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Kidney Transplant Rejection

Kidney transplant rejection happens when your body’s immune system doesn’t accept your new kidney and reacts by fighting against it. Because your new kidney isn’t your own and contains foreign proteins, your immune system may see it as a threat and attempt to reject or destroy it.

UPMC’s kidney specialists provide personalized, multidisciplinary care for people who have had a kidney transplant — including expert care to treat kidney transplant rejection. Their goal is to stop kidney transplant rejection from progressing and reduce your risk of complications.

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What Is Kidney Transplant Rejection?

Kidney transplant rejection or smoldering rejection happens when your body’s immune system doesn’t accept your new kidney and reacts by fighting against it. Because your new kidney isn’t your own and contains foreign proteins, your immune system may see it as a threat and attempt to reject or damage it.

What are the types of kidney transplant rejection? 

There are two types of kidney transplant rejection based on the timeframe when the rejection occurs.

Types include:

  • Acute rejection — Happens suddenly, usually within a year of transplant, and is most likely to occur within a few weeks. It is caused by white blood cells or antibodies attacking the kidney.
  • Chronic rejection — Happens slowly over time, sometimes years after the transplant, and is more common than acute rejection.

What causes kidney transplant rejection?

Your immune system’s job is to protect you from foreign viruses, bacteria, poisons, and other harmful substances. When you receive a kidney transplant, foreign proteins in your new kidney may alert your immune system to fight against your new kidney because it isn’t your own.

What happens when a person’s body rejects a transplanted kidney?

Kidney transplant rejection happens when your immune system fights against your new kidney by trying to damage the foreign tissue.

What are kidney transplant rejection risk factors and complications?

Kidney transplant rejection risk factors

As part of the transplant evaluation process, your doctors will take steps to reduce your risk of rejection by making sure your new kidney is the best possible match for you. However, even after taking these precautions, rejection can still happen.

You may be at higher risk of kidney transplant rejection if you:

  • Develop an infection that causes kidney damage.
  • Don’t take your anti-rejection medications as prescribed.
  • Don’t attend follow-up appointments.
  • Take medications that cause kidney damage.

Complications of kidney transplant rejection

If left untreated, kidney transplant rejection may cause your new kidney to fail. If your new kidney fails, you will need to go back on dialysis to survive. You may also need to restart the kidney transplant evaluation process so you can be considered for a new kidney.

How can I prevent kidney transplant rejection? 

Not all kidney transplant rejections can be prevented.

However, you can reduce your risk by:

  • Going to all your follow-up appointments.
  • Taking steps to prevent infections.
  • Taking your anti-rejection medications exactly as prescribed.
  • Telling your doctor right away if you start to have symptoms of rejection.

How common is kidney transplant rejection?

Up to 20% of people who have a kidney transplant will have some degree of rejection. However, the degree and severity of rejection varies from person to person and doesn’t always cause kidney failure.

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What Are the Signs and Symptoms of Kidney Transplant Rejection?

Kidney transplant rejection doesn’t always cause symptoms, especially when it happens slowly over time. That’s why it’s important to take your antirejection medications as prescribed and go to all your follow-up appointments so your doctor can check for signs of rejection and start treatment early if needed.

Symptoms of kidney transplant rejection may be similar to symptoms of kidney failure and include:

  • Fatigue.
  • Fever.
  • Flu-like symptoms, such as chills, body aches, and headache.
  • Nausea or loss of appetite.
  • Pain or tenderness near the transplant site.
  • Sudden weight gain due to fluid retention.
  • Swelling in your legs, ankles, or feet.
  • Urinating less than usual.

When should I see a doctor about my kidney transplant rejection symptoms?

If you notice symptoms of kidney transplant rejection, you should schedule an appointment with your doctor right away. Getting early treatment may reduce your risk of kidney failure.

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How Do You Diagnose Kidney Transplant Rejection?

Your doctor will perform a physical exam, talk to you about your symptoms, and order tests to diagnose kidney transplant rejection.

What to expect during your visit

During your visit, your doctor will:

  • Ask about any medications you’re taking.
  • Order tests.
  • Perform a physical exam.
  • Review your health history.

Tests to diagnose kidney transplant rejection

Your doctor may order blood tests to diagnose kidney failure. Blood tests include:

  • Blood urea nitrogen (BUN) — Shows how well your kidneys are filtering urea nitrogen, a waste product, from your blood.
  • Electrolyte and other tests — Checks for imbalances in electrolyte and mineral levels in your body, such as sodium, potassium, and bicarbonate.
  • Estimated glomerular filtration rate (eGFR) — This shows how efficiently your kidneys function based on age, creatinine level, and sex.
  • Serum (blood) creatinine — Shows how well your kidneys are filtering creatinine, a waste product, from your blood.

Other tests include:

  • CT scan — A test that creates images of the organs, bones, and tissues in your body.
  • Kidney biopsy — A procedure that involves taking small pieces of kidney tissue for examination under a microscope to check for signs of disease.
  • MRI — Uses a combination of large magnets, radio frequencies, and a computer to produce detailed images of organs and structures within your body.
  • Ultrasound — Uses sound waves to create images of your organs to check for problems.

Kidney transplant rejection prognosis

The severity of kidney transplant rejection varies from person to person. Kidney transplant rejection doesn’t necessarily mean your new kidney will fail.

Many cases of kidney transplant rejection can be treated with medication adjustments. Your doctor will talk to you about your prognosis and what to expect.

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How Do You Treat Kidney Transplant Rejection?

Kidney transplant rejection is a serious condition that requires immediate treatment. The goal of treatment is to stop kidney transplant rejection from progressing and reduce your risk of complications.

Treatment recommendations may include:

Lifestyle changes

Your care team may provide detailed guidance on how to change your diet and lifestyle to slow the progression of rejection.

Your doctor may recommend:

  • Improving your diet and exercise routines to help you achieve a healthier weight, reduce your blood pressure, and lower your blood sugar. A low-sodium diet is essential.
  • Manage other health conditions, such as diabetes or high blood pressure.
  • Practice good hygiene and avoid sick people to reduce your risk of contracting a cold, flu, or other infection.
  • Restrict certain nutrients in your diet, such as protein, phosphorus, or potassium. Your kidneys may not filter excess amounts of these nutrients from your blood, and they can build up to dangerous levels in your body.

Your doctor may refer you to other medical specialists, such as a registered dietitian, endocrinologist, or cardiologist, to help you manage your health.

Medicine to treat kidney transplant rejection

Lifestyle changes alone are not enough to treat kidney transplant rejection. You will also need to change your immunosuppressant (antirejection) medication regimen. Your doctor will adjust your medications to prevent your immune system from attacking your new kidney. Severe cases of kidney transplant rejection may need to be treated in the hospital.

Other treatments for kidney transplant rejection

If kidney transplant rejection causes your kidney to fail, you will need to go on dialysis to survive. You may also need to be evaluated for another kidney transplant.

Why choose UPMC for kidney transplant rejection care?

When you choose UPMC for kidney transplant rejection care, you will receive:

  • Access to world-class nephrology expertise — Our world-renowned experts treat the full spectrum of kidney diseases using the latest diagnostic and treatment techniques.
  • A full range of treatment options — We'll work with you to develop a treatment plan that slows the progression of your disease as much as possible and improves your quality of life.
  • Multidisciplinary care — We partner with special dialysis clinics, experts in supportive care, and kidney transplant surgeons to ensure you receive complete care.

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By UPMC Editorial Staff. Last reviewed on 2025-04-24.