Electrolytes play a vital role in maintaining homeostasis within the body. They help to regulate myocardial and neurological function, fluid balance, oxygen delivery, acid-base balance and much more. Electrolyte imbalances can develop by the following mechanisms: excessive ingestion; diminished elimination of an electrolyte; diminished ingestion or excessive elimination of an electrolyte. The most common cause of electrolyte disturbances is renal failure.
The most serious electrolyte disturbances involve abnormalities in the levels of sodium, potassium, and/or calcium. Other electrolyte imbalances are less common, and often occur in conjunction with major electrolyte changes. Chronic laxative abuse or severe diarrhea or vomiting can lead to electrolyte disturbances along with dehydration. People suffering from bulimia or anorexia are at especially high risk for an electrolyte imbalance.
There is a standard nomenclature for electrolyte disorders:
The name starts with a prefix denoting whether the electrolyte is abnormally elevated ("hyper-") or depleted ("hypo-").
The word stem then gives the name of the electrolyte in Latin. If no Latin equivalent exists, then the corresponding term in English is used.
The name ends with the suffix "-emia," meaning "in the blood." (Note, this doesn't mean that the disturbance is only in the blood; usually, electrolyte disturbance is systemic. However, since the disturbance is usually detected from blood testing, the convention has developed.)
For instance, elevated potassium in the blood is called "hyperkalemia" from the Latin term for potassium, "kalium".
Electrolytes are important because they are what your cells (especially nerve, heart, muscle) use to maintain voltages across their cell membranes and to carry electrical impulses (nerve impulses, muscle contractions) across themselves and to other cells. Your kidneys work to keep the electrolyte concentrations in your blood constant despite changes in your body. For example, when you exercise heavily, you lose electrolytes in your sweat, particularly sodium and potassium. These electrolytes must be replaced to keep the electrolyte concentrations of your body fluids constant.
Electrolyte Abnormalities and ECG Changes
The most notable feature of hyperkalemia is the "tent shaped" or "peaked" T wave. Delayed ventricular depolarization leads to a widened QRS complex and the P wave becomes wider and flatter. When hyperkalemia becomes severe, the ECG resembles a sine wave as the P wave disappears from view. In contrast, hypokalemia is associated with flattenting of the T wave and the appearance of a U wave. When untreated, hypokalemia may lead to severe arrhythmias.
The fast ventricular depolarization and repolarization associated with hypercalcemia lead to a characteristic shortening of the QT interval. Hypocalcemia has the opposite effect, lengthening the QT interval.