From the Guidelines
Acute neutropenia without fever is primarily caused by medications, viral infections, autoimmune disorders, nutritional deficiencies, and bone marrow disorders, and management should focus on addressing the underlying cause and preventing infections. The causes of acute neutropenia without fever can be multifactorial, including:
- Medications such as chemotherapy, antibiotics like trimethoprim-sulfamethoxazole, and antipsychotics
- Viral infections
- Autoimmune disorders
- Nutritional deficiencies, including vitamin B12 and folate deficiencies
- Bone marrow disorders
Management of acute neutropenia without fever depends on the severity and underlying cause. For mild to moderate neutropenia (absolute neutrophil count 500-1500/mm³) without symptoms, close monitoring may be sufficient, as suggested by the American Society of Clinical Oncology growth factors expert panel 1. However, for severe neutropenia (ANC <500/mm³), more aggressive management may be necessary, including:
- Discontinuation of offending medications
- Treatment of underlying infections
- Granulocyte colony-stimulating factors (G-CSF) like filgrastim (Neupogen) at 5-10 μg/kg/day subcutaneously
- Preventive measures such as avoiding crowds and sick contacts, maintaining good hygiene, and consuming thoroughly cooked food
- Laboratory monitoring, including complete blood counts with differential every 2-3 days until neutrophil recovery
It is essential to understand the mechanism of neutropenia, which can be decreased neutrophil production, increased destruction, or abnormal margination in blood vessels, to guide appropriate treatment strategies. If neutropenia persists beyond 2-3 weeks despite addressing potential causes, bone marrow examination may be warranted to rule out primary hematologic disorders, as recommended by recent clinical practice guidelines 1.
From the FDA Drug Label
ZARXIO is a leukocyte growth factor indicated to • Decrease the incidence of infection‚ as manifested by febrile neutropenia‚ in patients with nonmyeloid malignancies receiving myelosuppressive anti‑cancer drugs associated with a significant incidence of severe neutropenia with fever (1. 1)
The following are indications that include neutropenia: • Reduce the duration of neutropenia and neutropenia-related clinical sequelae‚ e.g. ‚ febrile neutropenia, in patients with nonmyeloid malignancies undergoing myeloablative chemotherapy followed by bone marrow transplantation (BMT) (1.3) • Reduce the incidence and duration of sequelae of severe neutropenia (e.g. ‚ fever‚ infections‚ oropharyngeal ulcers) in symptomatic patients with congenital neutropenia‚ cyclic neutropenia‚ or idiopathic neutropenia (1.5)
The causes of acute neutropenia without fever are not directly addressed in the provided drug label. However, the label mentions several conditions associated with neutropenia, including:
- Nonmyeloid malignancies receiving myelosuppressive anti-cancer drugs
- Myeloablative chemotherapy followed by bone marrow transplantation
- Congenital neutropenia
- Cyclic neutropenia
- Idiopathic neutropenia
Management of acute neutropenia without fever is also not directly addressed, but the label provides dosage information for ZARXIO in various conditions associated with neutropenia 2.
From the Research
Causes of Acute Neutropenia without Fever
- Chemotherapy-induced neutropenia is a common cause of acute neutropenia without fever 3
- Neutropenia can occur due to various factors, including hematological malignancies, bone marrow failure, or as a side effect of certain medications 4
Management of Acute Neutropenia without Fever
- Filgrastim (G-CSF) is often used to treat neutropenia, especially in patients with severe neutropenia 3, 5
- Antibiotic prophylaxis may be considered in certain cases, such as in patients with a high risk of infection 6, 4
- The use of antimicrobial therapy, such as trimethoprim-sulfamethoxazole plus amikacin, may be effective in treating febrile neutropenic patients 7
Treatment Options
- Filgrastim alone or in combination with antibiotics may be used to treat neutropenia, depending on the severity of the condition and the presence of infection 6, 3
- Imipenem/cilastatin may be used as a second-line empirical therapy in cases where initial antibiotic treatment fails 7
- The choice of antibiotic regimen should be based on the patient's individual risk factors and the suspected source of infection 4