Tumor lysis syndrome is a group of potentially life-threatening conditions that may happen within hours after cancer treatment. The condition can rapidly become a medical emergency. Treatment is medication and IV hydration. Healthcare providers focus on preventing tumor lysis syndrome before it can happen.
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Tumor lysis syndrome (TLS) is a serious complication of cancer treatment. In TLS, dying cancer cells flood your bloodstream with toxic substances, as well as high levels of uric acid, potassium and phosphate. You also have low calcium levels. This condition is a medical emergency because it may cause kidney failure and cardiac arrest.
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Tumor lysis syndrome may develop during treatment or within 12 to 72 hours after you receive treatment. Your care team will check on issues during and right after your treatment. But if you’re recovering at home, get help right away if you have the following symptoms:
Receiving chemotherapy for cancer is the most common cause. But you may develop tumor lysis syndrome if your treatment includes steroids, targeted therapy or immunotherapy.
TLS happens when substances inside dying cancer cells get into your bloodstream and flow into your kidneys. Normally, your kidneys filter and get rid of these substances. When cancer treatment kills lots of cancer cells, your kidneys can’t filter substances fast enough. You then develop the following conditions:
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Not everyone treated for cancer will develop tumor lysis syndrome. It most often affects people receiving treatment for certain types of cancer that grow quickly, including:
Some health issues and conditions increase your risk of tumor lysis syndrome. Your cancer care team will take steps to reduce your risk before you receive treatment. Issues that may increase risk include:
Healthcare providers diagnose tumor lysis syndrome by checking for changes in your uric acid, phosphorus levels, potassium levels and calcium levels. Providers may use the term “tumor lysis syndrome hallmarks” or “tumor lysis syndrome cardinals.” They’ll do blood tests and imaging tests.
Your care team will do the following blood tests:
They’ll do imaging tests to look for issues with your kidneys that TLS may cause. Sometimes, you may get a CT scan to determine the amount of cancer you may have.
Your care team will do urinalysis to check for abnormalities in your pee and an ECG to look for signs of an irregular heartbeat.
Your cancer care team treats the syndrome conditions with medication, dialysis and diuretics:
Yes, but tumor lysis syndrome can be life-threatening. That’s why your cancer care team will constantly check to see how your body reacts to treatment. Your team will act right away to manage any signs of TLS. The type of cancer you have and your overall health affect the impact that TLS may have. As with all cancer treatments, your care team will explain the risks and side effects of the treatment you’ll receive.
Cancer treatment can be tough, especially when it works so well that it rapidly kills cancer cells and causes tumor lysis syndrome. Before you start treatment, your cancer care team will let you know if there’s a chance treatment will cause tumor lysis syndrome. If you’re at risk, they’ll take steps to prevent it. Your team will understand if you have questions and concerns. Don’t hesitate to ask if you need more information about what to expect.
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Last reviewed on 10/06/2025.
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