Reference — Oncology

Tumor Lysis Syndrome (TLS)

Tumor lysis syndrome is a potentially fatal oncologic emergency caused by the rapid release of intracellular contents following massive cancer cell death. It most commonly occurs within 24–72 hours of initiating cytotoxic chemotherapy in hematologic malignancies with high tumor burden.

Educational use only. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.

Oncologic emergency. TLS requires immediate recognition, aggressive IV hydration, cardiac monitoring, frequent labs, and prompt provider notification. Delay in management can result in fatal cardiac arrhythmia or acute renal failure.

Pathophysiology

When cancer cells die en masse — whether from chemotherapy, radiation, or spontaneously — they release intracellular contents into the bloodstream faster than the kidneys can clear them. The key released substances are:

Potassium

Hyperkalemia → cardiac arrhythmia

Phosphate

Hyperphosphatemia → binds calcium → hypocalcemia

Nucleic acids

Converted to uric acid → hyperuricemia → crystal deposition in renal tubules

Calcium bound by ↑ phosphate

Hypocalcemia → tetany, seizures, arrhythmia

Uric acid and calcium-phosphate crystals precipitate in renal tubules, causing acute kidney injury. AKI reduces the kidneys' ability to excrete potassium, phosphate, and uric acid — creating a dangerous positive feedback loop.

Cairo-Bishop Classification

Laboratory TLS

2 or more of the following within 3 days before or 7 days after initiating chemotherapy:

•Uric acid ≥8 mg/dL (or 25% increase from baseline)
•Potassium ≥6.0 mEq/L (or 25% increase)
•Phosphorus ≥4.5 mg/dL adults (or 25% increase)
•Calcium ≤7.0 mg/dL (or 25% decrease)

Clinical TLS

Laboratory TLS PLUS one or more of the following:

•Creatinine ≥1.5× ULN (acute kidney injury)
•Cardiac arrhythmia or sudden death
•Seizure

Clinical TLS = end-organ dysfunction — significantly higher mortality

High-Risk Tumors

Risk Level	Tumor Types	Rationale
High	Burkitt lymphoma (highest risk), ALL (acute lymphoblastic leukemia), large-volume AML, diffuse large B-cell lymphoma	High proliferative index, large tumor burden, exquisitely chemosensitive — massive rapid cell lysis with treatment
Intermediate	Chronic lymphocytic leukemia (CLL) with high WBC or rapid lymph node regression, mantle cell lymphoma, multiple myeloma	Moderate tumor burden, less rapid proliferation
Lower	Most solid tumors (breast, lung, colon, prostate) — except high-burden sensitive cases	Lower proliferative rate, less dramatic tumor cell lysis response; however, large-burden sensitive solid tumors can still develop TLS

Lab Abnormalities — KPUCA Mnemonic

Letter	Lab	Direction	Critical Consequence
K	Potassium	↑ Hyperkalemia	Ventricular fibrillation, peaked T waves, wide QRS, asystole
P	Phosphorus	↑ Hyperphosphatemia	Calcium-phosphate precipitation, tissue injury, drives hypocalcemia
U	Uric acid	↑ Hyperuricemia	Renal tubular crystal deposition → AKI
C	Calcium	↓ Hypocalcemia	Tetany, Chvostek's sign, Trousseau's sign, seizures, QT prolongation
A	AKI (creatinine)	↑ Creatinine (BUN)	Impaired metabolite clearance → worsens all other electrolyte abnormalities

Prevention Strategies

Intervention	Mechanism	Notes
IV hydration	Dilutes metabolites, increases GFR, promotes renal excretion	2–3 L/m²/day or 200 mL/hr NS. Goal urine output ≥100 mL/hr. Must be started BEFORE chemotherapy in high-risk patients.
Allopurinol	Xanthine oxidase inhibitor — blocks conversion of xanthine to uric acid. Prevents new uric acid formation.	Oral or IV. Given 24–48 hrs before chemotherapy. Does NOT reduce already-elevated uric acid — only prevents further accumulation.
Rasburicase	Recombinant urate oxidase — converts existing uric acid to allantoin (water-soluble). Rapidly lowers uric acid within hours.	Contraindicated in G6PD deficiency (causes severe hemolysis). More effective than allopurinol for treatment (not just prevention). Blood samples must be kept on ice for accurate uric acid measurement.
Urinary alkalinization	Historically used to increase uric acid solubility — now controversial	Not routinely recommended — increases calcium phosphate precipitation risk

Nursing Priorities

✦Aggressive IV hydration BEFORE and DURING chemotherapy — monitor I&O strictly, Foley catheter preferred

✦Continuous cardiac monitoring — hyperkalemia ECG changes: peaked T waves → widened QRS → sine wave → VF

✦Frequent labs: K, PO4, uric acid, Ca, BUN, Cr, CBC every 4–6 hours or per order

✦Daily weights — monitor for fluid overload from aggressive hydration

✦Report immediately: any ECG changes, AMS, tetany, decreased urine output

✦Administer allopurinol or rasburicase per order — verify G6PD status before rasburicase

✦Hold nephrotoxic agents: NSAIDs, contrast dye, aminoglycosides during TLS risk period

✦No potassium-containing IV fluids (D5NS is preferred over LR which contains some potassium)

✦Calcium supplementation: only for symptomatic hypocalcemia — calcium + high phosphate = calciphylaxis risk

✦Dialysis readiness: anticipate that severe, refractory TLS may require emergent hemodialysis

Related Resources

Oncologic Emergencies GuideTLS, SCC, SVCS, hypercalcemia — full clinical detail

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Oncologic Emergency Comparison ChartSide-by-side comparison of all major oncologic emergencies

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Neutropenic Precautions ReferenceFebrile neutropenia — the other common chemo-related emergency

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Chemotherapy Nursing ConsiderationsTLS is most commonly triggered by cytotoxic chemotherapy

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Standards & sources

Fact-checked Jun 21, 2026

This page is written to align with Oncology Nursing Society (ONS) · National Comprehensive Cancer Network (NCCN) · American Society of Clinical Oncology (ASCO). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →