A nurse is caring for a patient with acute leukemia who deve… | 마이메르시 MyMerci
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문제

A nurse is caring for a patient with acute leukemia who develops tumor lysis syndrome. Which laboratory finding requires the most immediate intervention?

해설
Severe hypocalcemia (calcium 6.2 mg/dL) in tumor lysis syndrome requires immediate intervention due to risk of life-threatening tetany, laryngospasm, and cardiac arrhythmias. Other electrolyte imbalances (hyperuricemia, hyperphosphatemia, hyperkalemia) also need management but are less immediately life-threatening.

심화 해설

Core Nursing Explanation Key Concept Analysis: This question tests the nurse's ability to prioritize life-threatening complications of Tumor Lysis Syndrome (TLS). TLS is an oncologic emergency caused by the rapid breakdown of a large number of tumor cells (e.g., after chemotherapy for acute leukemia), releasing intracellular contents into the bloodstream. This leads to the classic "2H2L" electrolyte abnormalities: Hyperuricemia, Hyperkalemia, Hyperphosphatemia, and Hypocalcemia. The priority is always based on the ABCs (Airway, Breathing, Circulation) and which abnormality poses the most immediate threat to these vital functions.

Answer Rationale: The correct answer is option ④, a serum calcium level of 6.2 mg/dL (normal: 9.0-10.5 mg/dL). Key Point! While all TLS lab values are dangerous, severe hypocalcemia is the most immediate threat because it can cause tetany, laryngospasm (compromising the airway), and life-threatening cardiac arrhythmias (e.g., prolonged QT interval, ventricular fibrillation). A calcium level this low requires urgent IV calcium replacement to stabilize cardiac and neuromuscular function.

Distractor Analysis:
  • Option ①: Serum uric acid 12 mg/dL. Watch out for confusion! Hyperuricemia is a hallmark of TLS and can cause acute kidney injury from uric acid crystal precipitation in the renal tubules. Management (hydration, allopurinol, rasburicase) is critical but is generally not as immediately life-threatening as cardiac instability from hypocalcemia or hyperkalemia.
  • Option ②: Serum phosphorus 8.5 mg/dL. Hyperphosphatemia contributes to hypocalcemia (as phosphate binds with calcium) and also risks renal damage from calcium phosphate crystal deposition. While serious, its primary danger is often indirect, via worsening hypocalcemia and renal failure, which develops over hours.
  • Option ③: Serum potassium 5.8 mEq/L. Key Point! Hyperkalemia is a major immediate threat as it can cause fatal cardiac arrhythmias (e.g., peaked T waves, ventricular fibrillation). However, a level of 5.8 mEq/L is considered moderate. Immediate intervention (e.g., calcium gluconate, insulin/glucose, kayexalate) is typically triggered at levels >6.0 mEq/L or with ECG changes. In this specific set of values, the profound hypocalcemia (6.2 mg/dL) presents a more acute combined risk for arrhythmia.
Related Concepts: The nursing priority follows the principle of treating the most immediate threat to vital functions. In TLS, the cascade is: Hyperkalemia/Hypocalcemia (cardiac/airway threat) > Hyperuricemia/Hyperphosphatemia (renal threat). Prevention with aggressive IV hydration and monitoring is key.

Concept Summary Tumor Lysis Syndrome (TLS): Metabolic emergency from rapid cell death.
Causes: "2H2L" - Hyperuricemia, Hyperkalemia, Hyperphosphatemia, Hypocalcemia.
Pathophysiology: Intracellular contents (K+, PO4-, nucleic acids) flood bloodstream; PO4- binds Ca2+.
Priority: Airway and Cardiac Stability First (Hypocalcemia, Hyperkalemia) > Renal Protection (Hyperuricemia, Hyperphosphatemia).

Side-by-Side Comparison!
AbnormalityPrimary DangerImmediate Nursing Action
Hyperkalemia (K+ >5.0 mEq/L)Cardiac arrhythmia (Peaked T waves, V-fib)ECG monitoring. Administer IV calcium gluconate (cardioprotective), insulin/glucose, albuterol, kayexalate.
Hypocalcemia (Ca2+ Renal (Uric acid, Phos) > Urine output > Seizure precautions (from hypocalcemia) > Hydration.
Mnemonic for 2H2L: "High Kills, High Phosphorus Lowers Calcium, Lots of Uric acid" (HyperKalemia, HyperPhosphatemia -> HypoCalcemia, HyperUricemia).

High-Frequency NCLEX Topics TLS is a classic NCLEX-RN "priority" or "delegation" question. You must know: 1. The "2H2L" lab abnormalities. 2. That hypocalcemia and hyperkalemia are the most immediate threats. 3. The primary preventive measure: Aggressive IV hydration before and during chemotherapy. 4. The role of medications: allopurinol (prophylaxis) vs. rasburicase (treatment for severe hyperuricemia).

Watch Out for Question Variations! * Instead of "Which lab value?", they may ask: "The nurse should prepare to administer which medication first?" → Answer: IV calcium gluconate (for hypocalcemia/hyperkalemia). * "Which patient is at highest risk for TLS?" → Answer: A patient with a high-grade lymphoma or acute leukemia receiving initial chemotherapy. * "What is the priority nursing intervention for a patient at risk for TLS?" → Answer: Ensure aggressive IV hydration and monitor I&O (Intake and Output) to promote excretion of waste products.

임상 시나리오

Nursing Clinical Practice Guide Clinical Scenario: You are caring for Mr. Johnson, a 48-year-old newly diagnosed with Burkitt's lymphoma, 24 hours after his first cycle of high-dose chemotherapy. He complains of muscle cramps and tingling in his fingers. His vital signs are: BP 150/90, HR 112, RR 24. You note he has only produced 200 mL of urine in the last 8 hours.

Nursing Intervention Strategy: 1. Assessment: Immediately perform a focused assessment. Check for Chvostek's sign (tap facial nerve) and Trousseau's sign (inflate BP cuff) to assess for latent tetany from hypocalcemia. Attach continuous cardiac monitoring to assess for arrhythmias (prolonged QT interval, peaked T waves). Auscultate lung sounds (for fluid overload from hydration) and assess for jugular venous distension. 2. Action: Based on the lab results showing severe hypocalcemia, anticipate an order for IV calcium gluconate. Administer it slowly through a central line if possible (to avoid tissue necrosis from extravasation). Continuously monitor the ECG during infusion. Simultaneously, ensure the patient is on strict I&O and that IV hydration (e.g., D5 1/2NS with sodium bicarbonate) is running at the prescribed rate to promote diuresis. 3. Monitoring & Evaluation: Monitor serum calcium, potassium, phosphate, and uric acid levels every 4-6 hours. Assess urine output hourly; goal is >100-150 mL/hr. Watch for signs of improving calcium levels (decreased tingling, normal ECG) and worsening renal function (rising BUN/Creatinine).

Patient Safety and Precautions: * IV Calcium Administration: Administer slowly (per protocol, often over 10-30 minutes). Rapid infusion can cause bradycardia, hypotension, or cardiac arrest. Never mix with bicarbonate-containing solutions (causes precipitation). * Renal Protection: Avoid nephrotoxic drugs (e.g., NSAIDs, certain antibiotics). Ensure alkaline urine (pH >7) if ordered to increase uric acid solubility, but be cautious as this can promote calcium phosphate crystal formation if phosphate is high. * Hyperkalemia Precautions: Have emergency medications (calcium gluconate, insulin/glucose, albuterol) readily available. Restrict dietary potassium.

Nursing Procedure & Medication Flow Managing IV Calcium Gluconate: 1. Verify order and check for allergies. 2. Obtain baseline ECG and calcium level. 3. Use a central line or a large, patent peripheral IV. Assess site frequently. 4. Dilute as per pharmacy/guidelines. Administer via infusion pump at the prescribed slow rate. 5. Monitor vital signs and ECG continuously during infusion. Stop infusion for bradycardia or signs of extravasation. 6. Re-check serum calcium level after infusion as ordered.

Promoting Excretion & Preventing TLS: * Hydration: Goal 2-3 L/m²/day. Use IV fluids (often with sodium bicarbonate) as ordered. * Diuretics: May administer loop diuretics (e.g., furosemide) after adequate hydration is ensured to maintain urine output, but not initially. * Medications: * Allopurinol: Inhibits uric acid production. Give before and during chemo. * Rasburicase: Enzyme that breaks down existing uric acid. Rapidly lowers levels. Contraindicated in G6PD deficiency (causes hemolysis).

A Word from Your Senior Nurse "Tumor Lysis Syndrome is a perfect example of why nurses are the ultimate patient safety monitors. We see the subtle signs first — the tingling fingers, the muscle twitching, the slight change in urine output. In oncology nursing, you're not just giving chemo; you're managing the body's potentially violent reaction to it. When you see those lab values start to shift, think 'CRUSH' — Cardiac and Renal first. Your vigilant assessment and timely intervention can literally stop a patient from coding. On the NCLEX, they're testing this clinical judgment. In real life, you're using it to save a life."

핵심 개념

  • Tumor Lysis Syndrome — An oncologic emergency caused by the rapid release of intracellular contents (potassium, phosphate, nucleic acids) from lysed tumor cells into the bloodstream, leading to metabolic disturbances (hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia) and potential renal failure.
  • Hypocalcemia — A low serum calcium level (
  • Hyperkalemia — Elevated serum potassium level (>5.0 mEq/L). In TLS, it results from massive cell lysis. It is dangerous as it can cause life-threatening cardiac arrhythmias (e.g., peaked T waves, ventricular fibrillation).
  • Rasburicase — A recombinant urate-oxidase enzyme used to treat severe hyperuricemia in TLS. It rapidly converts uric acid to allantoin (which is more soluble). Contraindicated in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency due to risk of hemolytic anemia.
  • Chvostek's Sign — A clinical sign of latent tetany from hypocalcemia. Tapping the facial nerve just anterior to the ear causes twitching of the ipsilateral facial muscles (especially around the mouth). A positive sign indicates neuromuscular irritability.

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