Sodium (135-145 mEq/L)

• The major cation in the ECF. It has a water retaining effect. When there is excess Na+ in the ECF, more water will be reabsorbed by the kidneys.
• Functions: maintains body fluids, conduction of neuromuscular impulses via pump, regulates acid-base balance by combining with Cl- or HCO3-.

Hyponatremia

• Causes: vomiting, diarrhea, NG suction, excessive perspiration, kidney disease, water intoxication, IV D5W, SIADH, burns
• Signs and Symptoms: apprehension, muscular weakness, postural hypotension, N/V, dry mucous membranes, tachycardia
• Treatment: water restriction, normal saline IV

Hypernatremia

• Causes: excessive salt intake, dehydration, CHF, hepatic failure (excess aldosterone secretion), diabetes insipidus
• Signs and Symptoms: extreme thirst, sticky mucous membranes, dry tongue, fever, postural hypotension, restlessness/agitation/irritability, increased fluid retention/edema, decreased urine output, convulsions
• Treatment: stop IV normal saline, replace water loss

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Potassium (3.5-5.0 mEq/L)

• The major ICF electrolyte, 80%-90% is excreted by the kidneys.
• When tissue breaks down, K+ leaves the cells and enters the ECF and is excreted by the kidneys
• The body does not conserve K+
• Influences both skeletal and cardiac muscle activity

Hypokalemia

• ** The most common electrolyte imbalance
• Causes: vomiting/diarrhea, renal disorder, sweating, crash diets, diuretics
• S/S: fatigue, anorexia, N/V, muscle weakness, decreased bowel motility, cardiac dysrhythmias, paresthesia or tender muscles
• Treatment: administer KCl (never give K+ undiluted or IV push. concentrated solutions should be administered through central veins. Use IV pump!)

Hyperkalemia

• Causes: renal failure, potassium supplements, digoxin toxicity, potassium sparing diuretics, acidosis (DKA), fluid volume deficit. 
• S/S: anxiety, cardiac arrhythmias (bradycardia, heart block, peaked T wave, widened QRS), muscle weakness, abdominal cramps, diarrhea
• Treatment: dialysis, Kayexalate, stop supplements

Calcium (4.5-5.3 mg/dL)

• Ionized (free Calcium) is Calcium not attached to proteins.
• 99% is located in skeletal system, 1% in serum
• Necessary for bone and teeth formation
• Necessary for the transmission of nerve impulses and contraction of the myocardium and skeletal muscles
• Causes blood clotting by converting prothrombin into thrombin
• Strengthens capillary membranes

Hypocalcemia

• Causes: lack of Ca and Vit D in diet, extensive infection, hypoparathyroidism, pancreatitis, chronic renal failure (Phosphorus rises/calcium declines)
• S/S: Related to diminished neuromuscular and cardiac function – positive Trousseau’s sign, positive Chvostek’s sign, numbness of fingers and around mouth, hyperactive reflexes, tetany, convulsion, spasms/muscle cramps, arrhythmia/ventricular tachycardia. (CATS: convulsions, arrhythmias, tetany, spasms)
• Treatment: Oral/IV replacement, correct underlying cause

Hypercalcemia

• Causes: hyperparathyroidism, neoplasm, osteoporosis, prolonged immobilization
• S/S: anorexia, N/V, lethargy, flank pain from kidney stones, cardiac arrhythmias (heart block, eventual cardiac arrest), muscle flaccidity
• Treatment: Calcitonin, discontinue antacids, treatment of underlying cause

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Phosphate (2.7-4.5 mg/dL)

• buffer found primarily in ICF
• functions: acid-base regulation, phosphate and calcium help with bone and teeth development, promotes normal neuromuscular action and participates in CHO metabolism, conversion of glycogen to glucose
• normally absorbed in the GI tract, regulated by diet, renal excretion, intestinal absorption and PTH

Hypophosphatemia

• Cause: excretion
• Symptoms: disorientation, bruising, numbness, bone pain, muscle weakness
• Treatment: increase dietary intake, IV replacement

Hyperphosphatemia

• Causes: decreased intake or increased excretion
• S/S: same as hypocalcemia
• Treatment: limit phosphate intake, administer aluminum-based antacids.

Chloride (98-106 mEq/L)

• anion found mostly in ECF, maintains body water balance, plays a role in acid-base balance, combines with H+ to produce acidity in the stomach
• follows Na+ up or down

Hypochloremia

• Causes: vomiting, diarrhea, excessive NG drainage, hypokalemia, hyponatremia, adrenal gland deficiency
• S/S: hyperexcitabilty of the nervous system and muscles, tetany
• Treatment: treat underlying cause

Hyperchloremia

• Causes: dehydration, hypernatremia, kidney dysfunction, head injury, hyperparathyroidism
• S/S: deep, rapid, vigorous breathing, lethargy, weakness
• Treatment: decrease intake, correct underlying cause

Magnesium (1.5-2.5 mEq/L)

• Most plentiful in the cells
• Needed for neuromuscular activity
• Responsible for the transport of Na and K across the cell membrane

Hypomagnesemia

• Causes: protein malnutrition, alcoholism/cirrhosis of the liver, aldosterone excess, inadequate absorption (chronic diarrhea, vomiting, NG drainage)
• S/S: muscle tremors, hyperactive tendon reflexes, confusion, tachycardia
• Treatment: treat underlying causes, IV replacement if necessary.

Hypermagnesemia

• Causes: severe dehydration, renal failure, leukemia, antacids/laxatives
• S/S: flushing, muscular weakness, increased perspiration, cardiac arrhythmias (bradycardia, prolonged QT intervals, AV block)
• Treatment: treat underlying cause

Helpful Tidbits

• 4 electrolytes that impact cardiac functioning: K, Mg, Ca, Ph
• 3 imbalances that contribute to digoxin toxicity: hypokalemia, hypercalcemia, hypomagnesmia
• 4 imbalances that contribute to seizures: hyponatremia, hypocalcemia, hypomagnesmia, hyperphosphatemia
• Electrolytes associated with alkalosis: hypomagnesemia, hypokalemia
• Clinical Dehydration = ECV Deficit + Hypernatremia

Source: Texas Woman’s University College of Nursing, Fundamentals of Nursing – Perry & Potter 2016

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