# Situation: A nurse works in the pediatric rehabilitation clinic and the emergency room of a regional hospital. A 4-year-old with newly diagnosed acute lymphoblastic (lymphocytic) leukemia and a very high white cell count started induction chemotherapy, including asparaginase, 24 hours ago. The nurse reviews: Potassium: 6.3 mmol/L Phosphate: high Calcium: 7.0 mg/dL (1.75 mmol/L) Uric acid: high Urine output: falling over the last 6 hours Which complication do these findings MOST suggest?

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> subject: Nursing Practice II — Maternal and Child Health Nursing

## 문제

Situation: A nurse works in the pediatric rehabilitation clinic and the emergency room of a regional hospital.

A 4-year-old with newly diagnosed acute lymphoblastic (lymphocytic) leukemia and a very high white cell count started induction chemotherapy, including asparaginase, 24 hours ago. The nurse reviews:
Potassium: 6.3 mmol/L
Phosphate: high
Calcium: 7.0 mg/dL (1.75 mmol/L)
Uric acid: high
Urine output: falling over the last 6 hours
Which complication do these findings MOST suggest?

## 보기

1. Leukostasis from the high cell count
2. Acute pancreatitis from asparaginase
3. Tumor lysis syndrome **✔ 정답**
4. Dehydration from poor oral intake

**정답: 3**

## 해설

Rapid breakdown of leukemic cells at the start of therapy releases potassium, phosphate, and uric acid; phosphate binds calcium, causing secondary hypocalcemia, and the crystals injure the kidneys. This pattern with falling urine output is tumor lysis syndrome, most common in leukemia with a high white cell count. Pancreatitis can lower calcium but does not raise potassium, phosphate, and uric acid together.

## 심화 해설

Clinical picture A 4-year-old with newly diagnosed acute lymphoblastic leukemia (ALL), a very high white cell count, and induction chemotherapy started 24 hours ago now shows a pattern of hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia, and falling urine output. This combination points to a metabolic emergency rather than an isolated organ problem.

Why the findings fit tumor lysis syndrome Rapid breakdown of leukemic blasts releases intracellular potassium, phosphate, and nucleic acids into the circulation. Nucleic acids are metabolized to uric acid, so serum uric acid rises. The released phosphate binds calcium, which lowers ionized and total calcium. Hyperkalemia, hyperphosphatemia, hyperuricemia, and secondary hypocalcemia occurring together after chemotherapy is the classic biochemical signature of tumor lysis syndrome (TLS). Uric acid and calcium phosphate crystals can then deposit in renal tubules, causing acute kidney injury and reduced urine output. TLS is defined by the presence of two or more of these metabolic abnormalities, and this child has all four plus declining renal function [1][4].

Why the other options do not explain the full picture Leukostasis from a high white cell count can cause respiratory or neurologic symptoms from sludging of blasts in small vessels, but it does not produce the combined electrolyte and uric acid pattern seen here. Acute pancreatitis from asparaginase can lower calcium through fat saponification, but it would not simultaneously raise potassium, phosphate, and uric acid. Dehydration from poor oral intake may reduce urine output, but it would not create hyperphosphatemia with hypocalcemia and hyperuricemia.

| Finding | Mechanism in TLS | Clinical consequence |
| --- | --- | --- |
| Hyperkalemia | Release of intracellular potassium from lysed blasts | Risk of arrhythmia, cardiac arrest |
| Hyperphosphatemia | Release of intracellular phosphate | Binds calcium, promotes crystal deposition |
| Hypocalcemia | Phosphate binding of calcium | Tetany, seizures, prolonged QT |
| Hyperuricemia | Nucleic acid breakdown to uric acid | Uric acid crystal nephropathy |
| Falling urine output | Renal tubular obstruction by crystals | Acute kidney injury, worsening electrolyte abnormalities |

Pediatric ALL context ALL is one of the malignancies most strongly associated with TLS because of its high tumor burden and rapid cell turnover [4]. Children with a very high white cell count at diagnosis are at especially high risk, and TLS typically occurs early after induction chemotherapy begins . In a study of 91 children with ALL, TLS was a common complication characterized by the same biochemical abnormalities described in this scenario [1]. Another cohort of 5537 children with ALL identified TLS as a serious early complication, reinforcing the need for close monitoring in the first 24 to 72 hours of therapy .

Nursing priority The immediate nursing focus is prevention of life-threatening arrhythmias from hyperkalemia and protection of renal function through aggressive hydration and uric acid reduction. Watch out! Hypocalcemia in TLS is usually secondary to hyperphosphatemia; correcting calcium without first lowering phosphate can worsen calcium phosphate crystal deposition in tissues. Key point! Falling urine output in a child with ALL after starting chemotherapy is a red flag for TLS-related acute kidney injury, not simply dehydration, and requires urgent laboratory and renal monitoring [1][4].References (research sources)

- [1]Tumor lysis syndrome in pediatric acute lymphoblastic leukemia at tertiary care center.Research articleNaeem B, Moorani KN, Anjum M, Imam U (2019) · DOI: 10.12669/pjms.35.4.715

- [4]Tumor lysis syndrome.Research articleRajendran A, Bansal D, Marwaha RK, Singhi SC (2013) · DOI: 10.1007/s12098-012-0824-7

## 임상 시나리오

Tumor Lysis Syndrome RecognitionPost-induction metabolic emergency in high-burden ALL
After starting induction chemotherapy for high-count ALL, monitor for the classic TLS tetrad: hyperkalemia, hyperphosphatemia, secondary hypocalcemia, and hyperuricemia. Falling urine output signals evolving acute kidney injury from crystal deposition.

TLS is defined by two or more metabolic abnormalities; this child has all four plus declining renal function. Potassium 6.3 mmol/L and calcium 7.0 mg/dL require urgent intervention.

CautionDo not attribute the full picture to asparaginase-induced pancreatitis or leukostasis; those do not raise potassium, phosphate, and uric acid together. Early recognition and aggressive hydration plus urate-lowering therapy are critical.

## 핵심 개념

- **Tumor lysis syndrome** — Metabolic emergency from rapid cancer cell breakdown releasing potassium, phosphate, and nucleic acids, causing hyperkalemia, hyperphosphatemia, secondary hypocalcemia, hyperuricemia, and acute kidney injury.
- **Secondary hypocalcemia** — Low serum calcium resulting from phosphate binding calcium, common in tumor lysis syndrome.
- **Hyperuricemia** — Elevated uric acid from nucleic acid catabolism, which can crystallize in renal tubules and worsen kidney injury.
- **Acute kidney injury** — Rapid decline in renal function, here caused by uric acid and calcium phosphate crystal deposition in tubules.
- **Asparaginase** — Chemotherapy agent used in ALL induction that can cause pancreatitis and hypocalcemia but not the full TLS metabolic pattern.

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