An electrolyte panel is a group of blood tests that measure electrolyte levels to assess the general functioning of the patient’s organ systems. Electrolytes are naturally occurring minerals in the body that carry an electrical charge. They help regulate a number of important bodily functions (e.g., fluid levels, heartbeat). Electrolytes that are commonly measured include calcium, potassium, chloride and sodium, although there are many others. The results of an electrolyte panel can help a physician make a diagnosis or monitor the progress of treatment with medications.


Abnormal electrolyte levels may be caused by several conditions, including many digestive system conditions. For example, the loss of fluids and salts caused by vomiting, diarrhea or gastrointestinal bleeding can reduce electrolyte levels. In other cases, an electrolyte condition can trigger problems in the digestive system. For instance, low levels of electrolytes can cause a person to become constipated.

Electrolyte tests are typically performed in a physician’s office or directly at the lab. Patients should follow physician’s restrictions on diet, exercise and medication use prior to having an electrolyte panel. Use of many types of medications – including antibiotics, antacids and laxatives – may affect results.

A blood sample is used to measure a patient’s electrolyte levels. The blood is usually drawn from a vein (venipuncture) from the inside of the elbow or the back of the hand. After the blood is collected, the needle is withdrawn and a small cotton ball or pad is applied with light pressure over the puncture site. Despite the precautions taken to avoid bruising and soreness, it does sometimes occur.

Once the sample has been obtained it is analyzed in a laboratory. An appropriate treatment will follow based on information revealed from the test if necessary. Electrolyte testing may also be used to monitor the progress of treatment. For this purpose, regular testing may be required.

An electrolyte panel is a group of blood tests that measures electrolyte levels to assess the general functioning of the patient’s organ systems. Electrolytes, minerals that carry an electrical charge, are found throughout the body in varying concentrations. They move between locations to restore balance when needed and regulate a number of functions, including fluid levels, heart rhythm and muscle contraction. Testing electrolyte levels in the blood can therefore provide physicians with valuable information about what chemical imbalances are occurring in the body.

Electrolytes include calcium, potassium, chloride and sodium, in addition to many others. Carbon dioxide, a waste product, is also frequently measured during an electrolyte panel. When dissolved in a solution such as blood, electrolyte molecules split into ions (electrically charged particles) that allow the solution to conduct electricity. Because they are electrical conductors, electrolytes play an important role in many body processes, such as controlling fluid levels, acid-base balance, nerve conduction, blood clotting and muscle contraction.

Electrolyte imbalance can be caused by a number of conditions, including many associated with the digestive system. For example, the loss of fluids and salts caused by diarrhea or vomiting can reduce electrolyte levels. Other digestive conditions that may cause an electrolyte imbalance include liver disorders, gastrointestinal bleeding, gastroparesis and Whipple's disease.

In some cases, the electrolyte condition may trigger the digestive system condition, rather than the other way around. For example, low levels of electrolytes can cause a person to become constipated. 

Electrolyte imbalances can result in serious problems such as dehydration, fever, nausea and vomiting and in some cases even death. In addition to digestive disorders, kidney failure, heart disease and disorders of the endocrine system (glands) all can lead to long-term electrolyte imbalances.

An electrolyte panel can help a physician to monitor the body’s electrolyte balance. If abnormal levels are found, treatments such as fluid replacement can help restore the body’s electrolytes and prevent serious health consequences.

Not only is electrolyte testing performed as part of a basic evaluation and diagnosis, but it may also be used to monitor the progress of treatment because many medications will affect electrolyte balances within the body. For this purpose, regular testing may be required.

An electrolyte panel typically includes blood levels of the following electrolytes:

• Calcium. More than 98 percent of the body’s calcium is stored inside bones and teeth. Calcium is necessary for bone health, coagulation (blood clotting), and maintaining adequate heartbeat and proper pH balance. Calcium levels are used to diagnose disorders of the parathyroid glands, which regulate calcium absorption in the blood. Pregnant women and older people often have low levels of calcium, and frequently take calcium supplements to prevent bone loss. Otherwise, low calcium levels in the blood (hypocalcemia) could cause calcium ions to move from bones and teeth into the blood, weakening the bones and teeth as blood calcium levels are restored. Digestive disorders such as pancreatitis can contribute to low calcium levels. Medications used to treat inflammatory bowel disease (corticosteroids) can also contribute to low calcium levels.
  
  High levels of calcium in the blood (hypercalcemia), most commonly caused by parathyroid overactivity or by cancer, can damage the kidneys and bones, and impair functions of the central nervous system, stomach and other organs.  However, calcium levels in the blood cannot be used to determine if patients are getting enough calcium from their diet or if calcium is being lost from the bones (as part of osteoporosis).
  
  
• Phosphates. Phosphorous exists mostly in bones and teeth (about 80 percent). It generally has an inverse relationship with calcium, such that it decreases as calcium increases and vice versa. Low phosphorus levels usually cause muscle weakness. Patients in intensive care on ventilators are especially prone to develop low phosphorus levels.  Very few conditions will affect phosphorous levels in the blood, so testing for phosphorous alone is not usually very helpful. However, in combination with calcium blood testing, phosphorous testing can be a valuable diagnostic tool.
  
  
• Sodium. Sodium is a vital electrolyte in the fluids that carries nutrients to cells and helps regulate blood pressure. Sodium levels can directly influence potassium and chloride levels in the body. Because of this, sodium levels are a good indicator of overall electrolyte balance. Sodium is a component of table salt (sodium chloride) and most people consume far more sodium each day than their bodies need. Over time, too much sodium may lead to an increase in blood pressure, which, in turn, increases the risk of kidney failure,  stroke and heart disease. Low sodium levels may indicate disorders such as liver failure, diabetes and syndrome of inappropriate anti diuretic hormone secretion (SIADH; condition that causes water retention and decline in certain electrolyte levels).
  
  
• Chloride. Chloride helps to regulate blood pressure and volume by balancing its negative charge with the positive charge of sodium. Chloride levels in the blood are used to evaluate the body’s pH balance and fluid levels. As with sodium, most people ingest more chloride through table salt than their bodies require. Heart failure and water retention can cause low chloride levels (hypochloremia). High levels of chloride (hyperchloremia) may indicate severe dehydration, kidney dysfunction or other conditions. Chloride levels generally increase as sodium levels increase and vice versa. They react inversely with bicarbonate, increasing as bicarbonate decreases and vice versa.
  
  
• Potassium. Potassium regulates many of the body’s organ functions and basic physiology. Blood potassium levels become high (hyperkalemia) following muscle damage because excess amounts are released into the blood, or from kidney failure or acidosis. Low potassium levels (hypokalemia) – which may be caused by prolonged diarrhea or vomiting – can lead to abnormal heart rhythms, respiratory paralysis or cardiac arrest.
  
  
• Magnesium. Magnesium is important for healthy nerve function and muscle contraction. Magnesium testing is used to evaluate electrolyte imbalance and to assess nerve and muscle functions. Low magnesium levels can cause arrhythmias (irregular heart rhythms), muscle weakness or cramps, seizures and other problems. High magnesium levels are usually an indicator of kidney failure.
  
  
• Bicarbonate. Bicarbonate is a form of carbon dioxide (CO2) found in the blood and is a byproduct of metabolism. When the amount of CO2 in the red blood cells is too high, the gas spills out of the cells into the plasma (the liquid part of blood). Once in plasma, CO2 may join with water to produce carbonic acid (bicarbonate). Therefore, bicarbonate levels are an indirect measurement of the amount of CO2 in the bloodstream.
  
  High levels of CO2 may indicate a disease that decreases blood pH (respiratory acidosis), such as chronic obstructive pulmonary disease (COPD) and pneumonia. Or, they may indicate a disease that increases blood pH (metabolic alkalosis), such as Cushing syndrome or Conn's syndrome (both adrenal gland malfunctions) or severe vomiting. The results of these tests can be skewed by using drugs such as corticosteroids, diuretics, barbiturates or high doses of steroid hormones. Test results may also indicate higher than actual levels in the body if the person consumed an excessive amount of antacids or black licorice prior to testing.
  
  Low CO2 levels may indicate metabolic problems that decrease blood pH (metabolic acidosis), such as uncontrolled diabetes, kidney or heart failure, aspirin overdose, shock or ingesting methyl alcohol (anti-freeze or wood alcohol). They may also indicate a disease that increases blood pH (respiratory alkalosis), such as asthma, pneumonia, liver disease and severe anxiety. Using aspirin or certain types of antibiotics can skew tests results.

Patients should follow the physician’s restrictions on diet, exercise and medication use prior to the test. The test is performed in a physician’s office for laboratory analysis or directly at the lab. Blood is usually drawn from a vein (venipuncture) from the inside of the elbow or the back of the hand. First the puncture site is sterilized with antiseptic and an elastic band is wrapped tightly around the patient’s upper arm. The pressure created by the band restricts blood flow through the vein and causes the veins below the band to fill with blood.

A needle is then inserted into a vein. Occasionally more than one puncture is necessary to locate a vein. Some people may feel slight pain when the needle is inserted, but most only feel a prick or stinging sensation. Once the needle is inserted into a vein, a tube is attached to collect the blood as it begins to flow out. The elastic band is then removed.

After the necessary amount of blood is collected, the needle is withdrawn and a small cotton ball or pad is applied with light pressure over the puncture site. After several minutes, the cotton will be discarded or replaced, and a small bandage will be placed on the puncture wound. The entire process takes less than 10 minutes. The sample is sent to a laboratory for analysis, and results are returned in several days.

Despite the precautions taken to avoid bruising and soreness, it does sometimes occur. Typically, this is not a cause for great concern. To minimize soreness, patients may immediately apply a warm compress to the puncture site and repeat the application every three hours until the discoloration or pain subsides.

Many factors may affect electrolyte panel results. Many electrolyte tests require patients to refrain from eating for six to 12 hours prior to testing. Patients should follow their physician’s restrictions on diet, exercise and medication use prior to the test. Medications can affect blood electrolyte levels, and electrolyte testing is often performed to monitor the doses of medication and prevent side effects. Medications that may affect blood electrolyte levels include:

• Antidiabetic agents. Medications used to treat type 2 diabetes by decreasing the amount of glucose (blood sugar) circulating in the blood.
  
  
• Insulin. All people with type 1 diabetes and some people with type 2 diabetes take insulin by injection, pump or other means to regulate glucose levels.
  
  
• Diuretics. Medications that promote the formation of urine in the kidneys, causing the body to flush out fluids and minerals through the urine.
  
  
• Antibiotics. Medications that harm or kill microorganisms and are commonly used to treat bacterial infections.
  
  
• Oral contraceptives (birth control pills). Medications that regulate the reproductive cycle of women and prevent pregnancy.
  
  
• Anabolic steroids. Synthetic hormones used to stimulate metabolism and muscle growth.
  
  
• Corticosteroids. Synthetic hormones used to reduce inflammation.
  
  
• Anticonvulsants. Medications to treat convulsions and seizures.
  
  
• Androgens. Hormones naturally found in the body that are used in the treatment of some breast cancers in females and late puberty or other conditions in males.
  
  
• Estrogen. Female hormone naturally found in the body. A synthetic form of this hormone is used as part of hormone replacement therapy.
  
  
• Antidepressants (long-term use). Medications used primarily to treat clinical depression and other mood disorders.
  
  
• Nonsteroidal anti-inflammatory drugs (NSAIDs). Medications that reduce pain and inflammation by inhibiting the production of certain chemicals in the body. Aspirin is a common NSAID that is typically used as a pain reliever (analgesic) but also reduces inflammation and inhibits the formation of blood clots (anticoagulant).
  
  
• Vitamin D supplements (long-term use).
  
  
• Antacids containing calcium.
  
  
• Antiseptic acids. Substances, usually applied to the skin, which inhibit the growth of microorganisms such as bacteria.
  
  
• Medications to treat glaucoma (an eye disorder).
  
  
• Cough medicines.
  
  
• Calcium salts.
  
  
• Laxatives (long-term use).

Electrolyte tests are measured in milligrams per deciliter (mg/dl) or milliequivalents per liter (mEq/L). Normal blood levels are as follows:

• Calcium: 8.5 to 10.5 mg/dl. Levels in children can be as high as 12 mg/dl because their bones are still growing.
  
  
• Phosphorous: 2.4 to 4.1 mg/dl. Levels in children can be as high as 7 mg/dl.
  
  
• Sodium: 136 to 144 mEq/L.
  
  
• Chloride: 101 to 111 mEq/L.
  
  
• Potassium: 3.7 to 5.2 mEq/L.
  
  
• Bicarbonate (and carbon dioxide): 22 to 34 mEq/L.
  
  
• Magnesium: 1.5 to 2.5 mEq/L.
  
  
• Ammonia: 10 to 40 moles/L.

Abnormal electrolyte levels may indicate or result in the following digestive system disorders:

• Diarrhea. An increase in the liquidity or volume of stool or the frequency of bowel movements.
  
  
• Vomiting. The forceful expulsion of stomach contents through the mouth.
  
  
• Liver disorders. Disorders that affect the liver, one of the body’s largest and most vital organs.
  
  
• Gastrointestinal bleeding. Any type of blood loss that originates in the gastrointestinal (GI) tract, from the mouth to the anus.
  
  
• Gastroparesis. A condition in which food or liquid passes too slowly from the stomach into the small intestine.
  
  
• Constipation. The painful or difficult passing of food product waste (stool) through the anus.
  
  
• Whipple's disease. A rare disease that is caused by bacteria.
  
  
• Malnutrition. Inadequate nutrition that may be caused by an unbalanced diet or malabsorption, a condition in which the body has difficulty digesting or absorbing nutrients from food.

Other conditions that may be associated with abnormal electrolyte levels include:

• Severe dehydration. Not enough fluids in the body. Diabetic ketoacidosis and hyperosmolar hyperglycemic nonketotic syndrome are two complications of diabetes that are strongly linked to dehydration.
  
  
• Bone or lung disease.
  
  
• Diabetes. A metabolic condition in which glucose (blood sugar) levels are too high because of either a lack of, or inability to use, the hormone insulin.
  
  
• Kidney failure or kidney disease.
  
  
• Heart attack (or myocardial infarction). A heart attack is an event that results in permanent heart damage or death.
  
  
• Heart failure. A serious condition in which the heart is not pumping well enough to meet the body’s demand for oxygen.
  
  
• Arrhythmias. Abnormal heart rhythms resulting from an abnormal deviation or malfunction in the heart’s electrical system.
  
  
• Endocrine disorders. Electrolytes are controlled by various glands within the body. Improper levels of a specific electrolyte in the blood could be an indication that the gland that produces the electrolyte is not functioning properly.
  
  
• Tissue trauma.
  
  
• Hemolysis (dissolving of red blood cells).

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to electrolyte panels:

1. Why are you recommending that I undergo an electrolyte panel test?
   
   
2. How might abnormal electrolyte levels impact my health?
   
   
3. For which electrolytes do you plan to test?
   
   
4. Where will my test be performed?
   
   
5. How should I prepare for the test?
   
   
6. How long will my test last?
   
   
7. How long will I have to wait before I receive my test results?
   
   
8. Which factors could skew my test results?
   
   
9. What treatments might follow if my results indicate an electrolyte imbalance?
   
   
10. Will I have to undergo future electrolyte panels?