An electrolyte panel is a blood test that measures the main charged minerals in your blood: sodium, potassium, chloride and bicarbonate, which appears on reports as CO2. These four electrolytes control how much water your body holds, keep your heart and muscles working and keep your blood from becoming too acidic or too alkaline. Doctors order the test during routine checkups, when you feel unwell with vomiting, weakness or confusion and when you take medicines that can shift electrolyte levels. Most results that fall slightly outside the range are not dangerous, but a few patterns need prompt attention.
In this article you’ll learn what each electrolyte does, the typical adult ranges, what low and high results can mean, the most common causes of an imbalance, how to prepare for the test and when a result calls for a doctor.
What an electrolyte panel measures
Electrolytes are minerals that carry an electric charge when they dissolve in body fluids. The standard panel focuses on four of them. Sodium helps control the amount of fluid in your body, potassium keeps your cells, heart and muscles working properly, chloride helps maintain blood volume and blood pressure, and bicarbonate keeps your blood pH balanced, according to MedlinePlus. Cleveland Clinic notes that some laboratories add calcium, magnesium and phosphate, so the exact list depends on what your doctor ordered.
The same four electrolytes are also part of larger panels. If your report also shows glucose, calcium, BUN and creatinine, you had a basic metabolic panel; to read those extra lines, open our basic metabolic panel guide. If it also lists liver tests, you had a comprehensive panel; to decode those results, use our comprehensive metabolic panel guide.
Why your doctor orders an electrolyte panel
Cleveland Clinic lists four main reasons: routine blood work, finding the cause of symptoms that may come from an imbalance, diagnosing conditions that disturb electrolytes and checking whether treatment is working. Typical triggers include nausea or vomiting, diarrhea, weakness, muscle cramps, confusion, an irregular heartbeat and swelling. The test is also repeated regularly in people who take diuretics or certain blood pressure medicines, and in people with kidney, heart or liver disease.
Electrolyte panel normal ranges
Each laboratory sets its own reference range, which can vary with age, sex and the testing method, so the range printed on your report is the one that counts. The table uses the general adult ranges published by Cleveland Clinic and the medical names for low and high values that you may see on a report or in a doctor’s note.
| Elettrolita | Funzione principale | Intervallo tipico negli adulti | Too low | Too high |
|---|---|---|---|---|
| Sodium (Na) | Controls body water, nerve and muscle function | Da 135 a 145 mmol/L | Iponatremia | Ipernatriemia |
| Potassium (K) | Heart rhythm, nerve and muscle function | 3.6 to 5.5 mmol/L | Ipokaliemia | Iperkaliemia |
| Chloride (Cl) | Blood volume, blood pressure and fluid balance | 97 to 105 mmol/L | Ipocloremia | Ipercloriemia |
| Bicarbonate (CO2) | Acid-base (pH) balance | 22–29 mmol/L | Can signal acidosis | Can signal alkalosis |
The units mmol/L and mEq/L give the same number for these four electrolytes, so a sodium of 140 mmol/L is also 140 mEq/L. A value just outside the range is common in healthy people; Cleveland Clinic stresses that an out-of-range result does not necessarily mean you have a problem that needs treatment.
Sodium: what low and high results mean
Low sodium (hyponatremia)
A healthy blood sodium level is between 135 and 145 mmol/L, and a result below 135 is called hyponatremia, according to Mayo Clinic. It usually means there is too much water for the amount of sodium rather than a lack of salt in the diet. Mayo Clinic lists diuretics, especially thiazides, certain antidepressants and pain medicines, heart failure, kidney or liver disease, hormone problems, severe vomiting or diarrhea and drinking large amounts of water during endurance events among the causes. Mild cases may cause no symptoms; lower levels can cause nausea, headache, confusion, fatigue, muscle cramps and, in severe cases, seizures.
When sodium falls slowly over days, the body adapts and symptoms are milder. A rapid drop is more dangerous because brain cells swell. To understand your number in detail, read our guida all'esame del sodio nel sangue.
High sodium (hypernatremia)
A high sodium most often means the body has lost more water than salt, for example through dehydration, fever, heavy sweating or not being able to drink enough, which is common in frail older adults. Chloride often rises at the same time. Thirst, a dry mouth, fatigue and confusion are typical signs. Learn the warning signs of fluid loss by reading our dehydration guide.
Potassium: what low and high results mean
Low potassium (hypokalemia)
Cleveland Clinic describes a potassium between 3 and 3.5 mmol/L as mild hypokalemia and a value below 3 mmol/L as severe. Common causes are vomiting, diarrhea and laxative use, diuretics, some antibiotics, insulin and corticosteroids, heavy sweating, alcohol use disorder, adrenal disorders and low magnesium. Mild cases may cause no symptoms, while lower levels can cause muscle weakness or cramps, tiredness, constipation, palpitations and abnormal heart rhythms. Because low magnesium can itself cause low potassium, doctors often check both; see our guida all'esame del magnesio nel sangue.
High potassium (hyperkalemia)
According to Cleveland Clinic, hyperkalemia begins above 5.5 mmol/L, and levels above 6.5 mmol/L can cause heart problems that need immediate care. Kidney disease is the most common cause, because damaged kidneys remove less potassium. Potassium supplements, a very high potassium intake and some blood pressure medicines that reduce potassium removal also contribute, as do Addison’s disease, diabetes, heart failure and large burns. Mild high potassium often causes no symptoms; severe cases can cause palpitations, an irregular heartbeat, chest pain and muscle weakness.
A high potassium is also the result most likely to be false. Potassium can leak out of blood cells if the sample is difficult to draw or left too long before processing, so an unexpected high value in someone who feels well is usually repeated first. For a deeper look, consult our guida all'esame del potassio nel sangue.
Chloride and CO2: the acid-base pair
Cloro
Cleveland Clinic links high chloride to dehydration, kidney disease, Cushing’s syndrome and certain types of acidosis, and low chloride to heart failure, lung disease such as emphysema, Addison’s disease and metabolic alkalosis, which often follows repeated vomiting. Chloride usually moves in the same direction as sodium, so a lone chloride change is read alongside sodium and bicarbonate. Check what your value suggests by reading our guida all'esame del cloruro nel sangue.
CO2 (bicarbonate)
The CO2 line measures bicarbonate, the main buffer against acid in the blood. Cleveland Clinic lists ketoacidosis in diabetes, kidney disorders, metabolic acidosis, shock and Addison’s disease among the causes of a low value, and alkalosis, lung disease such as COPD, Cushing’s syndrome and kidney disorders among the causes of a high value. A low CO2 with fast breathing, nausea or confusion needs prompt care. To understand your result, explore our bicarbonate blood test guide.
Many reports also print an anion gap, calculated from sodium, chloride and bicarbonate. A high gap can help doctors narrow down the cause of acidosis; for the details, review our guida al test del gap anionico nel sangue.
Common causes of an electrolyte imbalance
MedlinePlus lists dehydration, kidney disease, heart disease, diabetes, liver disease, acidosis and alkalosis among the main causes of abnormal electrolytes, along with medicines such as diuretics, steroids, large amounts of antacids, some antibiotics and chemotherapy. The table summarizes how common situations tend to show up on the panel; real results often mix several effects.
| Situazione | Typical effect on the panel |
|---|---|
| Vomito ripetuto | Low potassium, low chloride, high CO2 |
| Severe or long-lasting diarrhea | Low potassium, low CO2 |
| Diuretics (water pills) | Low sodium and low potassium, especially with thiazides |
| Disidratazione | High sodium and high chloride |
| Drinking large amounts of water during endurance exercise | Low sodium |
| Advanced kidney disease | High potassium, low CO2 |
| Diabetic ketoacidosis | Low CO2, often with high glucose on a larger panel |
| Addison’s disease | Low sodium, high potassium, low CO2 |
Long-term conditions often sit behind a recurring imbalance. Kidney disease is the leading cause of high potassium; to follow it over time, study our guida alla malattia renale cronica. Heart failure and its treatment frequently shift sodium and potassium; to learn how, explore our heart failure diagnosis guide. Blood pressure medicines are among the most common reasons for repeat testing; for the bigger picture, read our guida all'ipertensione arteriosa.
How to prepare for an electrolyte panel and what comes next
Cleveland Clinic says fasting is usually not required, unless other tests such as blood sugar or cholesterol are drawn at the same time. Drinking your normal amount of fluid helps, and smoking or vaping just before the draw is best avoided. Keep taking your medicines unless told otherwise, and tell the person ordering the test about diuretics, potassium supplements, recent vomiting or diarrhea and any intense exercise. Results from an outside laboratory may take a few days; hospital results are often available within hours.
If a value is out of range, your doctor may repeat the panel, add magnesium, calcium or phosphate, order a blood gas test to look more closely at acid-base balance or check urine electrolytes to see whether the kidneys are losing or holding on to minerals. Medicines are adjusted only after the result is confirmed and the cause is understood.
Quando consultare un medico
Seek emergency care if an abnormal electrolyte result comes with confusion, a seizure, fainting, chest pain, palpitations or an irregular heartbeat, severe muscle weakness, trouble breathing or vomiting that will not stop. Cleveland Clinic advises going to the emergency room for extreme muscle weakness, difficulty breathing or chest pain with high potassium. Contact your doctor soon if any of the following applies:
- Potassium below 3 mmol/L or above 5.5 mmol/L on your report.
- Sodium below 135 mmol/L with headache, nausea, unsteadiness or new confusion.
- An abnormal result after starting or changing a diuretic or blood pressure medicine.
- Repeated imbalances alongside kidney, heart or liver disease.
- A low CO2 with fatigue, rapid breathing or nausea.
A single mildly abnormal value with everything else normal and no symptoms is usually rechecked rather than treated.
Ultimi progressi scientifici
Recent research has looked at what pushes electrolytes out of range in daily life and how doctors can keep patients on the medicines they need.
Hot weather lowers sodium
A 2024 systematic review, a study that pools earlier research, gathered 34 studies from 23 countries and found that higher outdoor temperatures were consistently linked to more cases of low sodium. Adults over 65, children, people taking diuretics or antidepressants, people with kidney problems and people exercising hard were the most vulnerable, although most of the studies had limitations. What this means for you: during heat waves, drink sensibly rather than excessively, and ask about a sodium check if you take a water pill and feel unwell.
Very low sodium must be corrected slowly
A 2024 review of 96 published cases of osmotic demyelination, a rare but serious nerve injury in the brain, found that most patients had very low sodium that was raised too quickly on the first day of treatment. The authors support cautious daily targets for people at high risk. What this means for you: if you are treated in hospital for very low sodium, the team raises it gradually on purpose, and frequent blood tests are part of keeping that process safe.
Two common water pills, different electrolyte effects
A 2026 analysis of six studies comparing two widely used thiazide diuretics for high blood pressure, chlorthalidone and hydrochlorothiazide, found similar protection against heart attack and stroke, but more low potassium and low sodium with chlorthalidone. The evidence comes from a small number of studies and needs confirmation. What this means for you: if you take either medicine, regular electrolyte checks matter, and your doctor can weigh the choice against your results.
A diabetes and kidney medicine that helps control potassium
A 2025 Canadian study followed more than 20,000 adults aged 66 and older who were taking blood pressure medicines that can raise potassium and who started an SGLT2 inhibitor, a drug class used for diabetes, heart failure and kidney disease. They had a modestly lower risk of high potassium and were less likely to stop their blood pressure medicine than similar people who did not start one. What this means for you: if high potassium has been a problem, newer treatment combinations may make it easier to stay on protective medicines.
Stopping protective medicines after high potassium carries its own risk
A 2023 study of more than 21,000 people with heart failure or chronic kidney disease in the United States and Japan found that about a third did not refill their blood pressure medicine after an episode of high potassium. Those who stopped or cut their dose had more heart failure emergencies or kidney failure over the next six months than those who continued. What this means for you: never stop a prescribed medicine because of a potassium result without talking to your doctor, who can often adjust treatment instead.
Glossario
| Termine | Definizione |
|---|---|
| Pannello degli elettroliti | A blood test that measures sodium, potassium, chloride and bicarbonate, and sometimes other minerals. |
| Elettroliti | Minerals that carry an electric charge in body fluids and control water balance, nerve and muscle activity. |
| Iponatremia | A blood sodium below the normal range, usually caused by too much water relative to sodium. |
| Ipernatriemia | A blood sodium above the normal range, usually caused by losing more water than salt. |
| Ipokaliemia | A blood potassium below the normal range. |
| Iperkaliemia | A blood potassium above the normal range, which can affect heart rhythm. |
| Bicarbonate (CO2) | The main buffer that keeps blood from becoming too acidic or too alkaline. |
| Acidosis and alkalosis | Too much acid or too much base in the blood. |
| Gap anionico | A value calculated from sodium, chloride and bicarbonate that helps explain the cause of acidosis. |
| Diuretico | A medicine, often called a water pill, that makes the kidneys remove more salt and water. |
Domande frequenti
What is an electrolyte panel in a blood test?
It is a group of tests on one blood sample that measures sodium, potassium, chloride and bicarbonate (CO2). Some laboratories also include calcium, magnesium or phosphate. The panel shows whether your body’s water, mineral and acid-base balance is steady, and it is often part of a basic or comprehensive metabolic panel.
Do I need to fast for an electrolyte panel?
Usually not. Cleveland Clinic says fasting is typically not required unless other tests, such as blood sugar or cholesterol, are drawn at the same time. Drink your normal amount of fluid, avoid smoking just before the test and tell your provider about any medicines, especially diuretics or potassium supplements.
What are the symptoms of an electrolyte imbalance?
MedlinePlus lists nausea and vomiting, confusion, irritability, weakness, an irregular or fast heartbeat, fatigue, headaches, muscle cramps or spasms and numbness or tingling. Many mild imbalances cause no symptoms at all and are found only on a blood test. Severe symptoms such as confusion, seizures or chest pain need emergency care.
What is the difference between an electrolyte panel and a BMP?
An electrolyte panel measures the four main electrolytes. A basic metabolic panel measures the same four plus glucose, calcium, blood urea nitrogen and creatinine, so it also shows blood sugar and kidney function. Doctors choose the electrolyte panel when only fluid and mineral balance needs checking, for example to monitor a diuretic.
Can drinking too much water affect my electrolyte panel?
Yes. Drinking far more water than the kidneys can remove dilutes the blood and lowers sodium. Mayo Clinic notes this happens most often during endurance events such as marathons. Drinking normally before the test gives the most representative result.
What does a high CO2 on an electrolyte panel mean?
A high CO2 means bicarbonate is above the range, which can point to alkalosis. Repeated vomiting, some diuretics, lung disease such as COPD and Cushing’s syndrome are possible causes. Your doctor reads it together with chloride, potassium and your symptoms, and may order a blood gas test.
Fonti
- MedlinePlus, National Library of Medicine — Electrolyte Panel — MedlinePlus Lab Tests, updated 2024 — medlineplus.gov
- Cleveland Clinic — Electrolyte Panel — Health Library, reviewed 2024 — my.clevelandclinic.org
- Mayo Clinic Staff — Hyponatremia: Symptoms and causes — Mayo Clinic, 2025 — mayoclinic.org
- Cleveland Clinic — Hyperkalemia (High Potassium) — Health Library, reviewed 2023 — my.clevelandclinic.org
- Cleveland Clinic — Low Potassium Levels in Your Blood (Hypokalemia) — Health Library, reviewed 2022 — my.clevelandclinic.org
- Cleveland Clinic — Chloride Blood Test — Health Library, reviewed 2024 — my.clevelandclinic.org
- Cleveland Clinic — CO2 Blood Test — Health Library, reviewed 2022 — my.clevelandclinic.org
- Wootton E, Grossmann M, et al. — Dysnatremia in a changing climate: A global systematic review of the association between serum sodium and ambient temperature — Clinical Endocrinology, 2024 — doi.org/10.1111/cen.15052
- Bastos AP, Rocha PN — Osmotic demyelination as a complication of hyponatremia correction: a systematic review — Jornal Brasileiro de Nefrologia, 2024 — doi.org/10.1590/2175-8239-JBN-2022-0114en
- Ashraf T, Chandni F, et al. — Effectiveness of thiazide diuretics in patients with hypertension: a systematic review and meta-analysis — Annals of Medicine and Surgery, 2026 — doi.org/10.1097/MS9.0000000000004668
- Wing S, Ray JG, et al. — SGLT2 Inhibitors and Risk for Hyperkalemia Among Individuals Receiving RAAS Inhibitors — JAMA Internal Medicine, 2025 — doi.org/10.1001/jamainternmed.2025.0686
- Kanda E, Rastogi A, et al. — Clinical impact of suboptimal RAASi therapy following an episode of hyperkalemia — BMC Nephrology, 2023 — doi.org/10.1186/s12882-022-03054-5
Approfondimenti
- Misura quanto è concentrato il tuo sangue leggendo la nostra serum osmolality guide.
- See how your kidneys handle these minerals by reviewing our urine electrolytes guide.
- Check the mineral some labs add to the panel by opening our guida all'esame del calcio totale nel sangue.
- Explore another mineral linked to kidney health by visiting our guida all'esame del sangue per il fosforo.
- Compare your kidney waste products by exploring our BUN/creatinine ratio guide.
Capire i tuoi esami del sangue con BloodSense
An electrolyte panel only makes full sense when sodium, potassium, chloride and CO2 are read together, alongside your kidney results and medicines. BloodSense helps you understand each value in plain language, with the questions worth asking your doctor. It does not make a diagnosis and does not replace your doctor.
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