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NCLEX Fluids and Electrolytes Practice Questions
Fluid and electrolyte imbalances run through almost every med-surg topic, and they are one of the areas where memorising normal ranges directly earns points.
These questions test normal values, the signs of each imbalance and the safe nursing response.
What the NCLEX tests in fluids and electrolytes
- Normal ranges for potassium, sodium, calcium and magnesium
- ECG changes with potassium imbalances
- Fluid volume excess versus deficit
- IV potassium safety
- Chvostek and Trousseau signs
5 fluids and electrolytes practice questions with rationales
Answer each one before opening the rationale. Every option is explained, including the wrong ones.
- 3.8 mEq/L
- 4.2 mEq/L
- 4.9 mEq/L
- 6.1 mEq/L
Show answer and rationale
Answer: D
A. Within the normal range of about 3.5 to 5.0 mEq/L.
B. Normal.
C. Normal, near the upper limit.
D. Correct. Hyperkalemia above 5.0 risks dangerous dysrhythmias.
- Tall, peaked T waves
- U waves
- Widened QRS with peaked T waves
- ST elevation
Show answer and rationale
Answer: B
A. Peaked T waves suggest hyperkalemia.
B. Correct. Low potassium causes flattened T waves and U waves.
C. Hyperkalemia pattern.
D. ST elevation suggests myocardial injury.
- Bounding pulse
- Crackles in the lungs
- Weight gain
- Poor skin turgor
- Distended neck veins
Show answer and rationale
Answer: A, B, C, E
A. Correct. Increased volume strengthens the pulse.
B. Correct. Fluid enters the lungs.
C. Correct. Retained fluid adds weight.
D. Poor turgor suggests deficit, not excess.
E. Correct. JVD reflects venous congestion.
- 20 mEq PO with food
- 10 mEq diluted in IV fluid on an infusion pump
- 20 mEq IV push
- 40 mEq PO in divided doses
Show answer and rationale
Answer: C
A. Oral potassium with food reduces GI upset; safe.
B. Diluted and pumped is the safe IV route.
C. Correct. Potassium is never given IV push; it can cause cardiac arrest.
D. Divided oral doses are acceptable.
- Positive Trousseau sign
- Positive Chvostek sign
- Muscle weakness and decreased reflexes
- Tingling around the mouth
- Muscle cramps or tetany
Show answer and rationale
Answer: A, B, D, E
A. Correct. Carpal spasm with a BP cuff inflated.
B. Correct. Facial twitch when the facial nerve is tapped.
C. Weakness and decreased reflexes suggest hypercalcemia.
D. Correct. Perioral paresthesia is common.
E. Correct. Low calcium increases neuromuscular excitability.
How to study fluids and electrolytes for the NCLEX
- Learn the normal ranges first: K 3.5 to 5.0, Na 135 to 145, Ca about 9 to 10.5 mg/dL, Mg about 1.5 to 2.5 mEq/L (check your program's ranges).
- Potassium and the heart go together: any abnormal potassium question is really a cardiac safety question.
- Low calcium and low magnesium both make nerves twitchy; high levels make them sluggish.
Frequently asked questions
Potassium and sodium most often, followed by calcium and magnesium, usually in the context of a disease or medication.
Yes. The exam gives values without ranges in many questions, so you need the common ranges memorised.
Yes. Upload your notes to NurseQuizAI to generate questions on exactly what your course covers.