Electrolyte Imbalances.NCLEX Quick-Reference Cheat Sheet

Hyponatremia (Na⁺ <135)

Signs	confusion, headache, cramps, seizures, N/V
Causes	SIADH, excess water, diuretics, vomiting
Treat	fluid restriction; 3% saline (severe, SLOW)

Correct slowly (osmotic demyelination).

Hypernatremia (Na⁺ >145)

Signs	thirst, agitation, dry mucosa, seizures
Causes	water loss, DI, ↑Na intake, fever
Treat	water (hypotonic IV slow); restrict Na

Think 'salty & dry.'

Hypokalemia (K⁺ <3.5)

Signs	weakness, flat T/U wave, ileus, dysrhythmia
Causes	diuretics, vomiting, NG suction, insulin
Treat	replace K⁺ — NEVER IV push, on a pump

Ensure urine output before replacing.

Hyperkalemia (K⁺ >5.0)

Signs	peaked T, wide QRS, weakness, arrest
Causes	renal failure, K-sparing diuretics, acidosis
Treat	Ca gluconate, insulin+D50, kayexalate, dialysis

Ca gluconate protects the heart first.

Hypocalcemia (Ca²⁺ <9)

Signs	+Chvostek/Trousseau, tetany, ↑DTR, spasm
Causes	hypoparathyroid, thyroidectomy, ↓vit D
Treat	calcium; vitamin D; airway/seizure precautions

Tetany + tingling = low calcium.

Hypercalcemia (Ca²⁺ >10.5)

Signs	weakness, ↓DTR, stones, constipation, confusion
Causes	hyperparathyroid, malignancy, immobility
Treat	IV fluids + loop diuretic; bisphosphonates

'Bones, stones, groans, moans.'

Hypomagnesemia (Mg²⁺ <1.5)

Signs	tremor, hyperreflexia, +Chvostek, torsades
Causes	alcohol use, malnutrition, diarrhea, diuretics
Treat	replace Mg; monitor cardiac rhythm

Mirrors low calcium; common in alcohol use.

Hypermagnesemia (Mg²⁺ >2.5)

Signs	↓DTR, hypotension, bradycardia, resp depression
Causes	renal failure, Mg antacids, OB mag therapy
Treat	stop Mg; calcium gluconate (antidote); fluids

Loss of reflexes = early warning.

Key Rules

Ca ↔ Phos	inversely related (one up, other down)
Mg & Ca	behave alike (both low = tetany)
K⁺ & Ca²⁺	extremes = cardiac monitoring priority

Educational quick-reference only; values/ranges vary by source. Verify against your facility and the current NCSBN test plan.