# Situation: A 34-year-old man is admitted with newly diagnosed acute myeloid leukemia (AML). His white blood cell count is 45,000/mm³ with 70% blasts, his hemoglobin is 8.2 g/dL (82 g/L), and his platelet count is 15,000/mm³. Induction chemotherapy is planned. His wife asks why he keeps getting infections when his white blood cell count is so high. Which explanation is accurate?

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> subject: Nursing Practice III — Care of Clients with Problems in Surgery, Oxygenation, Fluid and Electrolytes, Infectious, Inflammatory and Immunologic Response, Cellular Aberrations

## 문제

Situation: A 34-year-old man is admitted with newly diagnosed acute myeloid leukemia (AML). His white blood cell count is 45,000/mm³ with 70% blasts, his hemoglobin is 8.2 g/dL (82 g/L), and his platelet count is 15,000/mm³. Induction chemotherapy is planned.

His wife asks why he keeps getting infections when his white blood cell count is so high. Which explanation is accurate?

## 보기

1. His spleen traps the white cells before they reach the tissues
2. His high white cell count uses up the antibodies in his blood
3. The leukemia cells attack and destroy his normal white cells
4. Most of his white cells are immature and cannot fight germs **✔ 정답**

**정답: 4**

## 해설

In acute leukemia, malignant precursors (blasts) multiply in the marrow and spill into the blood, so the total count may be high. Blasts are immature and do not function as neutrophils, and they crowd out normal marrow cells. The result is functional neutropenia, with infection as the leading cause of death.

## 심화 해설

Why a high WBC count does not mean better infection defense in AML

In acute myeloid leukemia, the bone marrow is overtaken by malignant precursor cells called blasts. These blasts multiply rapidly and spill into the peripheral blood, which is why the total white blood cell count can appear dramatically elevated—here, 45,000/mm³ with 70% blasts. However, the key point is that blasts are functionally useless for fighting infection because they are immature cells that have not developed into working neutrophils.

The absolute neutrophil count (ANC), not the total WBC count, determines the patient’s real capacity to combat bacteria and fungi. In this patient, the marrow is so crowded with leukemic blasts that normal hematopoietic precursors are suppressed—a phenomenon often described as “crowding out.” As a result, the production of mature, segmented neutrophils falls dramatically. The patient therefore has functional neutropenia despite a high total white count, because the vast majority of circulating white cells are blasts that cannot phagocytose, generate respiratory burst, or migrate to sites of infection.

Watch out! Do not equate a high total WBC count with immune competence. In acute leukemia, the total count can be misleadingly high while the ANC is critically low. The infection risk tracks with the ANC, not the total WBC.

Key point! Infection is the leading cause of death in acute leukemia, driven by functional neutropenia from blast crowding and impaired normal marrow production.

The distinction between total WBC count and functional neutrophil capacity is central to understanding why this patient “keeps getting infections.” Neutropenia is defined by a reduction in the absolute number of circulating neutrophils, and when it arises from an underlying hematologic malignancy such as AML, the risk of infectious complications is substantial [1]. In leukemia, malignant hematopoiesis disrupts normal immune effector cell production, and intensive chemotherapy further depletes functional neutrophils, compounding the infection risk [3]. The disruption of normal hematopoietic homeostasis in leukemia also alters host-microbiome interactions, which can impair barrier function and shift immune responses in ways that further increase susceptibility to infection .

| Parameter | This patient | Clinical meaning |
| --- | --- | --- |
| Total WBC count | 45,000/mm³ | High due to circulating blasts; not protective |
| Blast percentage | 70% | Immature, nonfunctional leukemic cells |
| Functional neutrophils (ANC) | Critically low (not directly given) | Determines true infection risk |
| Hemoglobin | 8.2 g/dL (82 g/L) | Anemia from marrow crowding |
| Platelets | 15,000/mm³ | Severe thrombocytopenia; bleeding risk |

The other answer choices do not explain the recurrent infections. The spleen does not selectively trap white cells before they reach tissues in AML. Antibodies are not “used up” by a high white cell count. And while leukemic blasts do crowd out normal marrow cells, they do not directly attack and destroy mature neutrophils in the circulation—the problem is failed production of functional cells, not active destruction of normal white cells. The accurate explanation is that most of the circulating white cells are immature blasts that cannot fight germs, leaving the patient functionally neutropenic and highly vulnerable to infection.References (research sources)

- [1]How to approach neutropenia.Research articleBoxer LA (2012) · DOI: 10.1182/asheducation-2012.1.174

- [3]Therapeutic ecology of the fiber-microbiota-barrier axis in leukemia: resilience, immune recovery and pharmacomicrobiomics.Research articleXie R, Jing X. (2026) · DOI: 10.3389/fmicb.2026.1913406

## 임상 시나리오

AML High WBC Does Not Mean Immune ProtectionFunctional neutropenia drives infection risk
In acute myeloid leukemia, the total WBC count may be high because blasts spill into the blood, but these cells are immature and cannot fight germs. The patient’s real defense depends on the absolute neutrophil count (ANC), not the total WBC.

Leukemic blasts crowd out normal marrow precursors, causing functional neutropenia even when the total WBC is elevated. This is why infection is the leading cause of death in acute leukemia.

CautionNever equate a high total WBC count with immune competence in acute leukemia. Always assess the ANC and treat fever promptly as a sign of possible neutropenic infection.

## 핵심 개념

- **Blasts** — Immature leukemic precursor cells that multiply in the marrow and spill into blood; they are functionally useless for fighting infection.
- **Functional neutropenia** — A state of inadequate neutrophil function despite a normal or high total WBC count, caused by replacement of normal cells with nonfunctional blasts.
- **Absolute neutrophil count (ANC)** — The number of mature neutrophils available to fight infection; a more reliable indicator of infection risk than total WBC count.
- **Crowding out** — Suppression of normal hematopoietic precursors in the bone marrow due to massive proliferation of leukemic blasts.
- **Induction chemotherapy** — Initial intensive treatment aimed at achieving remission in acute leukemia by eliminating leukemic blasts.

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