Electrolyte imbalances
HYPONATREMIA -less than 135
Hyponatremia is diagnosed when the serum sodium concentration is less than
135mEq/L.
HYPOVOLEMIC HYPONATREMIA
Water volume decreases slightly or remains relatively stable, but sodium depletes due
to other modalities.
Causes
● Salt-wasting diuretics
● Gastrointestinal (GI) fluid loss (vomiting, diarrhea, suctioning)
● Profuse diaphoresis
HYPERVOLEMIC HYPONATREMIA
Water volume increases while sodium intake is stable, leading to a decreased level of
sodium in the blood plasma.
Causes
● Water intoxication or excessive fluid intake
● Prolonged use of hypotonic intravenous (IV) solutions
● Syndrome of Inappropriate Anti-diuretic Hormone (SIADH)
HYPERNATREMIA- more than 145
Increased serum sodium in the blood plasma
Sodium Excess hypernatremia
● Excessive sodium intake
● Hypertonic IV solutions
● Hypertonic enteral feedings without adequate water
Water Depletion hypernatremia
● Diarrhea and/or vomiting (emesis)
● Inadequate intake of water or dehydration
● Insensible loss of water due to fever (hyperthermia)
HYPOKALEMIA- less than 3.5
Causes: nausea, vomiting, gastric suctioning, laxative abuse, or frequent enemas,
inadequate intake caused by alcoholism or anorexia, loop diuretics, NPO status, IV fluids
with no supplemental k+, corticosteroids and chemotherapeutics
Diseases such as hyperaldosteronism and hypOmagnesemia can lower K+.
HYPERKALEMIA- more than 5
Causes: impaired renal excretion, excessive intake of K+, cushing syndrome, potassium
sparing diuretics (spiralactone), tissue damage from trauma or burns, severe infections
causing the release of intracellular potassium, excessive or rapid infusion of iv fluids
containing potassium, medications the reduce aldosterone effects like aldosterone
blockers, ace inhibitors.
HYPOCALCEMIA- less than 9.0
Causes: inadequate intake of calcium and vitamin D, inability to absorb calcium due to
caffeine, antibiotics or phosphates, chronic kidney disease causing a deficiency in
activated vit D, pancreatitis, malabsorption syndromes, plasma protein depletion caused
by malnutrition, increase in unbound calcium making kidneys excrete more calcium,
chronic diarrhea, laxative abuse.
Can also be caused by other electrolyte imbalances such as;
Hypomagnesemia
Altered passive reabsorption of magnesium (magnesium plays a role in calcium
reabsorption)
Hyperphosphatemia
Precipitate calcium in the tissues, causing decreased plasma calcium levels
Hypoparathyroidism
Surgery of the head and neck, which alters the secretion of parathyroid hormone
HYPERCALCEMIA- greater than 10.5
The most common cause is overproduction of parathyroid hormone
Other causes: extended periods of immobility, malignancy especially lung or breast
cancer, excessive intake of vit D, excessive dietary calcium, diseases that cause excessive
vit D production, family history of hypocalciuric hypercalcemia.
HYPOMAGNESEMIA- less than 1.3, not usually symptomatic until level is below
1.0
The most common cause; decreased intake or absorption, and increased excretion or loss
Decreased Intake or Absorption
● Total parenteral nutrition (TPN) without magnesium replacement
● IV fluids without magnesium replacement
increased Excretion or Loss
● GI suctioning
● Diarrhea
● Laxative abuse
● Ulcerative colitis
● Crohn’s disease
● Increased renal secretion
● Diabetic ketoacidosis
● Hyperaldosteronism related to liver disease
Causes: hypomagnesemia often occurs along with hypokalemia and hypocalcemia,
Drug administration
Loop and thiazide diuretics, which do not allow for conservation of magnesium,
Nutritional deficits, Alcoholism, Low dietary intake of phosphate
HYPERMAGNESEMIA- more than 2.1
Two distinct causes; kidney failure,mag is not properly excreted from the body.
Excessive intake, antacids containing magnesium, TPN with added magnesium, IV
infusions as seen in pregnant women with pre-eclampsia, and abuse of laxatives or
enemas that contain magnesium.
Other causes; adrenal insufficiency, leukemia.
HYPOPHOSPHATEMIA- lower than 1.7
Causes; abnormal shift of phosphate into the cell, this can be caused by hyperventilation,
respiratory alkalosis, hyperglycemia, and hypercalcemia. Decreased absorption phosphate
from GI, antacids, starvation, alcoholism, malabsorption syndromes, inadequate vitamin
D intake, chronic diarrhea, and cathartic or laxative abuse. Increased excretion by the
kidneys, hiazides and loop diuretics, diuresis from diabetic ketoacidosis, or an increased
parathyroid hormone (PTH) secretion.
HYPERPHOSPHATEMIA- higher than 2.6
Renal Excretion
As the glomerular filtration rate decreases, the excretion of excess phosphate diminishes
and the plasma level increases.
Excessive Intake
Excessive intake is often related to oral or intravenous phosphate administration and
overuse of phosphate-containing cathartics.
Acid-Base Disturbances
Acidosis may break apart phosphate-containing compounds, thus releasing the phosphate
into the extracellular fluid.
Injury
Cellular injury resulting from tumor lysis syndrome, crush injury, or rhabdomyolysis all
cause an increase in the serum phosphate concentration, ultimately leading to
hyperphosphatemia.