An electrolytes test is a blood test that measures the charged minerals in your blood — mainly sodium, potassium, and chloride — that keep your body's fluid balance, nerves, muscles, and heartbeat working correctly. It is also called a serum electrolytes test, a "salts" test, or part of a metabolic panel. These minerals are interpreted together and alongside your kidney function (urea and creatinine), because the kidneys are what keep them in balance. This guide explains each value in plain language — what a normal sodium potassium range looks like, and what high and low results actually mean.
Electrolytes Normal Range Chart
A standard electrolytes panel reports the values below. Sodium and potassium are the two that matter most. Reference ranges vary slightly between labs, so always compare each value to the range printed on your own report.
| Electrolyte | Normal Range | Low = | High = |
|---|---|---|---|
| Sodium (Na+) | 135–145 mmol/L | Hyponatremia | Hypernatremia |
| Potassium (K+) | 3.5–5.0 mmol/L | Hypokalemia | Hyperkalemia |
| Chloride (Cl-) | 98–107 mmol/L | Hypochloremia | Hyperchloremia |
| Bicarbonate (HCO3-) | 22–29 mmol/L | Acidosis (acid-base) | Alkalosis (acid-base) |
| Calcium (total) | 8.5–10.5 mg/dL | Hypocalcemia | Hypercalcemia |
Sodium (Na+) — High and Low
Sodium is the main electrolyte in the fluid outside your cells, and it largely reflects your body's water balance and hydration rather than how much salt you eat. The normal range is 135–145 mmol/L.
- Low sodium (below 135 mmol/L) — hyponatremia. This usually means there is too much water relative to sodium in the body. Common triggers are vomiting and diarrhoea, water tablets (diuretics), kidney disease, and some hormone problems. Symptoms can include fatigue, confusion, and muscle weakness.
- High sodium (above 145 mmol/L) — hypernatremia. This most often reflects dehydration — not enough water for the amount of sodium — and is common with fluid loss during hot weather or illness.
Because sodium tracks hydration, it is read together with your potassium, kidney function, and how you feel, rather than from a single number.
Potassium (K+) — Why It Matters Most
Potassium is the electrolyte doctors watch most closely, because it strongly affects your heart rhythm. Even small shifts outside the normal range of 3.5–5.0 mmol/L can change how the heart beats.
- Low potassium (below 3.5 mmol/L) — hypokalemia. Often caused by vomiting, diarrhoea, or water tablets. It can cause muscle weakness or cramps, fatigue, and an irregular or fast heartbeat.
- High potassium (above 5.0 mmol/L) — hyperkalemia. Often linked to kidney disease, uncontrolled diabetes, or certain medicines. It can also disturb the heartbeat.
Chloride, Bicarbonate, and Calcium
The rest of the panel rounds out the picture and helps confirm what sodium and potassium are showing.
- Chloride (Cl-): normal 98–107 mmol/L. Chloride usually moves in step with sodium and helps maintain fluid balance. It is mostly useful read alongside the other values rather than on its own.
- Bicarbonate (HCO3-, sometimes reported as CO2): normal 22–29 mmol/L. Bicarbonate reflects your body's acid-base balance — whether your blood is becoming too acidic or too alkaline. Abnormal values point the doctor toward breathing, kidney, or metabolic causes.
- Calcium (total, often included): normal 8.5–10.5 mg/dL. Calcium is important for muscles, nerves, and bones. It is frequently reported on the same panel and is interpreted alongside the other electrolytes.
What Causes Electrolyte Imbalance?
Electrolyte problems are rarely random — they usually point to a specific cause. The most common ones, especially in Pakistan, are:
- Dehydration — not drinking enough water, particularly during summer heat, concentrates or dilutes the salts in your blood.
- Vomiting and diarrhoea — a very big cause in Pakistan, especially in children and during the hot months. Rapid fluid loss strips out sodium and potassium quickly.
- Kidney disease — the kidneys are what keep electrolytes in balance, so kidney problems are a leading cause of abnormal results.
- Diuretics ("water" tablets) — commonly prescribed for blood pressure and heart conditions, these can lower sodium and potassium.
- Uncontrolled diabetes — high blood sugar can disturb potassium and fluid balance.
- Some hormone problems — conditions affecting the glands that regulate salt and water.
Because these minerals depend on the kidneys, an electrolytes report is almost always read together with kidney function tests (urea and creatinine).
Symptoms of Electrolyte Imbalance
Mild imbalances may cause no symptoms and are picked up only on a blood test. When symptoms do appear, they commonly include:
- Muscle weakness or cramps
- Fatigue
- Irregular or fast heartbeat
- Confusion
- Seizures in severe cases
How Much Does an Electrolytes Test Cost in Pakistan?
| Test | Approximate Price (2026) |
|---|---|
| Serum electrolytes (sodium, potassium, chloride) | Rs. 600-1,500 |
Prices vary between labs and cities. Bicarbonate and calcium may be reported on the same panel or ordered separately depending on the lab.
Track Your Electrolytes Over Time
Upload your lab reports to MedVault and see how your sodium, potassium, and other values trend across months. AI flags when values move out of range and explains what it means.
Try MedVault Free →Frequently Asked Questions
What is the normal range for sodium and potassium?
For most adults, normal sodium is 135 to 145 mmol/L and normal potassium is 3.5 to 5.0 mmol/L (mmol/L is the same as mEq/L for these). Sodium mostly reflects hydration and water balance, while potassium is critical for a steady heartbeat. Ranges vary slightly by lab, so compare each value to the range on your own report.
What does low sodium mean?
A sodium below 135 mmol/L is called hyponatremia. It usually means too much water relative to sodium, rather than simply too little salt. Common causes include vomiting and diarrhoea, water tablets (diuretics), kidney disease, and some hormone problems. Symptoms can include fatigue, confusion, muscle weakness, and in severe cases seizures, so let a doctor review it.
What does high potassium mean?
A potassium above 5.0 mmol/L is hyperkalemia. Because potassium strongly affects heart rhythm, a high level matters more than most other electrolytes. Common causes include kidney disease, uncontrolled diabetes, and some medicines. A potassium above 6.0 mmol/L is a medical emergency and needs urgent care.
What causes an electrolyte imbalance?
The most common causes are dehydration and fluid loss from vomiting and diarrhoea — a big cause in Pakistan, especially in children and during summer heat. Others include kidney disease, water tablets (diuretics), uncontrolled diabetes, and some hormone problems. Because these minerals depend on kidney function, they are read alongside urea and creatinine.
What are the symptoms of low potassium?
Low potassium (hypokalemia, below 3.5 mmol/L) can cause muscle weakness or cramps, fatigue, and an irregular or fast heartbeat, and in severe cases confusion or seizures. Because potassium controls heart rhythm, a low level can be dangerous and needs prompt medical care. It is usually checked together with your other electrolytes and kidney function.