👤 By the CinnaRN Clinical Content Team🕐 Updated 2026-08-23🏷️ Physiological Adaptation🔖 Free to read, print, and share
Also known as: TLS · oncologic emergency
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Use this quick-reference guide to spot, treat, and prevent Tumor Lysis Syndrome on the NCLEX. Keep it handy during review and on exam day!
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📒 The 1-minute cheat sheet
📌 Mech
Tumor cells lyse → dump intracellular
Onset 48-72h after chemo starts
🧪 Labs
↑ K+, ↑ phosphate, ↑ uric acid
↓ Ca++ (binds excess phosphate)
🚩 Report
Hyperkalemia → cardiac arrhythmia, peaked T
↓ urine output → AKI
Tetany/seizures from low Ca
✅ Do
Aggressive IV hydration, ↑ fluids
Allopurinol/rasburicase → ↓ uric acid
Monitor I&O, cardiac, electrolytes
📚 Tumor Lysis Syndrome — full study notes
The cheat sheet above is your quick recall card. These notes go deeper — what it is, what to do first, what must be reported, and what to teach.
Tumor lysis syndrome is an oncologic emergency in which rapid destruction of cancer cells, usually after starting chemotherapy for bulky, fast-growing tumors (leukemias, lymphomas), dumps intracellular contents into the blood. This produces hyperkalemia, hyperphosphatemia, hyperuricemia, and a resulting hypocalcemia. The high uric acid and phosphate can crystallize in the kidneys, causing acute kidney injury, and hyperkalemia can cause fatal arrhythmias. Memory aid: high potassium, high phosphate, high uric acid, low calcium.
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Key points
Understand these first
Occurs when chemotherapy rapidly lyses large numbers of tumor cells, releasing potassium, phosphate, and nucleic acids (uric acid).
Electrolyte pattern: hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia.
Hyperkalemia is the most immediately life-threatening abnormality due to cardiac arrhythmia risk.
Uric acid and calcium-phosphate crystals can precipitate in renal tubules, causing acute kidney injury.
Aggressive IV hydration and allopurinol or rasburicase are used to prevent and treat hyperuricemia.
Highest risk is with bulky, rapidly proliferating cancers like acute leukemia and high-grade lymphoma shortly after treatment begins.
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Nursing priorities
What to do, in order
Administer aggressive IV fluids to maintain high urine output and flush uric acid and phosphate.
Give allopurinol or rasburicase as prescribed to lower uric acid.
Monitor potassium and cardiac rhythm closely; treat hyperkalemia promptly.
Monitor electrolytes, calcium, phosphate, uric acid, and renal function (BUN, creatinine, urine output).
Initiate prevention in high-risk clients before and during chemotherapy with hydration and prophylactic medications.
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Red flags — report now
Escalate immediately
Cardiac dysrhythmias from hyperkalemia (peaked T waves, widening QRS) are life-threatening and require emergent treatment.
Decreasing urine output, rising creatinine, or signs of acute kidney injury must be reported immediately.
Report decreased urination, muscle cramps, numbness/tingling, palpitations, or seizures during or after chemotherapy.
Drink fluids as encouraged to support kidney function and flushing.
Understand the importance of lab monitoring and prophylactic medications around chemotherapy.
Know that this risk is highest in the first days after starting treatment for certain cancers.
❓ Tumor Lysis Syndrome: NCLEX FAQs
What are the priority nursing interventions for Tumor Lysis Syndrome?
Administer aggressive IV fluids to maintain high urine output and flush uric acid and phosphate. Give allopurinol or rasburicase as prescribed to lower uric acid. Monitor potassium and cardiac rhythm closely; treat hyperkalemia promptly. Monitor electrolytes, calcium, phosphate, uric acid, and renal function (BUN, creatinine, urine output).
What are the warning signs of Tumor Lysis Syndrome a nurse must report?
Cardiac dysrhythmias from hyperkalemia (peaked T waves, widening QRS) are life-threatening and require emergent treatment. Decreasing urine output, rising creatinine, or signs of acute kidney injury must be reported immediately. Symptomatic hypocalcemia (tetany, seizures, positive Chvostek/Trousseau) requires urgent intervention.
What do I need to know about Tumor Lysis Syndrome for the NCLEX?
Occurs when chemotherapy rapidly lyses large numbers of tumor cells, releasing potassium, phosphate, and nucleic acids (uric acid). Electrolyte pattern: hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia. Hyperkalemia is the most immediately life-threatening abnormality due to cardiac arrhythmia risk. Uric acid and calcium-phosphate crystals can precipitate in renal tubules, causing acute kidney injury.
What patient teaching is important for Tumor Lysis Syndrome?
Report decreased urination, muscle cramps, numbness/tingling, palpitations, or seizures during or after chemotherapy. Drink fluids as encouraged to support kidney function and flushing. Understand the importance of lab monitoring and prophylactic medications around chemotherapy. Know that this risk is highest in the first days after starting treatment for certain cancers.
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Quick Tip
Occurs when chemotherapy rapidly lyses large numbers of tumor cells, releasing potassium, phosphate, and nucleic acids (uric acid).