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Treatment and the treatment process

Uric acid

Uric acid is a substance made when cells break down. Its level is watched closely at the start of leukemia treatment.

Last updated: ~2 min read
On a dark navy background, fine glowing pale gold needle-like crystals dissolve into teal light.
Figure 1.Uric acid crystals are prevented.

01Short answer

Every cell contains genetic material — DNA and RNA. When a cell breaks down, this material is turned into purines and then into uric acid. Normally the kidneys remove uric acid in the urine. In leukemia many cells break down quickly, both from the disease itself and when treatment starts, so uric acid can rise sharply (hyperuricaemia). High uric acid can crystallise in the kidney tubules and damage them; a long-term rise causes gout-like joint pain. During treatment uric acid is checked with a blood test, and plenty of fluid plus medicines chosen by the doctor — allopurinol, febuxostat or rasburicase — are used to prevent problems.

02Simple explanation

The source. Uric acid comes from the genetic material of broken-down cells.

In leukemia. When many cells break down, the level rises.

The risk. Crystals can harm the kidneys.

Protection. Fluids and medicines keep the level low.

03Scientific explanation

Metabolism: hypoxanthine and xanthine are converted to uric acid by the enzyme xanthine oxidase. Humans lack urate oxidase, which would turn uric acid into the more soluble allantoin.

Medicines: allopurinol and febuxostat block xanthine oxidase, reducing new uric acid but not removing what is already there; allopurinol interacts with some drugs (such as mercaptopurine and azathioprine). Rasburicase is a recombinant urate oxidase that breaks down existing uric acid quickly; it is not used in G6PD deficiency because of the risk of haemolysis and methaemoglobinaemia.

A laboratory point: in a patient on rasburicase, a blood sample left at room temperature can show falsely low uric acid, so it is sent on ice.

04What happens in the body?

How do crystals form?

When there is too much uric acid in the blood, it can form sharp crystals in the kidneys and joints. Plenty of fluid and medicines prevent this.

From cell to uric acid

The genetic material of cells is broken down step by step, ending as uric acid. In leukemia this process speeds up.

Along a path of glowing nodes, genetic material breaks down step by step into small gold particles.
Figure 2.Genetic material breaks down into uric acid.

An enzyme medicine

Rasburicase quickly breaks down uric acid that has already formed. It is usually given for a short time to people at high risk.

A glowing enzyme shape cuts a pale gold crystal into small teal fragments.
Figure 3.An enzyme medicine breaks down existing uric acid.

05Controlling uric acid

A simplified outline.

Blood test — Uric acid level.1Blood testUric acid level.
Tablet — Reduces new formation.2TabletReduces new formation.
Enzyme — When risk is high.3EnzymeWhen risk is high.
Fluid — Flow through the kidneys.4FluidFlow through the kidneys.
Kidneys protectedNo crystals form.
Regular checksAt the start of treatment.
Short termUsually during the risk period.

06Medicines that lower uric acid

MedicineHow it worksNote
AllopurinolReduces formation of new uric acidRash; interactions
FebuxostatBlocks the same enzymeAn alternative to allopurinol
RasburicaseBreaks down existing uric acidGiven IV; G6PD is checked

* Only your treating doctor decides the medicine, dose and duration.

07Key terms

Uric acid
A breakdown product of purines.
Hyperuricaemia
High uric acid in the blood.
Purines
Building blocks of DNA and RNA.
Xanthine oxidase
The enzyme that makes uric acid.
G6PD deficiency
An inherited enzyme shortage that makes red cells vulnerable.
Gout
Joint inflammation caused by uric acid crystals.

08Key points

  • Uric acid comes from broken-down cells.
  • It is checked at the start of leukemia treatment.
  • A high level can harm the kidneys.
  • Fluids and medicines reduce the risk.
  • If you get a rash, call straight away.
  • Don’t change your diet on your own — talk to your team.

09Frequently asked questions

Can I lower uric acid with food?

In leukemia the main source is broken-down cells, not food; talk to your team about diet.

How long will I take allopurinol?

Usually during the tumour lysis risk period; your doctor decides how long.

Why is a test needed before rasburicase?

In G6PD deficiency this medicine can damage blood cells.

My joint hurts — is it uric acid?

Possibly, but there are other causes too; tell your team.

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. Can I lower uric acid with food?

  2. How long will I take allopurinol?

  3. Why is a test needed before rasburicase?

  4. My joint hurts — is it uric acid?

My questions

12Sources

  1. MedlinePlus. Uric acid – blood
  2. MedlinePlus. Uric Acid Test
  3. MedlinePlus. Allopurinol
  4. MedlinePlus. Febuxostat
  5. Canadian Cancer Society. Tumour lysis syndrome
  6. American Cancer Society. Making Treatment Decisions
  7. National Cancer Institute (NCI). NCI Dictionary of Cancer Terms: port
  8. NHS. Stem cell and bone marrow transplants
  9. MedlinePlus (U.S. National Library of Medicine). Peripherally inserted central catheter - dressing change
  10. MedlinePlus (U.S. National Library of Medicine). Histocompatibility antigen test
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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