Electrolytes are chemical elements that carry a positive or negative electrical charge. In the human body, the main electrolytes are sodium (Na+), potassium (K+) and chloride ion (Cl-), to which the bicarbonate ion (HCO3- or CO2) is sometimes added. Other elements such as calcium, magnesium or phosphate ion are also electrically charged but are not part of the basic electrolyte panel. In total, the body’s fluids contain an equal number of negative and positive charges. Electrolytes play a vital role in the human body: sodium is responsible for the amount of water retained in the body, and an imbalance can lead to edema or dehydration. Potassium, the main intracellular electrolyte, is involved in the transmission of nerve impulses and muscle contractions, among others. Potassium, bicarbonate and chloride ions are involved in maintaining the blood’s pH level, and disorders in these electrolytes can lead to acidosis or alkalosis. All these elements are in equilibrium with each other, enter and leave cells as needed, and depend on dietary intake and losses in the urine, stools, exhaled air and sweat. What’s more, their levels are affected by many medications (e.g., diuretics and anti-hypertensives) as well as the involvement of several control systems (e.g., adrenal glands, kidneys, digestive tract, pituitary gland, antidiuretic hormone, etc.).