection treated?
Organ transplant rejection is treated by intensifying immunosuppressive therapy to suppress the immune system's attack on the transplanted organ. Acute rejection typically requires high-dose intravenous corticosteroids for several days, and if this fails, more powerful immunosuppressants like antithymocyte globulin or monoclonal antibodies may be used. After treating the rejection episode, your maintenance immunosuppressive medications are usually increased or adjusted to prevent future rejection. Chronic rejection is more difficult to treat and focuses on optimizing immunosuppression and managing complications. Throughout treatment, blood tests monitor medication levels and organ function, while follow-up biopsies confirm treatment success. Early detection and prompt treatment provide the best chance of reversing rejection and preserving the transplanted organ.
How can I prevent organ transplant rejection?
Preventing organ transplant rejection requires strict adherence to your immunosuppressive medication regimen—take every dose exactly as prescribed, at the same times each day, and never skip or stop medications without consulting your transplant team. Attend all scheduled follow-up appointments and blood tests to monitor drug levels and organ function. Avoid people who are sick and practice good hygiene to prevent infections that can trigger immune activation. Maintain a healthy lifestyle with balanced nutrition, regular exercise, adequate sleep, and stress management. Avoid grapefruit and grapefruit juice, which interfere with many immunosuppressants. Inform all healthcare providers that you are a transplant recipient before starting any new medications or supplements. Report any symptoms or concerns to your transplant team immediately rather than waiting for your next appointment.
What can I do at home to support my transplanted organ?
Supporting your transplanted organ at home starts with meticulous medication management—use pill organizers, set phone alarms, and keep a medication diary to ensure perfect adherence. Monitor and record your vital signs as directed by your transplant team, which may include daily weight, blood pressure, temperature, and blood glucose levels. Maintain excellent hygiene including frequent handwashing, safe food preparation, and avoiding crowded places during high illness seasons. Stay well-hydrated, eat a balanced diet rich in fruits and vegetables while following any dietary restrictions specific to your transplant, and engage in regular gentle exercise as approved by your doctor. Avoid tobacco, limit alcohol strictly as advised, and protect your skin from sun exposure since immunosuppressants increase skin cancer risk. Keep a health journal documenting any symptoms, medication changes, or concerns to share with your transplant team.
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If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.
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