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NCLEX · PN: Physiological Integrity · Topic Study Guide

Fluid and Electrolyte Imbalances: Practice Questions & Explanations

9 PN: Physiological Integrity questions on fluid and electrolyte imbalances, each with a worked explanation citing the source handbook.

Source: NCSBN NCLEX-PN Test Plan (current edition). Physiological Integrity includes Basic Care and Comfort (nutrition, mobility, rest, elimination, non-pharmacological comfort), Pharmacological Therapies (expected effects, adverse effects, medication administration, client education), Reduction of Risk Potential (diagnostic tests, vital signs, lab values, preventing complications), and Physiological Adaptation (altered body systems, fluid and electrolyte imbalances, illness management, medical emergencies).

Why this topic matters

These questions cover this specific topic in depth. Each one cites the source handbook so you can verify and read further.

Below are every fluid and electrolyte imbalances question in our PN: Physiological Integrity bank. Read each question, try to answer before reading the explanation, and use the source citations to look up anything you want to verify in the official handbook.

1. A client with heart failure is assessed for fluid volume excess. Which finding is MOST consistent with this condition?
  1. A Poor skin turgor and dry mucous membranes
  2. B Peripheral edema, crackles in lung bases, weight gain of 2 kg in 2 days, elevated blood pressure, and jugular vein distension
  3. C Decreased urine output with concentrated urine
  4. D Rapid, weak pulse with low blood pressure

Explanation

FLUID VOLUME EXCESS (FVE), also called hypervolemia or fluid overload, occurs when too much fluid is retained in the body. In HEART FAILURE, the failing heart cannot pump blood forward effectively; fluid backs up in the venous system and lungs. HALLMARK SIGNS OF FVE: PERIPHERAL EDEMA — dependent edema (ankles/feet when upright, sacrum when supine); PULMONARY EDEMA — crackles (rales) at lung bases; dyspnea; orthopnea (difficulty breathing when lying flat); paroxysmal nocturnal dyspnea; WEIGHT GAIN — 1 kg ≈ 1 liter of fluid; 2 kg in 2 days is significant (daily weight is the MOST SENSITIVE early indicator of fluid retention); ELEVATED BLOOD PRESSURE — from increased circulating volume; JUGULAR VEIN DISTENSION (JVD) — at 45° head of bed elevation, visible jugular pulsation >2 cm above sternal angle indicates elevated central venous pressure; FULL, BOUNDING PULSE — from increased cardiac output/volume; INCREASED URINE OUTPUT (if kidneys are responding) — or decreased if kidneys are failing; S3 HEART SOUND ('gallop') — associated with heart failure. CONTRAST WITH FLUID VOLUME DEFICIT (FVD/hypovolemia): poor skin turgor; dry mucous membranes; decreased urine output with concentrated urine; tachycardia; decreased BP (orthostatic hypotension); flat neck veins; dizziness; weight loss; weak thready pulse. NURSING INTERVENTIONS for FVE: MONITOR: daily weight (same time, same scale, same clothing), I&O, vital signs, lung sounds, edema; DIURETICS: furosemide (Lasix) most common loop diuretic; FLUID RESTRICTION as ordered; low SODIUM DIET (sodium promotes water retention); POSITION: semi-Fowler's or high-Fowler's for dyspnea; REPORT: rapid weight gain (>1 kg/day), worsening dyspnea or crackles.
Source: NCLEX-PN Test Plan: Physiological — Fluid/Electrolytes, FVE
2. A client's laboratory results show serum calcium of 12.5 mg/dL (normal 8.5-10.5 mg/dL). Which clinical finding is MOST consistent with hypercalcemia?
  1. A Tetany and muscle spasms
  2. B 'Bones, groans, moans, and stones' — bone pain, constipation/nausea, altered mental status/depression, and kidney stones; plus decreased deep tendon reflexes and muscle weakness
  3. C Peaked T waves on ECG
  4. D Positive Chvostek's sign

Explanation

HYPERCALCEMIA is defined as serum calcium >10.5 mg/dL. Normal: 8.5-10.5 mg/dL. A level of 12.5 mg/dL is significantly elevated. CLINICAL MNEMONIC for hypercalcemia: 'BONES, GROANS, MOANS, AND STONES': BONES: bone pain and pathological fractures — calcium is being leached from bones (especially in malignancy or hyperparathyroidism); GROANS: GI symptoms — nausea, vomiting, anorexia, CONSTIPATION (calcium decreases GI motility), abdominal pain; MOANS: neuropsychiatric — confusion, depression, psychosis, altered mental status, DECREASED DEEP TENDON REFLEXES (calcium stabilizes nerve membranes, reducing excitability), muscle weakness, fatigue, lethargy; STONES: kidney stones (calcium oxalate or calcium phosphate) — polyuria, nephrolithiasis, nephrocalcinosis. CARDIAC EFFECTS: shortened QT interval on ECG (calcium shortens repolarization); dysrhythmias in severe cases. CONTRAST WITH HYPOCALCEMIA: TETANY (muscle spasms, cramping); POSITIVE TROUSSEAU'S SIGN (carpal spasm when BP cuff inflated above systolic for 3 minutes); POSITIVE CHVOSTEK'S SIGN (facial muscle twitch when tapping the facial nerve anterior to the ear); PARESTHESIAS (perioral, fingertips); SEIZURES; INCREASED DEEP TENDON REFLEXES; PROLONGED QT INTERVAL on ECG. CAUSES OF HYPERCALCEMIA: MALIGNANCY (most common in hospitalized patients — bone metastases, PTH-related protein secretion); PRIMARY HYPERPARATHYROIDISM (most common cause overall in outpatients); vitamin D toxicity; prolonged immobilization; thiazide diuretics; sarcoidosis; milk-alkali syndrome. TREATMENT: IV NORMAL SALINE (first-line — hydration promotes renal calcium excretion); FUROSEMIDE (after adequate hydration — promotes calciuresis); BISPHOSPHONATES (for malignancy-associated hypercalcemia); CALCITONIN (rapid but temporary); CORTICOSTEROIDS (for vitamin D-related causes, sarcoidosis); DIALYSIS (severe refractory cases). PN ROLE: monitor for symptoms; hydration; fall risk (weakness, confusion); educate on adequate hydration; report severe symptoms or rapidly rising values.
Source: NCLEX-PN Test Plan: Physiological — Fluid/Electrolytes, Hypercalcemia
3. A client receives 2 liters of 0.9% normal saline in 4 hours. The nurse should monitor for which complication?
  1. A Dehydration from the saline
  2. B Fluid volume excess — signs include increasing blood pressure, peripheral edema, crackles in lung bases, weight gain, and dyspnea; 2 liters in 4 hours is a significant fluid bolus that can cause overload, especially in clients with cardiac or renal compromise
  3. C Hyperglycemia
  4. D Hyperthermia

Explanation

FLUID VOLUME EXCESS RISK from IV fluid administration is a significant clinical concern, especially with rapid infusion rates. 2 LITERS IN 4 HOURS = 500 mL/hour — a moderately rapid rate; this is often appropriate in acute resuscitation but requires monitoring for fluid overload. HIGH-RISK POPULATIONS: Heart failure patients (already have fluid overload tendency; reduced cardiac output cannot accommodate extra volume); Renal insufficiency (kidneys cannot excrete excess fluid normally); Elderly patients (reduced cardiac reserve and renal function); Hypoalbuminemia (low oncotic pressure means more fluid shifts to interstitial space). MONITORING FOR FLUID OVERLOAD: RESPIRATORY: Increasing respiratory rate; crackles (rales) in lung bases (fluid accumulating in alveoli); dyspnea; orthopnea; CARDIOVASCULAR: Rising blood pressure; bounding pulse; jugular vein distension; S3 gallop on auscultation; PERIPHERAL: Dependent edema (ankles if upright, sacrum if supine); pitting edema; WEIGHT: Rapid weight gain (1 kg = approximately 1 liter of fluid); URINE OUTPUT: Should increase appropriately with fluid bolus; oliguria despite infusion suggests fluid is not being cleared. INTERVENTION IF OVERLOAD DEVELOPS: Slow or stop the infusion; notify RN/provider; elevate HOB; administer supplemental oxygen; prepare for possible diuretic administration; continuous monitoring.
Source: NCLEX-PN Test Plan: Physiological — Fluid/Electrolytes, IV Fluid Overload Risk
4. A client with heart failure has gained 4 lbs in 2 days and reports increased ankle swelling. How should the nurse interpret this?
  1. A Normal fluctuation requiring no action
  2. B Significant fluid retention — 1 kg of weight gain = approximately 1 liter of fluid retention; 4 lbs ≈ 2 liters of fluid; in a heart failure patient, this indicates worsening fluid volume excess requiring prompt assessment and notification of the provider for medication adjustment
  3. C The client is gaining muscle mass
  4. D Only concerning if the client reports difficulty breathing

Explanation

FLUID WEIGHT MONITORING IN HEART FAILURE: CALCULATION: 1 kg = 1,000 mL of fluid; 1 lb ≈ 0.45 kg; 4 lbs ≈ 1.8 kg ≈ 1.8 liters of additional fluid; HEART FAILURE ALERT WEIGHT: Standard patient teaching: notify provider for weight gain of 2+ lbs in a day or 5+ lbs in a week; this patient has gained 4 lbs in 2 days — exceeds the alert threshold; ASSESSMENT: Assess respiratory status (crackles, dyspnea, orthopnea — fluid moving to the lungs?); assess peripheral edema severity; review current medications (diuretics compliance?); check recent sodium intake; PROVIDER NOTIFICATION: This finding requires prompt provider communication; likely response: increase diuretic dose (furosemide adjustment); sodium restriction reinforcement; possibly additional monitoring or hospitalization if respiratory symptoms present; PN SCOPE: Assess, document, notify RN/provider, implement ordered changes; daily weights are the most sensitive early indicator of fluid status changes.
Source: NCLEX-PN Test Plan: Physiological — Fluid Balance, Heart Failure Weight Monitoring
5. A client on a loop diuretic (furosemide) reports muscle cramps and fatigue. Blood work shows potassium 3.1 mEq/L. Which intervention should the nurse prioritize?
  1. A Encourage rest only
  2. B Report the potassium level to the provider and implement ordered potassium replacement; educate the client on dietary potassium sources; hold the next furosemide dose if ordered until potassium level is addressed — K+ 3.1 is below normal (3.5-5.0) and symptomatic
  3. C Give the scheduled furosemide and monitor
  4. D Increase the furosemide dose

Explanation

HYPOKALEMIA from loop diuretics: NORMAL POTASSIUM: 3.5-5.0 mEq/L; MILD HYPOKALEMIA: 3.0-3.4 mEq/L (client's 3.1 mEq/L is mild); SYMPTOMS: Muscle weakness, cramps, fatigue (matching this client's complaints); SEVERE (<3.0): Potentially fatal cardiac dysrhythmias (PVCs, ventricular fibrillation), severe weakness; ECG CHANGES: Flattened T waves, U waves, prolonged QU interval; INTERVENTION SEQUENCE: Notify provider with lab value and symptoms; HOLD furosemide (adding more diuretic increases potassium loss); REPLACE potassium: Oral KCl preferred when tolerated (less dangerous than IV); IV KCl if severe or oral not possible (NEVER IV push — causes cardiac arrest); DIETARY: Bananas, oranges, melons, potatoes, leafy greens, yogurt; MONITORING: Repeat labs after replacement; cardiac monitoring if K+ <3.0; assess muscle weakness and ECG; RENAL: Ensure adequate renal function before aggressive replacement — hyperkalemia is also dangerous.
Source: NCLEX-PN Test Plan: Physiological — Hypokalemia from Diuretics
6. A post-surgical client has a urine output of 20 mL over the past hour. Normal minimum is 30 mL/hr. What is the LPN's priority action?
  1. A Document and recheck in two hours
  2. B Notify the RN immediately — urine output below 30 mL/hr (oliguria) is a critical finding that may indicate inadequate renal perfusion, hypovolaemia, or acute kidney injury requiring prompt assessment and intervention
  3. C Encourage the client to drink more fluids
  4. D Reassure the client this is normal after surgery

Explanation

OLIGURIA (<30 mL/hr or <0.5 mL/kg/hr): This is a critical assessment finding. CAUSES: Hypovolaemia (most common post-surgical — inadequate fluid replacement, haemorrhage); cardiac output reduction (heart failure, MI); renal causes (ATN, contrast nephropathy); obstruction (kinked catheter — check first); PRE-RENAL vs RENAL: Pre-renal oliguria responds to fluids; renal oliguria does not — distinguishing them guides treatment; IMMEDIATE NURSING ACTIONS: Check catheter for kinks, clots, or position issues (simple fix first); assess vital signs (hypotension + oliguria = volume depletion until proven otherwise); notify RN urgently — this requires medical assessment; ANTICIPATED ORDERS: IV fluid bolus if pre-renal; renal panel, BMP; strict intake/output; PN SCOPE: Assess, check equipment, NOTIFY RN IMMEDIATELY — do not wait; time-sensitive finding.
Source: NCLEX-PN Physiological — Post-op Oliguria, Urinary Output Monitoring
7. A client's serum sodium is 128 mEq/L (normal 135-145). They appear confused and report nausea and headache. What condition does this represent and what is the nursing priority?
  1. A Hypernatraemia — restrict fluids
  2. B Hyponatraemia — notify the RN urgently; severe hyponatraemia causes neurological symptoms from cerebral oedema; the nurse should NOT encourage the client to drink free water (worsens the condition) and should await medical orders for IV sodium replacement
  3. C Hypokalaemia — check the ECG
  4. D Dehydration — give oral fluids freely

Explanation

HYPONATRAEMIA (Na <135 mEq/L): SEVERE (<125 mEq/L): Neurological symptoms — confusion, nausea, headache, seizures, and if untreated, cerebral oedema, herniation, and death; 128 mEq/L with symptoms = URGENT; CAUSES: SIADH (syndrome of inappropriate ADH secretion); heart failure; cirrhosis; excessive hypotonic IV fluids; psychogenic polydipsia; CRITICAL NURSING ACTION: Do NOT give free water or hypotonic fluids (water moves into cells and worsens cerebral oedema); Notify RN immediately; seizure precautions; TREATMENT (physician-ordered): Fluid restriction (most common); hypertonic saline (3% NaCl) for severe symptomatic cases — given only in ICU with strict monitoring; rate of correction must be controlled (correcting too fast causes osmotic demyelination syndrome); MONITORING: Neurological status (confusion, seizure activity); vital signs; serum sodium levels; strict I&O; safety measures (fall precautions for confusion).
Source: NCLEX-PN Physiological — Electrolytes, Severe Hyponatraemia
8. A client has a serum sodium level of 122 mEq/L (normal 135-145). Which assessment finding would the nurse expect with this level of hyponatremia?
  1. A Extreme thirst and dry mucous membranes
  2. B Neurological changes — confusion, headache, lethargy, muscle weakness, and in severe cases seizures; severe hyponatremia causes cerebral edema as water shifts into brain cells
  3. C Flushed dry skin
  4. D Increased urine output with high specific gravity

Explanation

HYPONATREMIA (low sodium, <135 mEq/L): 122 mEq/L is significantly low. NEUROLOGICAL EFFECTS DOMINATE: Sodium imbalances primarily affect the brain because water shifts based on sodium concentration; LOW SODIUM = water moves INTO cells (including brain cells) = cerebral edema; SYMPTOMS by severity: Mild: headache, nausea, malaise; Moderate: confusion, lethargy, muscle weakness, disorientation; Severe (<120): seizures, coma, respiratory arrest, death; CAUSES: SIADH, excessive water intake, diuretics, heart failure, vomiting/diarrhea with water replacement; TREATMENT: Depends on cause and severity — fluid restriction (if dilutional), careful sodium replacement (hypertonic saline for severe symptomatic cases — corrected SLOWLY to avoid osmotic demyelination syndrome); SAFETY: Seizure precautions for severe hyponatremia; LPN role: monitor neuro status, report changes, implement safety measures.
Source: NCLEX-PN Physiological — Fluid/Electrolytes, Hyponatremia
9. A client receiving IV potassium chloride (KCl) reports burning at the IV site. What should the nurse do first?
  1. A Increase the infusion rate to flush it through faster
  2. B Slow or stop the infusion and assess the site — KCl is irritating to veins; burning may indicate the rate is too fast or infiltration; KCl is NEVER given IV push (causes fatal cardiac arrest) and must be diluted and infused slowly via pump
  3. C Apply heat to the site
  4. D Document and continue the infusion

Explanation

IV POTASSIUM SAFETY — A HIGH-ALERT MEDICATION: KCl is irritating to veins and dangerous if administered incorrectly. BURNING at the site: Slow or stop the infusion; assess for infiltration; KCl is a vein irritant — slower rates and greater dilution reduce burning; consider a central line for higher concentrations; NEVER IV PUSH: Concentrated IV potassium push causes immediate fatal cardiac arrest (cardioplegia) — KCl must ALWAYS be diluted and infused slowly; ADMINISTRATION RULES: Maximum peripheral concentration and rate per protocol (typically not exceeding 10 mEq/hour peripherally without cardiac monitoring); always use an infusion pump; never bolus; CARDIAC MONITORING: For higher rates or concentrations; HYPERKALEMIA RISK: Too much/too fast potassium causes hyperkalemia → peaked T waves, widened QRS, fatal dysrhythmias; ASSESS renal function before administration (impaired kidneys can't excrete potassium); LPN role: monitor IV site, infusion rate, never administer KCl IV push, report burning or cardiac symptoms.
Source: NCLEX-PN Physiological — Fluid/Electrolytes, IV Potassium Safety

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