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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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
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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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Nursing Student Summer Tips!

Off for the summer? Here are some productive things you can do! ⛱🌻

1. Do practice NCLEX questions. Yawn. Who wants to do work over the summer? Start by setting a small goal such as 10 questions/day. You’ll find that it won’t take up too much of your time! By the time summer is over, you’ll have done hundreds of questions. I use Saunder’s NCLEX-RN Comprehensive Review for every class and it works wonders! Get a copy of it here!

You can also use Brilliant Nurse NCLEX-RN® Test Prep!, which is an online interactive experience to prep you for the NCLEX!

2. Update your resume. This can be difficult during the busy school year! Take some time to really go through your resume and send it to a few trusty people for advice.

3. Look for internships and jobs. Set aside some time to gather up information about internships and jobs. Apply for what you can and get your name out there! What is your ideal unit? What is your ideal salary? 

4. Review tough topics. Did you have a hard time with the endocrine system? Cardiac? Psych? You’re not alone. Look over some of these topics in a stress-free environment. No pressure, no due dates, no exams! You may remember more material this way. Go with 20 minutes a few times a week.

5. Relaxxxxxx. You’ve been working so hard. Plan time to treat yo self! 

Happy Summer!⭐️⛱



This post may contain affiliate links. This means that, at no cost to you, I may make a commission if you click through and make a purchase. Contact me with any questions!