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Treatment and the treatment process

Electrolytes and fluid

The balance of water and salts (electrolytes) in the body matters for the heart, muscles, nerves and kidneys. It is watched closely during leukemia treatment.

Last updated: ~2 min read
On a dark navy background, a level scale holds a glowing water drop on one side and teal and gold mineral crystals on the other.
Figure 1.A balance of water and salts supports the organs.

01Short answer

Electrolytes are minerals dissolved in the blood that carry an electrical charge: sodium, potassium, chloride, bicarbonate, calcium, magnesium and phosphate. They control nerve and muscle signals, heart rhythm and how water is shared among cells. During leukemia treatment the balance can be upset for several reasons: vomiting and diarrhoea, eating and drinking little, infusions, some medicines (such as diuretics, certain antibiotics and antifungals), kidney injury or tumour lysis syndrome. That is why blood tests, weight and fluid in and out are checked regularly, and losses are replaced with infusions or tablets when the doctor prescribes them.

02Simple explanation

Water and salts. The body needs water and also small "electric" minerals.

Balance. Too much and too little are both harmful.

Checks. Blood tests and weight show the balance.

Correction. The team replaces losses when needed.

03Scientific explanation

Distribution: about two thirds of body water is inside cells and the rest in extracellular fluid. Sodium is mainly outside cells and potassium inside; membrane pumps keep up this difference.

Typical problems in leukemia: hypokalaemia and hypomagnesaemia (losses, amphotericin B, diuretics), hyponatraemia (some cytotoxic drugs, fluid excess), hyperkalaemia and hyperphosphataemia (tumour lysis, kidney failure), hypocalcaemia.

Clinical importance: potassium and magnesium problems raise arrhythmia risk, especially with QT-prolonging medicines; rapid sodium changes can affect the brain, so correction is gradual.

04What happens in the body?

What do electrolytes do?

Every heartbeat and muscle movement relies on sodium, potassium and calcium flowing across cell membranes. When the balance slips, weakness, cramps and rhythm problems can follow.

At the level of the cell

Cells constantly use minerals as "pumps". The kidneys keep the overall balance by removing extra salts and water.

A close-up of a cell membrane with glowing channels letting small gold and teal particles through.
Figure 2.Electrolytes move across the cell membrane.

How can you help?

If the team asks, note how much you drink and pass, and weigh yourself at the same time each day. These simple records say a lot.

A clear water jug, a measuring cup and a blank chart card on a bedside table in daylight.
Figure 3.Recording what you drink helps track the balance.

05How the balance is checked

A simplified outline.

Blood tests — Electrolytes and kidney results.1Blood testsElectrolytes and kidney results.
Weight and fluid — Intake and output recorded.2Weight and fluidIntake and output recorded.
Correction — Infusions or tablets.3CorrectionInfusions or tablets.
Review — The plan changes with results.4ReviewThe plan changes with results.
Stable conditionHeart and muscles protected.
Early detectionProblems seen before symptoms.
Regular checksThroughout treatment.

06Main electrolytes

ElectrolyteWhat it doesWhat imbalance can cause
SodiumFluid balance, nervesHeadache, confusion, weakness
PotassiumHeart rhythm, musclesWeakness, rhythm problems
CalciumBones, muscle contractionCramps, numbness
MagnesiumHeart, nervesTremor, cramps, arrhythmia
PhosphateEnergy, bonesWeakness; excess harms kidneys

* The laboratory sets normal ranges; your doctor explains your results.

07Key terms

Electrolyte
A charged mineral in the blood (sodium, potassium and others).
Hypokalaemia
Low potassium in the blood.
Hyponatraemia
Low sodium in the blood.
Dehydration
Not enough water in the body.
Fluid balance
Fluid taken in compared with fluid lost.
Electrolyte panel
A blood test for the main electrolytes.

08Key points

  • Electrolytes matter for heart and muscles.
  • The balance is checked often during treatment.
  • Vomiting and diarrhoea upset it quickly.
  • Don’t take salt or mineral supplements on your own.
  • Weight and fluid records help the team.
  • Report cramps or an irregular heartbeat straight away.

09Frequently asked questions

Can I take potassium or magnesium myself?

No. Both too little and too much are dangerous; only on your doctor’s prescription.

How much should I drink?

It depends on your treatment and kidney function; your team will tell you.

Why am I weighed every day?

A quick change in weight often means the body is gaining or losing fluid.

Do sports drinks help?

Sometimes, but their sugar and salt content may not suit you; ask 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 take potassium or magnesium myself?

  2. How much should I drink?

  3. Why am I weighed every day?

  4. Do sports drinks help?

My questions

12Sources

  1. MedlinePlus. Fluid and Electrolyte Balance
  2. MedlinePlus. Electrolytes
  3. MedlinePlus. Electrolyte Panel
  4. MedlinePlus. Dehydration
  5. NHS. Blood transfusion
  6. National Cancer Institute (NCI). Adjustment to Cancer: Anxiety and Distress (PDQ®)
  7. MedlinePlus (U.S. National Library of Medicine). Blood Transfusion and Donation
  8. World Health Organization (WHO). Hand hygiene
  9. National Cancer Institute (NCI). Fatigue and Cancer Treatment
  10. Blood (American Society of Hematology), 2022. Diagnosis and management of AML in adults: 2022 recommendations from an international expert panel on behalf of the ELN
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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