ConditionWhole body & general
Electrolyte Imbalance
An electrolyte imbalance is when the level of a mineral that carries an electrical charge in the blood, such as sodium, potassium, calcium, magnesium, chloride, phosphate or bicarbonate, is too high or too low. Electrolytes control fluid balance, nerve signals, muscle contraction and heart rhythm. Imbalances are usually caused by vomiting, diarrhea, kidney problems, medicines such as diuretics, or hormone disorders. Mild ones cause tiredness and cramps; severe ones can cause confusion, seizures and dangerous heart rhythms.
Also called: Electrolyte disorder, electrolyte disturbance, electrolyte abnormality, mineral imbalance
At a glance
- What it is
- Too much or too little of a blood mineral such as sodium, potassium, calcium or magnesium.
- Common causes
- Vomiting, diarrhea, heavy sweating, diuretics, kidney disease, hormone problems, drinking too much or too little water.
- Symptoms
- Fatigue, weakness, muscle cramps or twitching, nausea, confusion, palpitations; often none when mild.
- Danger signs
- Seizures, severe confusion, irregular heartbeat, paralysis.
- Diagnosis
- Blood tests (basic metabolic panel), ECG, sometimes urine tests.
- Treatment
- Correct the level carefully by mouth or IV and treat the cause.
When to get help
Call 911 or go to the ER
- Seizures, fainting, severe confusion or being hard to wake
- Palpitations with chest pain, breathlessness or fainting, or a very slow or irregular pulse
- Sudden severe muscle weakness or inability to move the legs
- Vomiting and diarrhea with signs of severe dehydration: no urine for 8 hours or more, very dry mouth, dizziness on standing, or lethargy in a child
See a doctor within a day or two
- Persistent vomiting or diarrhea for more than 24 hours while taking diuretics, ACE inhibitors, ARBs or lithium
- A blood test result your doctor calls significantly abnormal
- New confusion, headache and nausea after drinking very large amounts of water (for example during endurance events)
- Muscle cramps, tingling around the mouth or hand spasms after thyroid or parathyroid surgery
Book a routine appointment
- Frequent muscle cramps, twitching or fatigue
- Taking diuretics or other medicines that affect electrolytes without regular blood tests
- Excessive thirst and urination
Usually safe to manage at home
- Mild cramps or tiredness after heavy sweating that improve with fluids and an oral rehydration drink
What electrolytes do
| Electrolyte | Main jobs | Normal range (approximate) |
|---|---|---|
| Sodium | Fluid balance, nerve signals | 135 to 145 mmol/L |
| Potassium | Heart rhythm, muscle function | 3.5 to 5.0 mmol/L |
| Calcium | Bones, muscle contraction, nerves, clotting | 8.5 to 10.5 mg/dL (total) |
| Magnesium | Muscle and nerve function, heart rhythm | 1.7 to 2.2 mg/dL |
| Chloride | Fluid and acid balance | 98 to 106 mmol/L |
| Phosphate | Bones, energy production | 2.5 to 4.5 mg/dL |
| Bicarbonate | Acid-base balance | 22 to 29 mmol/L |
Laboratory ranges vary slightly. The kidneys, hormones (such as ADH, aldosterone and parathyroid hormone) and diet keep levels tightly controlled.
Common types of electrolyte imbalance
Low sodium (hyponatremia)
The most common imbalance. Causes include diuretics (especially thiazides), heart failure, liver cirrhosis, kidney disease, SIADH (excess water-retaining hormone), some antidepressants, drinking very large amounts of water, and severe vomiting or diarrhea. Symptoms: nausea, headache, confusion, unsteadiness and falls, and in severe or rapid cases, seizures and coma. Correction must be gradual, because raising sodium too fast can damage the brain. See hyponatremia.
High sodium (hypernatremia)
Usually from not drinking enough, especially in older adults, babies and people who cannot access water, or from large water losses. Causes thirst, irritability, confusion and weakness.
Low potassium (hypokalemia)
Caused by vomiting, diarrhea, diuretics, laxative misuse and excess aldosterone. Symptoms: weakness, cramps, constipation, palpitations and abnormal heart rhythms. See hypokalemia.
High potassium (hyperkalemia)
Caused by kidney failure, medicines (ACE inhibitors, ARBs, spironolactone, potassium supplements, NSAIDs), acute kidney injury, tissue breakdown and adrenal insufficiency. Often no symptoms until dangerous; can cause weakness and life-threatening heart rhythms. See hyperkalemia.
Calcium imbalances
- High calcium (hypercalcemia): most often from overactive parathyroid glands or cancer. Causes thirst, frequent urination, constipation, kidney stones, bone pain, tiredness and confusion ("bones, stones, groans and moans").
- Low calcium (hypocalcemia): after thyroid or parathyroid surgery, vitamin D deficiency, low magnesium or kidney disease. Causes tingling around the mouth and fingers, muscle cramps and spasms, and seizures.
Magnesium and phosphate
Low magnesium is common with alcohol use, diarrhea, diuretics and long-term proton pump inhibitor use; it causes cramps, tremor and arrhythmias and makes low potassium and calcium hard to correct. Low phosphate occurs with refeeding after starvation, alcohol use and diabetic ketoacidosis treatment.
Who is at higher risk
- older adults, especially those on several medicines
- babies and young children with vomiting and diarrhea
- people with kidney, heart or liver disease
- people taking diuretics, laxatives or certain psychiatric medicines
- people with eating disorders
- endurance athletes and people working in heat
- people with diabetes, adrenal or thyroid disorders
Symptoms
Many imbalances cause no symptoms and are found on routine blood tests. When present:
- tiredness and weakness
- muscle cramps, twitching or spasms
- numbness or tingling
- nausea, vomiting, constipation or diarrhea
- headache
- confusion, irritability or drowsiness
- fast, slow or irregular heartbeat
- seizures in severe cases
Diagnosis
- Basic metabolic panel: measures sodium, potassium, chloride, bicarbonate, kidney function and glucose.
- Calcium, magnesium and phosphate levels.
- ECG: shows changes from potassium, calcium and magnesium problems.
- Urine tests: help work out whether the kidneys are losing or retaining electrolytes.
- Hormone tests such as thyroid, cortisol, aldosterone and parathyroid hormone when indicated.
Treatment
Treatment depends on which electrolyte, how far it is out of range, how quickly it changed and the cause:
- Mild imbalances: oral rehydration solutions, dietary changes, oral supplements, or adjusting medicines.
- Dehydration: oral rehydration solution, or IV fluids if severe.
- Low sodium: fluid restriction, stopping causative medicines, and carefully controlled IV saline for severe cases.
- High potassium: urgent treatment with calcium to protect the heart, insulin and glucose, medicines that remove potassium, and dialysis if needed.
- Low potassium or magnesium: oral or IV replacement.
- High calcium: IV fluids, medicines that lower calcium, and treatment of the cause.
- Treat the underlying cause: kidney disease, hormone disorders, eating disorders or medicine side effects.
Do not take potassium or other supplements without medical advice, because too much can be dangerous, particularly with kidney disease.
Prevention
- Use oral rehydration solution, not just water, during vomiting and diarrhea, especially for children and older adults.
- During long exercise in heat, drink to thirst and include electrolytes; avoid drinking excessive water.
- Have regular blood tests if you take diuretics, ACE inhibitors, ARBs, lithium or other medicines that affect electrolytes.
- Follow sick day advice for pausing certain medicines when you cannot keep fluids down.
Frequently asked questions
What are the symptoms of an electrolyte imbalance?
Symptoms include tiredness, weakness, muscle cramps or twitching, numbness or tingling, nausea, headache, confusion and an irregular or fast heartbeat. Severe imbalances can cause seizures or dangerous heart rhythms. Mild imbalances often cause no symptoms and are found on blood tests.
What causes an electrolyte imbalance?
Common causes are vomiting, diarrhea, heavy sweating, not drinking enough or drinking too much water, diuretics and other medicines, kidney disease, heart or liver failure, and hormone disorders affecting the adrenal, thyroid or parathyroid glands.
How do you fix an electrolyte imbalance?
Mild imbalances are often corrected with oral rehydration drinks, diet changes or supplements, and by adjusting medicines. Severe imbalances are treated in hospital with carefully controlled IV fluids or medicines. Treating the underlying cause prevents it from happening again.
Can drinking too much water cause an electrolyte imbalance?
Yes. Drinking very large amounts of water in a short time, especially during endurance events, can dilute blood sodium and cause hyponatremia, with headache, nausea, confusion and, in severe cases, seizures. Drinking to thirst and using electrolyte drinks during long exercise reduces the risk.
Are sports drinks good for electrolyte imbalance?
Sports drinks replace some sodium and potassium during long exercise in heat. For vomiting and diarrhea, oral rehydration solutions are better, because they have the right balance of salt and sugar. Sports drinks are high in sugar and not needed for everyday hydration.
Sources
This guide was written from current patient and clinical guidance, including:
- MedlinePlus: Fluid and electrolyte balance
- Merck Manual Professional: Overview of disorders of fluid volume and electrolytes
- National Kidney Foundation: Electrolytes
- Cleveland Clinic: Electrolyte imbalance
- NHS: Hyponatraemia and hyperkalaemia guidance