NurseSavvy™
Log inSign Up

Hematology, Oncology & Immunology · Topic 14 of 26

Tumor Lysis Syndrome

Oncology · metabolic emergency

Tumor Lysis Syndrome

Dying tumor cells flood the blood with potassium, phosphate and uric acid: in high-risk cancers, hydrate hard and lower uric acid before chemotherapy starts.

Key numbers
Laboratory TLS: 2 or more abnormal valuesuric acid ≥ 8 mg/dL
Clinical TLS: plus AKI, arrhythmia or seizureCr ≥ 1.5 × ULN
Hydrate aggressively before chemotherapyUO ≥ 100 mL/h
Rasburicase: high risk or high uric acid0.2 mg/kg IV
01 · Defined byLaboratory TLS: 2 or more abnormal values

Cairo-Bishop laboratory TLS = ≥ 2 of: uric acid ≥ 8 mg/dL, potassium ≥ 6 mEq/L, phosphorus ≥ 4.5 mg/dL (adults), calcium ≤ 7 mg/dL, from 3 days before to 7 days after therapy.

02 · DoHydrate aggressively before chemotherapy

Start vigorous IV hydration before chemotherapy — about 2.5–3 L/m² per day in the highest-risk patients — targeting urine output of at least 100 mL/hour (2 mL/kg/hour); add a loop diuretic only after volume repletion.

03 · GiveRasburicase: high risk or high uric acid

Rasburicase (recombinant urate oxidase, 0.2 mg/kg IV over 30 minutes daily for up to 5 days) is first line for high-risk patients or established hyperuricemia because it degrades uric acid already formed.

01

What it is

Core idea
Uric acid and calcium phosphate crystals cause AKIReleased nucleic acids become uric acid, which precipitates in the renal tubules; high phosphate binds calcium, depositing calcium phosphate in kidneys and heart and causing hypocalcemia and tetany.
02

Causes & risk factors

Why it happens
Highest risk: Burkitt, acute leukemia, bulky tumors must knowHighest TLS risk: Burkitt and other high-grade lymphomas and acute leukemias (rapidly proliferating, chemosensitive), bulky disease, LDH > 2 × ULN, high uric acid or renal impairment at presentation.
03

Diagnosis & monitoring

Work-up
Clinical TLS: plus AKI, arrhythmia or seizure must knowClinical TLS = laboratory TLS plus at least one of: creatinine ≥ 1.5 × the upper limit of normal (acute kidney injury), cardiac arrhythmia or sudden death, or seizure.
On rasburicase, send uric acid on iceRasburicase keeps degrading uric acid in the tube at room temperature: collect samples in prechilled heparin tubes, keep them in an ice-water bath and assay within 4 hours.
04

Do right now

In this order
First moves
1
Highest risk: Burkitt, acute leukemia, bulky tumors
→
2
Hydrate aggressively before chemotherapyUO ≥ 100 mL/h
→
3
Rasburicase: high risk or high uric acid0.2 mg/kg IV
→
4
Hyperkalemia: monitor the ECG, treat at once
Why each step
Highest risk: Burkitt, acute leukemia, bulky tumorsHighest TLS risk: Burkitt and other high-grade lymphomas and acute leukemias (rapidly proliferating, chemosensitive), bulky disease, LDH > 2 × ULN, high uric acid or renal impairment at presentation.
Hydrate aggressively before chemotherapyStart vigorous IV hydration before chemotherapy — about 2.5–3 L/m² per day in the highest-risk patients — targeting urine output of at least 100 mL/hour (2 mL/kg/hour); add a loop diuretic only after volume repletion.
Rasburicase: high risk or high uric acidRasburicase (recombinant urate oxidase, 0.2 mg/kg IV over 30 minutes daily for up to 5 days) is first line for high-risk patients or established hyperuricemia because it degrades uric acid already formed.
Hyperkalemia: monitor the ECG, treat at onceHyperkalemia can cause fatal arrhythmias: monitor the ECG and treat by level with IV calcium, insulin plus glucose and potassium binders; dialysis thresholds are lower because tumor cells keep releasing potassium.
05

Management

Orders
Allopurinol prevents new uric acid onlyAllopurinol (200–400 mg/m² daily, max 600 mg/day), started at least 2 days before chemotherapy, blocks new uric acid production but does not lower uric acid already present — suited to lower-risk patients.
Treat hypocalcemia only if symptomaticDo not treat asymptomatic hypocalcemia — calcium raises calcium phosphate precipitation. Give the lowest effective IV calcium dose for tetany, arrhythmia or seizure, whatever the phosphate level.
Lower the threshold for dialysis in TLSUse standard dialysis indications but act earlier — rapid potassium release, oliguria, or symptomatic hypocalcemia from hyperphosphatemia; continuous therapies clear phosphate well. Hyperuricemia alone rarely needs dialysis when rasburicase is available.
06

Red flags & don'ts

Avoid harm
No rasburicase in G6PD deficiency avoidRasburicase is contraindicated in G6PD deficiency (hemolysis, methemoglobinemia); screen patients at higher risk, such as those of African or Mediterranean ancestry, before giving it.
Do not alkalinize the urine avoidAvoid routine urinary alkalinization with sodium bicarbonate: it promotes calcium phosphate precipitation in the kidneys, and phosphate is harder to control than uric acid when rasburicase is available.
07

Allopurinol or rasburicase?

Commonly confused
ActionBlocks new uric acid production (xanthine oxidase)
UsePrevention in lower-risk patients
Dose200–400 mg/m² daily, max 600 mg/day
StartAt least 2 days before chemotherapy
Key cautionDoes not lower uric acid already formed
08

More detail

Reference
Show 4 reference facts
TLS occurs mainly in leukemias and lymphomas, uncommonly after solid-tumor treatment, and can follow immune therapies such as CAR-T cells or bispecific antibodies.
Rasburicase is typically started 4–24 hours before the first chemotherapy dose; it is labeled for a single course and can cause anaphylaxis, hemolysis and methemoglobinemia.
In children the Cairo-Bishop phosphorus threshold is ≥ 6.5 mg/dL rather than the adult ≥ 4.5 mg/dL.
When TLS risk is borderline, assign the higher-risk category; oliguria, dehydration, hypotension, acidic urine and nephrotoxins all raise risk.
Pearl

Three up, one down: potassium, phosphate and uric acid rise; calcium falls.

Sources · Howard SC, Jones DP, Pui CH. The Tumor Lysis Syndrome. N Engl J Med 2011;364:1844–1854 · Merck Manual Professional — Management of Adverse Effects of Cancer Therapy (tumor lysis syndrome) · Elitek (rasburicase) prescribing information — DailyMed (updated Jul 2026) · Pina Cabral J et al. Spontaneous Tumor Lysis Syndrome in Prostate Cancer. Cureus 2021 (Table 2: Cairo-Bishop classification) · Cairo MS, Bishop M. Tumour lysis syndrome: new therapeutic strategies and classification. Br J Haematol 2004;127:3–11 — abstract via Europe PMC · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).