Cheat sheets › Fluids & electrolytes

Electrolyte imbalances cheat sheet

Electrolyte questions reward pattern recognition: peaked T waves point to high potassium, U waves to low potassium, and a positive Trousseau sign to low calcium.

Match the sign to the electrolyte, then pick the nursing action.

Built from NurseLingo's RN-written study decks· Updated Oct 2026· Sources

Imbalance	Key Signs	Nurse Move
Hypokalemia	Low K+: weakness & dysrhythmias	U waves on ECG Flaccid paralysis risk Never give K+ IV push
Hyperkalemia	High K+: cardiac danger	Peaked T waves, wide QRS Cramps, tingling, then weakness Anticipate calcium gluconate
Hyponatremia	Low Na+: neuro symptoms	Confusion, lethargy Headache, nausea Seizures if severe
Hypernatremia	High Na+: thirst & dryness	Intense thirst Dry sticky mucosa Restlessness to seizures
Hypocalcemia	Low Ca++: tetany signs	Trousseau & Chvostek + Tingling, tetany Prolonged QT
Hypercalcemia	High Ca++: bones, stones	Bone pain, kidney stones Constipation, confusion Muscle weakness
Hypomagnesemia	Low Mg++: seizure & torsades risk	Tremors, hyperreflexia Torsades risk Anticipate IV mag sulfate
Hypermagnesemia	High Mg++: reflexes go down	Decreased DTRs Hypotension, bradycardia Watch for resp depression
Post-Thyroidectomy	Watch for parathyroid injury	Tingling, Trousseau sign Check calcium levels Notify provider fast
Dig + Furosemide	Low K+ potentiates dig toxicity	Watch nausea, visual changes Monitor potassium closely

RN pearl: ECG changes are clues; the serum level confirms. Match the sign to the electrolyte, then act.

Watch: Electrolyte imbalances explained

▶ Fluid and Electrolytes Made Easy for Nursing Students · 17:30 · free on the Nurse Lingo YouTube channel

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Test yourself: fluid and electrolyte practice questions (free, answers and rationales included).

Frequently asked questions

What ECG changes does hyperkalemia cause?

Tall, peaked T waves and a widening QRS. Anticipate calcium gluconate to protect the heart.

What are the signs of hypocalcemia?

Tingling, tetany, positive Trousseau and Chvostek signs, and a prolonged QT interval. Watch for it after thyroid surgery.

Why is potassium never given IV push?

A rapid dose of potassium can cause a fatal cardiac arrhythmia. IV potassium is diluted and given by infusion.

What are the signs of magnesium toxicity?

Deep tendon reflexes decrease first, followed by hypotension, bradycardia and respiratory depression.

Keep studying

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Sources

Medical-Surgical Nursing, 10.3 Electrolyte Imbalance, OpenStax
Fundamentals of Nursing, 20.1 Fluid and Electrolyte Balances, OpenStax
Pharmacology for Nurses, 5.2 Electrolytes, OpenStax
High potassium level, MedlinePlus, U.S. National Library of Medicine

For study only, not medical advice. Ranges and protocols vary by facility; follow your program and facility policies.