Absolute Neutrophil Count (ANC)
Frequently used to assess neutropenic fever in chemotherapy patients.
Advice
- Neutropenic fever (without a source of infection found) is typically the result of direct toxic effects of chemotherapy on mucosal surfaces and the immune system in addition to the impact of the underlying malignancy. It is defined as a single oral temperature of 38.3ºC (101ºF) or a temperature of greater than 38.0ºC (100.4ºF) sustained for more than 1 hour in a patient with neutropenia. It is typically seen in those who have received anti-cancer therapies in the last 6 weeks. Filgrastim (Neupogen), a.k.a. G-CSF, can stimulate production of neutrophils, but is rarely indicated in the evaluation and treatment of neutropenic fever.
- Additional tools to risk stratify a neutropenic fever patient and predict complications include the Clinical Index of Stable Febrile Neutropenia (CISNE) and Multinational Association for Supportive Care in Cancer (MASCC) Score.
Management
- Obtain a complete blood count with differential.
- ANC is calculated as 10 x WBC count in 1000s x (% PMNs + % bands).
- Classify neutropenia as mild, moderate, or severe as in Evidence.
- ANC values can also be interpreted by NCI risk categories:
| NCI Risk Category | ANC |
|---|---|
| 0 | Within normal limits |
| 1 | ≥1,500 to <2,000 cells/mm3 |
| 2 | ≥1,000 to <1,500 cells/mm3 |
| 3 | ≥500 to <1,000 cells/mm3 |
| 4 | <500 cells/mm3 |
Critical Actions
If the clinical scenario is suggestive of neutropenic fever, appropriate cultures and infectious disease workup should be instituted along with prompt initiation of empiric broad-spectrum antibiotics to cover mostly endogenous flora.