# What is grade I/II/III/IV neutropenia?

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Neutropenia is a **reduced number of neutrophil granulocytes in the blood**. Normally, one would expect a number [latex]\geq 1500\ \frac{\text{neutrophils}}{\mu l}[/latex] in the peripheral blood, with a typical value of [latex]2500-4500 \frac{\text{neutrophils}}{\mu l}[/latex].
The decreased number of neutrophils is associated with reduced immune response and hence causes an increased chance of infection. Patients with neutropenia have a risk of developing **febrile neutropenia** (also known as **neutropenic sepsis**). Febrile neutropenia is a **medical emergency** and hence **requires immediate treatment**!

Neutropenia can be easily diagnosed using a *complete blood count* to count the number of neutrophils in the peripheral blood. In case a lab report does not contain the *absolute neutrophil count (ANC),*you can also multiply the *percentage of neutrophils* with the *leukocyte count*.

The different grades of neutropenia are defined in the **Common Terminology Criteria for Adverse Events (CTCAE).** On this page, we use *Version 5.0 published in 2017.*
**Grade 1 neutropenia**

is defined as an **absolute neutrophil count (ANC)** of

[latex display=“true”]\leq 1500\ \frac{\text{neutrophils}}{\mu l}[/latex] or equivalently [latex display=“true”]\leq 1500\ \frac{\text{neutrophils}}{mm³}[/latex] or equivalently [latex display=“true”]\leq 1.5\ billion\ \frac{\text{neutrophils}}{l}[/latex] or equivalently [latex display=“true”]\leq 1.5e9\ \frac{\text{neutrophils}}{l}[/latex]

**Grade 2 neutropenia**

is defined as an **absolute neutrophil count (ANC)** of

[latex display=“true”]1000\dotsb 1500\ \frac{\text{neutrophils}}{\mu l}[/latex] or equivalently [latex display=“true”]1000\dotsb 1500\ \frac{\text{neutrophils}}{mm³}[/latex] or equivalently [latex display=“true”]1000\ billion\ \dotsb 1500\ billion\ \frac{\text{neutrophils}}{l}[/latex] or equivalently [latex display=“true”]1e9\dotsb 1.5e9\ \frac{\text{neutrophils}}{l}[/latex]

**Grade 3 neutropenia**

is defined as an **absolute neutrophil count (ANC)** of

[latex display=“true”]500\dotsb 1000\ \frac{\text{neutrophils}}{\mu l}[/latex] or equivalently [latex display=“true”]500\dotsb 1000\ \frac{\text{neutrophils}}{mm³}[/latex] or equivalently [latex display=“true”]500\ billion\ \dotsb 1000\ billion\ \frac{\text{neutrophils}}{l}[/latex] or equivalently [latex display=“true”]0.5e9\dotsb 1e9\ \frac{\text{neutrophils}}{l}[/latex]

**Grade 4 neutropenia**

is defined as an **absolute neutrophil count (ANC)** of

[latex display=“true”]\leq 500\ \frac{\text{neutrophils}}{\mu l}[/latex] or equivalently [latex display=“true”]\leq 500\ \frac{\text{neutrophils}}{mm³}[/latex] or equivalently [latex display=“true”]\leq 500\ million\ \frac{\text{neutrophils}}{l}[/latex] or equivalently [latex display=“true”]\leq 0.5e9\ \frac{\text{neutrophils}}{l}[/latex]

**Grade 5 neutropenia**

is defined as death (like all *Grade 5 adverse events*).