🎯 High-Yield Points for This Topic
- Na+ 135-145: hyponatraemia = confusion, seizures; hypernatraemia = thirst, dry mucous membranes
- K+ 3.5-5.0: hypokalaemia = muscle weakness, arrhythmias; hyperkalaemia = peaked T waves
- Ca++ 8.5-10.5: hypocalcaemia = Chvostek/Trousseau signs, tetany
- Dehydration: decreased urine output, increased urine specific gravity, dry mucous membranes
- IV fluids: isotonic = NS/LR; hypotonic = 0.45% NS; hypertonic = 3% NS (only in ICU)
[Infographic: Fluid & Electrolyte NCLEX Questions Key Concepts — Clinical Manifestations, Nursing Interventions, Priority Actions]
Practice Questions
Question 1
A client with hyponatraemia (sodium 118 mEq/L) is confused and agitated. Which IV fluid does the nurse anticipate administering?
✓ Correct: Hypertonic 3% sodium chloride
Symptomatic severe hyponatraemia (Na+ <120 with neurological symptoms) requires careful correction with hypertonic saline (3% NaCl) in an ICU setting. The nurse must never correct sodium too rapidly — maximum 8-12 mEq/L per 24 hours — to prevent osmotic demyelination syndrome (central pontine myelinolysis). This is a critical safety consideration.
Symptomatic severe hyponatraemia (Na+ <120 with neurological symptoms) requires careful correction with hypertonic saline (3% NaCl) in an ICU setting. The nurse must never correct sodium too rapidly — maximum 8-12 mEq/L per 24 hours — to prevent osmotic demyelination syndrome (central pontine myelinolysis). This is a critical safety consideration.
Question 2
A nurse assesses a client with chronic kidney disease and finds peaked T waves on the cardiac monitor. Which electrolyte imbalance is MOST likely?
✓ Correct: Hyperkalaemia
Peaked T waves are the classic ECG sign of hyperkalaemia. CKD impairs potassium excretion, leading to dangerous potassium accumulation. Hyperkalaemia progression: peaked T waves → widened QRS → sine wave pattern → ventricular fibrillation. This is a medical emergency. Hypokalaemia causes flattened T waves and U waves, not peaked T waves.
Peaked T waves are the classic ECG sign of hyperkalaemia. CKD impairs potassium excretion, leading to dangerous potassium accumulation. Hyperkalaemia progression: peaked T waves → widened QRS → sine wave pattern → ventricular fibrillation. This is a medical emergency. Hypokalaemia causes flattened T waves and U waves, not peaked T waves.
Question 3
A client with severe diarrhoea for 4 days is assessed. Which finding is most consistent with dehydration?
✓ Correct: Urine specific gravity of 1.030
Urine specific gravity of 1.030 indicates highly concentrated urine — a sign of dehydration and the kidneys conserving fluid. Normal specific gravity is 1.005-1.030; at 1.030, the kidneys are maximally concentrating urine. The blood pressure and sodium are still normal (compensated dehydration), and urine output 60 mL/hour is adequate. Urine concentration is an early, sensitive indicator of fluid deficit.
Urine specific gravity of 1.030 indicates highly concentrated urine — a sign of dehydration and the kidneys conserving fluid. Normal specific gravity is 1.005-1.030; at 1.030, the kidneys are maximally concentrating urine. The blood pressure and sodium are still normal (compensated dehydration), and urine output 60 mL/hour is adequate. Urine concentration is an early, sensitive indicator of fluid deficit.
Question 4
A client is prescribed potassium chloride (KCl) 40 mEq IV for hypokalaemia. Which action by the nurse is CORRECT?
✓ Correct: Dilute in 100 mL and infuse via infusion pump over 1-2 hours
Potassium chloride MUST NEVER be given as IV push — rapid IV administration causes fatal cardiac arrhythmias. KCl must be diluted (never more than 10 mEq/100 mL) and administered via infusion pump at a controlled rate (not faster than 10-20 mEq/hour). It must be given through a peripheral or central line, never undiluted. This is a critical patient safety rule.
Potassium chloride MUST NEVER be given as IV push — rapid IV administration causes fatal cardiac arrhythmias. KCl must be diluted (never more than 10 mEq/100 mL) and administered via infusion pump at a controlled rate (not faster than 10-20 mEq/hour). It must be given through a peripheral or central line, never undiluted. This is a critical patient safety rule.
Question 5
A postoperative client develops sudden neck muscle spasms and reports tingling around the mouth after thyroid surgery. Which electrolyte does the nurse suspect is low?
✓ Correct: Calcium
Tingling around the mouth (circumoral paraesthesia), muscle spasms (tetany), and the recent thyroid surgery strongly suggest hypocalcaemia. The parathyroid glands (which regulate calcium) may be inadvertently damaged or removed during thyroidectomy, causing acute hypocalcaemia. Positive Chvostek sign (facial twitch) and Trousseau sign (carpal spasm with BP cuff) would further confirm this. Emergency calcium gluconate IV may be required.
Tingling around the mouth (circumoral paraesthesia), muscle spasms (tetany), and the recent thyroid surgery strongly suggest hypocalcaemia. The parathyroid glands (which regulate calcium) may be inadvertently damaged or removed during thyroidectomy, causing acute hypocalcaemia. Positive Chvostek sign (facial twitch) and Trousseau sign (carpal spasm with BP cuff) would further confirm this. Emergency calcium gluconate IV may be required.
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[Clinical Concept Map: Fluid & Electrolyte NCLEX Questions — Pathophysiology, Assessment Findings, Nursing Actions]