I. Introduction: Why Electrolytes Matter on the NCLEX
Electrolyte imbalances can trigger seizures, arrhythmias, respiratory failure or death. On the NCLEX you’ll be asked to recognize abnormal lab values, link them to clinical signs, and choose safe interventions. This guide breaks down the four most‑tested electrolytes—sodium, potassium, calcium and magnesium—using quick‑reference tables and memory aids. Look for the placeholder link below, which will lead to an in‑depth electrolyte article once published.
🎯 Free NCLEX quiz!
See how well you can spot the signs of imbalance, try our Electrolyte Quiz.
Understanding electrolyte physiology isn’t just academic - rapid correction of severe imbalances can save a patient’s life, while inappropriate interventions (like pushing IV potassium too quickly) can be fatal. Keep this cheat sheet handy as you practice lab‑value questions and develop care plans.
II. Normal Electrolyte Ranges at a Glance
| Electrolyte | Normal Range | Primary Function | Mnemonic (Too High) | Mnemonic (Too Low) |
|---|---|---|---|---|
| Sodium (Na⁺) | 135–145 mEq/L | Fluid balance, nerve conduction | FRIED SALT | SALT LOSS |
| Potassium (K⁺) | 3.5–5.0 mEq/L | Cardiac & neuromuscular function | MURDER | A SIC WALT |
| Calcium (Ca²⁺) | 8.5–10.5 mg/dL | Bone, muscle & nerve function | BACK ME | CATS |
| Magnesium (Mg²⁺) | 1.5–2.5 mEq/L | Enzyme reactions, cardiac rhythm | MAG Is Just LOw | Twitches & Torsades |
III. Sodium (Na⁺) Disorders
A. Hypernatremia > 145 mEq/L
Mnemonic: FRIED SALT
Fever, flushed skin • Restlessness • Increased fluid retention/BP • Edema • Decreased urine output • Skin dry • Agitated • Low‑grade fever • Thirst
- Causes: Water loss (DI, fever), excessive Na⁺ intake (IV hypertonic solutions).
- Interventions: Slow IV hypotonic fluids (0.45 % NS), diuretics for sodium excretion, seizure precautions.
B. Hyponatremia < 135 mEq/L
Mnemonic: SALT LOSS
Seizures • Abdominal cramps • Lethargy • Tendon reflexes diminished • Loss of urine/Appetite • Orthostatic hypotension • Spasm • Shallow respirations
- Causes: SIADH, diuretics, GI losses, diluted feedings in infants.
- Interventions: Hypertonic 3 % saline for severe neuro symptoms, restrict fluid, monitor neuro status.
IV. Potassium (K⁺) Disorders
A. Hyperkalemia > 5.0 mEq/L
Mnemonic: MURDER
Muscle cramps • Urine abnormalities • Respiratory distress • Decreased cardiac contractility • ECG changes (peaked T‑waves) • Reflexes decreased
- Causes: Renal failure, potassium‑sparing diuretics, ACE inhibitors, burns.
- Interventions: IV calcium gluconate (stabilizes myocardium), insulin + dextrose (pushes K⁺ into cells), Kayexalate, dialysis if severe.
B. Hypokalemia < 3.5 mEq/L
Mnemonic: A SIC WALT
Alkalosis • Shallow respirations • Irritability • Confusion • Weakness • Arrhythmias (U‑waves) • Lethargy • Thready pulse
- Causes: Vomiting, NG suction, diuretics, hyperaldosteronism.
- Interventions: Oral KCl (with food), IV potassium (never push, max 10 mEq/hr peripherally), monitor ECG and magnesium (Mg²⁺ must be corrected for K⁺ to stabilize).
V. Calcium (Ca²⁺) Disorders
A. Hypercalcemia > 10.5 mg/dL
Mnemonic: BACK ME
Bone pain • Arrhythmias • Cardiac arrest • Kidney stones • Muscle weakness • Excessive urination
- Causes: Hyperparathyroidism, bone malignancy, thiazide diuretics.
- Interventions: IV fluids + loop diuretics, calcitonin, bisphosphonates, encourage ambulation.
B. Hypocalcemia < 8.5 mg/dL
Mnemonic: CATS
Convulsions • Arrhythmias • Tetany (Trousseau & Chvostek) • Spasm/Stridor
- Causes: Hypoparathyroidism, pancreatitis, vitamin D deficiency.
- Interventions: IV calcium gluconate, vitamin D supplements, seizure precautions.
VI. Magnesium (Mg²⁺) Disorders
A. Hypermagnesemia > 2.5 mEq/L
Mnemonic: MAG Is Just LOw
Muscle weakness • **Absent DTRs • GI/Nausea • **Irregular pulse • Jugular vein distention • **LO*w BP/HR
- Causes: Renal failure, excessive antacids/laxatives containing Mg²⁺, adrenal insufficiency.
- Interventions: IV calcium gluconate to oppose Mg²⁺ effect, loop diuretics, dialysis if severe.
B. Hypomagnesemia < 1.5 mEq/L
Mnemonic: “Twitches & Torsades”
Tremors, twitching, tetany; risk of torsades de pointes.
- Causes: Alcoholism, malnutrition, diarrhea, diuretics.
- Interventions: Oral/IV magnesium sulfate (monitor deep tendon reflexes), seizure precautions, correct potassium concurrently.
VII. Putting It All Together: Nursing Actions & Labs
- Trend lab results: Compare daily electrolytes to identify subtle imbalances.
- Monitor ECG: Hyper‑ or hypokalemia can cause lethal arrhythmias; calcium and magnesium disturbances may prolong QT intervals.
- Assess neuromuscular status: Tetany, muscle weakness, changes in reflexes all hint at Ca²⁺ or Mg²⁺ issues.
- Evaluate fluid balance: Intake/output, daily weights and vital signs reveal hidden losses or overloads.
- Educate patients: Dietary sources (bananas for potassium, dairy for calcium), medication effects (diuretics, ACE inhibitors) and when to call the provider.
VIII. Mnemonics Master List (Quick Reference)
| Electrolyte | High Mnemonic | Low Mnemonic |
|---|---|---|
| Na⁺ | FRIED SALT | SALT LOSS |
| K⁺ | MURDER | A SIC WALT |
| Ca²⁺ | BACK ME | CATS |
| Mg²⁺ | MAG Is Just LOw | Twitches & Torsades |
IX. Final Thoughts & Next Steps
Electrolyte imbalances are high‑yield because they influence every body system. Use these mnemonics and quick‑reference charts to recognize abnormal lab values and intervene quickly. Once our comprehensive electrolyte guide (link placeholder above) goes live, you’ll have printable tables and practice scenarios to reinforce your knowledge.
Continue strengthening your NCLEX prep with these GoodNurse resources:
- Cardiac Arrhythmias Cheat Sheet: Interpret ECG rhythms and apply life‑saving interventions.
- Pediatric Nursing Growth & Development Milestones: Track normal development and recognize red flags.
- NCLEX Pharmacology Made Simple – Part 3: Review high‑yield drugs and dosage calculations.
- Best Nursing Mnemonics for NCLEX Success: Memory hacks for complex NCLEX topics.
Bookmark this page, practice daily lab‑value questions and use GoodNurse’s adaptive quizzes to track your progress. Mastering electrolytes means fewer exam surprises—and safer patient care.
