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Treatment and the treatment process

Tumour lysis syndrome

When treatment destroys many leukemia cells in a short time, their contents enter the blood. This can strain the kidneys and heart, but in most cases it can be prevented.

Last updated: ~2 min read
On a dark navy background, stylised leukemia cells gently break apart, releasing red, gold and teal particles into a stream.
Figure 1.Breaking cells release their contents into the blood.

01Short answer

Tumour lysis syndrome (TLS) happens when large numbers of cancer cells break down quickly. The cells release potassium, phosphate and nucleic acids into the blood; the nucleic acids are turned into uric acid. If the kidneys cannot clear this load in time, potassium, phosphate and uric acid rise and calcium falls. This can cause kidney injury, heart rhythm problems and seizures. Risk is higher in acute leukemias (especially with a high white cell count), Burkitt lymphoma and when starting some targeted drugs (such as venetoclax). So risk is assessed before treatment, plenty of IV fluid is given, uric acid–lowering medicines (allopurinol or rasburicase) are used, and blood tests are checked often in the first days.

02Simple explanation

Cells break down. Treatment destroys leukemia cells.

Contents enter the blood. Potassium, phosphate and uric acid rise.

The kidneys are loaded. They may struggle to clear it all.

Prevention. Fluids, medicines and tests reduce the risk.

03Scientific explanation

Laboratory and clinical TLS: under the Cairo–Bishop classification, laboratory TLS is based on defined changes in uric acid, potassium, phosphate and calcium; clinical TLS adds a rise in creatinine, arrhythmia or seizures.

Mechanism: breakdown of purine nucleotides via xanthine oxidase produces uric acid, which can crystallise in the kidney tubules. Phosphate binds calcium, forming calcium phosphate deposits and causing hypocalcaemia.

Prevention and treatment: according to risk — hydration, allopurinol (reduces uric acid formation) or rasburicase (breaks down existing uric acid; contraindicated in G6PD deficiency), electrolyte correction and ECG monitoring; dialysis in severe cases. With drugs such as venetoclax, the dose is increased step by step.

04What happens in the body?

What happens?

When treatment starts working, many leukemia cells break down at once and release their contents into the blood. It is a sign treatment is working, but a sudden load for the body.

How are the kidneys protected?

Plenty of IV fluid increases flow through the kidneys and helps clear the substances quickly. Medicines keep uric acid low.

Glowing kidneys receive a stream of particles, surrounded by a teal protective shield of flowing water.
Figure 2.Plenty of fluid protects the kidneys.

Why is the heart watched?

Changes in potassium and calcium can affect heart rhythm, so an ECG or monitor is used when risk is high.

On a dark background, an abstract heart outline with a steady gold rhythm wave as red ripples calm.
Figure 3.Heart rhythm is protected from potassium changes.

05How TLS is prevented

A simplified outline.

Risk assessment — Leukemia type, tests, kidneys.1Risk assessmentLeukemia type, tests, kidneys.
Hydration — Before and during treatment.2HydrationBefore and during treatment.
Frequent tests — In the first days.3Frequent testsIn the first days.
Heart monitoring — When needed.4Heart monitoringWhen needed.
PreventionIn most cases.
Early detectionChanges in blood tests.
Urgent treatmentStraight away if needed.

06What changes in TLS

MeasureChangeWhat it can cause
PotassiumRisesRhythm problems, weakness
PhosphateRisesKidney injury
Uric acidRisesCrystals in the kidneys
CalciumFallsCramps, numbness, arrhythmia
CreatinineMay riseWorsening kidney function

* Your team sets the limits and treatment based on your results.

07Key terms

Tumour lysis
Breakdown of tumour cells.
Uric acid
A breakdown product of nucleic acids.
Hyperkalaemia
High potassium in the blood.
Allopurinol
A medicine that reduces uric acid formation.
Rasburicase
An enzyme medicine that breaks down uric acid.
Hydration
Giving plenty of fluid.

08Key points

  • TLS comes from many cells breaking down fast.
  • Risk is higher in acute leukemias.
  • In most cases it is prevented.
  • Blood tests are frequent in the first days.
  • The kidneys are protected with plenty of fluid.
  • Report symptoms straight away.

09Frequently asked questions

Does TLS mean treatment is going badly?

No — it shows cells are dying quickly; the aim is to make this safe.

Why are blood tests taken so often?

Potassium and other results can change within hours; seeing it early matters.

Which foods should I limit?

If potassium or phosphate is high, your team will give personal dietary advice; don’t start a diet on your own.

Will I need dialysis?

Rarely, if the kidneys struggle; it is usually temporary.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Does TLS mean treatment is going badly?

  2. Why are blood tests taken so often?

  3. Which foods should I limit?

  4. Will I need dialysis?

My questions

12Sources

  1. National Cancer Institute (NCI). Definition of tumor lysis syndrome – NCI Dictionary of Cancer Terms
  2. Canadian Cancer Society. Tumour lysis syndrome
  3. Memorial Sloan Kettering Cancer Center. About Tumor Lysis Syndrome (TLS)
  4. MedlinePlus. Allopurinol
  5. National Cancer Institute (NCI). Diarrhea and Cancer Treatment
  6. National Cancer Institute (NCI). Depression (PDQ) – Patient Version
  7. WHO / IARC. WHO Classification of Tumours, 5th edition — Haematolymphoid Tumours
  8. American Cancer Society. Leukemia in Children
  9. NHS. Chronic lymphocytic leukaemia — Treatment
  10. National Cancer Institute (NCI). Clinical Trials Information for Patients and Caregivers
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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