Electrolytes

Electrolytes are minerals that are dissolved in the body’s fluids, water, and blood stream. They have either positive or negative electric charges and help regulate the function of every organ in the body. An electrolyte panel blood test usually measures sodium, potassium, chloride, and bicarbonate. BUN (blood urea nitrogen) and creatinine may also be included to measure kidney function.

Definition of electrolytes

Electrolytes are minerals that are dissolved in the body’s fluids, water, and blood stream. They have either positive or negative electric charges and help regulate the function of every organ in the body including the heart, muscles, bones, nerves, and brain. Electrolytes maintain the acid-base balance in the body to help it function optimally and help move nutrients from the blood stream into cells, and remove metabolism waste products from those cells.

Since electrolytes are found in the body’s fluids, they are also present in sweat and urine. There is normal loss of electrolytes and they have to be replaced by eating and drinking.

A variety of hormones help the kidneys regulate electrolyte concentrations in the body.

Serum in the bloodstream is what is left after the red blood cells, white blood cells, and clotting factors are removed. Much of serum is water and it contains the bloodstream’s electrolytes. Some electrolytes are concentrated in an organ’s cell, while others are concentrated in the serum.

Electrolytes move in and out of cells temporarily and this helps the cells function normally. This includes conducting electricity in muscle including the heart muscle, having brain and nerve function, and allowing calcium to enter and exit bone. The concentration of electrolytes also helps regulate the amount of water in the body.

The electrolytes in the body are either positively charged or negatively charged. The body’s acid-base balance depends on the proper concentration of electrolytes and allows the organs in the body to function normally. A pH of 7.4 is a normal measurement of the acid-base balance. The body depends on a normal acid-base balance to function normally.

Diseases that alter that balance can cause the body to fail. For example, patients with poorly-controlled diabetes can develop ketoacidosis, lowering the serum pH. Patients who outstrip the body’s ability to get energy from aerobic (using oxygen) metabolism, can become anaerobic, like in excessive exercise, and develop lactic acidosis.

Positively charged electrolytes or cations:

• Sodium (Na⁺)
• Potassium (K⁺)
• Calcium (Ca⁺)
• Magnesium (Mg⁺)

Negatively charged electrolytes or anions:

• Bicarbonate (HCO₃)
• Chloride (Cl^-)
• Phosphate (PO₄)

Sodium

Sodium (Na⁺) is a major positive ion (cation) mostly located in serum. In association with potassium (K⁺) ions located inside cells, the Na-K pump helps stabilize cell membranes to keep cells intact and functioning.

When sodium levels get too low, the regulatory systems in the body see it as having too much water in the serum causing the sodium to become diluted. The attempted fix is to move water into cells, potentially causing them to swell. This is especially dangerous if brain cells start swelling.

Potassium

Potassium (K⁺) is a major positive ion (cation) found inside of cells. K⁺ is important in regulating electrical conduction especially in the heartbeat and muscle. An abnormal level of potassium in the bloodstream, either high or low, can affect the nervous system function (brain, spinal cord, peripheral nerves), and increases the potential for abnormal heart rhythms.

Chloride

Chloride (Cl^-) is a major anion found in the serum outside of cells and in the blood. Cl^- plays a role in helping the body maintain a normal acid-base balance of fluids.

The balance of the chloride ion is closely regulated by the body. Significant changes in chloride concentrations can affect body function. Often chloride is lost because of excessive vomiting, the use of diuretic medications, or kidney failure.

Bicarbonate

The bicarbonate ion (HCO₃) acts as a buffer to maintain the normal levels of acidity (pH) in blood and other fluids in the body. HCO₃ may be a reflection of kidney and lung function.

Calcium, Magnesium, Phosphorus

Calcium, magnesium, and phosphorus are important in nerve and muscle function.

Ca⁺ is stored in bone, but bone is not stagnant. There is constant turnover of bone cells to make certain that serum calcium levels remain normal. Parathyroid hormone and calcitonin are two hormones that regulate calcium levels in the body.

Ca⁺ and Mg⁺ are dependent upon each other for absorption from the intestine and excretion in the urine. Both need to be present to allow normal body function.

PO₄ is mostly stored in bones and teeth and is involved in the use of carbohydrates and fats in cells for energy and cell repair. PO₄ works closely in the body with calcium.

An electrolyte panel blood test usually measures Na⁺, K⁺, Cl^- and HCO₃. BUN (blood urea nitrogen) and creatinine may also be included to measure kidney function.

What are normal levels for electrolytes?

Blood tests measure serum concentrations (these are usual ranges but can be slightly different depending on the laboratory performing the test):

• Sodium: 136 to 144 mmol/L
• Potassium: 3.7 to 5.1 mmol/L
• Chloride: 97 to 105 mmol/L
• Bicarbonate: 22 to 30 mmol/L

Anion Gap measures the difference between the major positive (Na⁺, K⁺) and major negative ions (Cl^-, HCO₃) in the body. A normal anion gap is 4-12 mmol/L.

If the anion gap is elevated, unmeasured negative ions are present in the body. This calculation can be a clue in diagnosing a variety of illnesses and in combination with the pH measurement, can determine how ill a patient might be. Examples of unmeasured anions might be ketones in poorly controlled diabetes, lactic acid from anaerobic metabolism, or salicylic acid from aspirin ingestion.

The following are not part of routine electrolyte blood tests and need to be ordered separately if the health care provider needs this information:

• Calcium: 8.5 to 10.2 mg/dL (in adults)
• Magnesium: 1.7 to 2.2 mg/L
• Phosphorus: 2.5 to 4.8 mg/L

What happens when electrolytes are low or high?

Sodium

• Increased sodium (hypernatremia: hyper=more + natr=sodium + emia=blood) occurs when there is excess sodium in relation to water. It is most often associated with dehydration. Some causes include dehydration from vomiting or diarrhea, poor water intake, excess sweating, or kidney disease. Symptoms may include weakness, lethargy, confusion, and muscle twitching and spasm.
• Decreased sodium (hyponatremia: hypo=less) occurs whenever there is an increase in the amount of body water relative to sodium. This may happen with diseases of the heart, liver and kidney, some medications, illegal drugs like ecstasy, and excessive water intake. Symptoms may include altered mental status ranging from lethargy and confusion to seizure and coma. Other symptoms may include headache, fatigue, nausea and vomiting, and muscle spasm.

Potassium

• Increased potassium (hyperkalemia: hyper=more + kal=potassium + emia=blood). Potassium is normally excreted by the kidneys, so disorders that decrease the function of the kidneys can result in hyperkalemia. Some medications like spironolactone (a diuretic) may cause elevated potassium levels. The major risk of hyperkalemia is to the heart’s conduction system and can lead to lethal heart rhythms like ventricular tachycardia or ventricular fibrillation.
• Decreased potassium (hypokalemia: hypo=less) often is caused by excessive losses due to vomiting, diarrhea, eating disorders, and certain medications including diuretics such as furosemide and hydrochlorothiazide.

Chloride and Bicarbonate

Abnormal levels of chloride and bicarbonate are usually associated with abnormalities of sodium and potassium.

The best source of electrolytes for the body is a well-balanced diet.

The body is capable of maintaining normal levels of electrolytes during most routine daily activities. The hormone system and the kidneys are on duty 24 hours a day to maintain normal electrolyte balance, especially when you keep the body well hydrated.

Plain water is probably adequate to keep the body well-hydrated, unless there is prolonged exercise and sweating (more than an hour) or if exposed to excessive heat.

There are many electrolyte supplements available for purchase. It is important to read the label to know what each contains, and whether there is an abundance of sugar as part of a drink supplement.

If using a powder, it is important to mix it properly so that the electrolyte supplements are not too concentrated.

Patients with heart or kidney disease should consult with their health care provider before using any supplement.