Electrolyte imbalances are caused by different conditions and medications that intervene with the body’s natural fluid balance.
Sodium
Hyponatremia is considered the most common electrolyte imbalance. It can be caused by the decrease of the circulating blood volume, as seen in congestive heart failure and hepatic cirrhosis. Additionally, disorders leading to high antidiuretic hormone (ADH) levels, like syndrome of inappropriate ADH secretion (SIADH), adrenal insufficiency, and hypothyroidism can also cause hyponatremia. Primary polydipsia (i.e., excessive water intake), low dietary sodium intake causing an increase in blood volume, hyperglycemia, and dyslipidemia are all causes of hyponatremia. Hypernatremia, on the other hand, is usually caused by unreplaced fluid loss through the skin and gastrointestinal (GI) tract (e.g., excessive sweating, vomiting, or diarrhea), overload of hypertonic saline, medications (e.g. lithium), and rarely, following excessive physical activity that causes water to shift into cells.
Potassium
Hypokalemia is usually caused by low dietary intake or unreplaced fluid loss from the GI tract and urine and can be seen after excessive vomiting and loop diuretic use, respectively. Hyperkalemia can be noted in metabolic acidosis states - this is due to extensive potassium release from cells - but can also be noted in insulin deficiency, diabetic ketoacidosis, beta-blocker use, or following cell death in chemotherapy, where intracellular stores are released. Decreased potassium excretion from the kidneys (e.g. in acute or chronic kidney disease), aldosterone deficiency, or aldosterone resistance can also cause increased potassium levels.
Chloride
Hypochloremia is mostly encountered after great GI fluid losses, as well as in renal fluid losses with diuretics. Hyperchloremia can occur when fluid losses exceed chloride losses; when the body’s ability to manage excessive chloride is disrupted; or when the bicarbonate serum levels are low and chloride levels are high. Normal anion gap metabolic acidosis or respiratory alkalosis may be present with low bicarbonate levels and hyperchloremia.
Bicarbonates
Bicarbonate levels shift in acid-base disturbances. There is an increase in bicarbonate levels in primary metabolic alkalosis and it acts as compensation in primary respiratory acidosis. Bicarbonate falls in both primary metabolic acidosis and also decreases in response to primary respiratory alkalosis.
Calcium
Hypocalcemia can be caused by hypoparathyroidism, typically seen post-surgery after thyroidectomy (i.e., after thyroid removal) due to frequent accidental damage due to their proximity to the thyroid. Hypocalcemia can also be noted in severe vitamin D deficiency, due to malnutrition or malabsorption. Hypercalcemia can be seen in individuals with malignancies, hyperparathyroidism, or in those prescribed thiazide diuretics or lithium.
Magnesium
Hypomagnesemia can be seen after renal or GI fluid losses, and more rarely in individuals who consume excessive amounts of alcohol. Hypermagnesemia can occur after increased magnesium intake, either orally (e.g., after use of magnesium-containing medications such as antacids and laxatives) or more commonly through intravenous access.
Phosphate
Low levels of phosphate in the blood can be seen in individuals with vitamin D deficiency, hyperparathyroidism, and refeeding syndrome, which is a potentially fatal condition that causes unexpected shifts of fluids and electrolytes in
malnourished individuals following re-introduction of food.
Hyperphosphatemia, on the other hand, can be caused by hypoparathyroidism and chronic kidney disease.
