NCLEX Review: Fluid and Electrolytes

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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November 16, 2019 by Nurse Skyanne

As I countdown the days until graduation, and even more so count down the days until I take the state boards, the mix of nervousness and excitement running through my veins is increasing at an exponential rate. I am beyond thrilled that I accepted my dream residency position at a level one trauma center. I’m… Read more
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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

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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