Common Electrolyte Abnormalities Cheat Sheet

Electrolyte abnormalities are common in emergency medicine and can vary greatly in importance, severity, and symptoms. Asymptomatic electrolyte abnormalities can usually be gradually corrected, but those that cause alterations in consciousness or lifethreatening dysrhythmias require immediate therapy to avoid permanent sequelae or death. In some cases, therapy for lifethreatening electrolyte disorders may even need to be initiated before laboratory results become available.

Most Common Electrolyte abnormalities are include:


Hyperkalemia, defined as serum potassium level greater than 5.0 mEq/L, is the most dangerous acute electrolyte abnormality, potentially leading to life-threatening arrhythmias and death. Although hyperkalemia may have vague and varied symptoms, it is usually totally asymptomatic, with cardiac arrest as its first “symptom”.

Causes of Hyperkalemia:

• Decreased renal excretion related to oliguric renal failure, potassium-sparing diuretic use, or adrenal steroid deficiency
• High potassium intake related to the improper use of oral supplements, excessive use of salt substitutes, or rapid infusion of potassium solutions
• Acidosis, tissue damage, or malignant cell lysis after chemotherapy

Signs & Symptoms:

• Potassium level above 5 mEq/L
• Cardiac conduction disturbances, ventricular arrhythmias, prolonged depolarization, decreased strength of contraction, and cardiac arrest
• Tall, tented T wave; prolonged QRS complex and PR interval on ECG
• Muscle weakness and paralysis
• Nausea, vomiting, diarrhea, intestinal colic, uremic enteritis, decreased bowel sounds, abdominal distention, and paralytic ileus


Hypokalemia is the most common electrolyte abnormality encountered in clinical practice. When it is defined as a value of less than 3.5 mEq/L, hypokalemia is found in more than 20% of hospitalized patients and in 10 to 40% of patients treated with thiazide diuretics in the outpatient setting.19 Although hypokalemia is usually asymptomatic, severe cardiac dysrhythmias and rhabdomyolysis can occur secondary to potassium’s effect on the heart and muscle.

Most common Causes of Hypolalemia include the following:

• GI losses from diarrhea, laxative abuse, prolonged gastric suctioning, prolonged vomiting, ileostomy, or colostomy
• Renal losses related to diuretic use, renal tubular acidosis, renal stenosis, or hyperaldosteronism
• Use of certain antibiotics, including penicillin G sodium, carbenicillin, or amphotericin B (Abelcet)
• Steroid therapy
• Severe perspiration
• Hyperalimentation, alkalosis, or excessive blood insulin levels
• Poor nutrition


Hypernatremia is defined as a serum sodium concentration above 145 mEq/ L and is usually associated with a poor prognosis. It is uncommon in previously normal patients, and in adults it is almost exclusively due to a total body water deficit.32 Most hypernatremic patients have either an impaired sense of thirst or no access to water.

Causes of Hypernatremia:

• Sodium gain that exceeds water gain related to salt intoxication (resulting from sodium bicarbonate use in cardiac arrest), hyperaldosteronism, or use of diuretics, vasopressin, corticosteroids, or some antihypertensives
• Water loss that exceeds sodium loss related to profuse sweating, diarrhea, polyuria resulting from diabetes insipidus or diabetes mellitus, high-protein tube feedings, inadequate water intake, or insensible water loss.


Hyponatremia, defined as serum sodium concentration of less than 135 mEq/L, is the second most common electrolyte abnormality encountered in clinical practice.37 It is important to recognize hyponatremia because of its potential morbidity and also because it can be a marker of underlying disease.

Causes of Hyponatremia:

• Excessive water gain causedby inappropriate administration of I.V. solutions, syndrome of inappropriate antidiuretic hormone, oxytocin use for labor induction, water intoxication, heart failure, renal failure, or cirrhosis.
• Excessive sodium loss due to GI losses, excessive sweating, diuretic use, adrenal insufficiency, burns, lithium (Lithobid) use, or starvation

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