From the Guidelines
Elevated Absolute Neutrophil Count (ANC) in an infant is most commonly caused by bacterial infections, inflammation, or physiologic stress, and less commonly by hematologic disorders or congenital conditions, as reported in recent studies 1. When evaluating an elevated ANC in an infant, it is crucial to consider the clinical context, including the presence of fever, irritability, poor feeding, or other signs of infection. The infant's age is also an essential factor, as normal ranges vary during different stages of infancy.
Common Causes of Elevated ANC in Infants
- Bacterial infections, such as pneumonia, meningitis, urinary tract infections, and sepsis, which trigger the bone marrow to produce more neutrophils to fight the infection 1.
- Inflammation from non-infectious conditions, such as tissue injury, burns, or autoimmune disorders, can also increase neutrophil counts.
- Certain medications, particularly corticosteroids and epinephrine, stimulate neutrophil release from bone marrow storage pools.
- Physiologic stress, including birth trauma, crying, pain, and seizures, can temporarily elevate neutrophil counts through the release of catecholamines.
Less Common Causes of Elevated ANC in Infants
- Hematologic disorders, such as leukemia, particularly chronic myeloid leukemia, can cause persistent neutrophilia.
- Congenital disorders, such as Down syndrome, may be associated with higher neutrophil counts.
- Normal newborns often experience a physiologic neutrophilia in the first 24 hours of life as a response to the stress of birth, with counts typically normalizing within a few days. It is essential to note that some congenital disorders, such as severe congenital neutropenia (SCN) and Shwachman–Diamond syndrome (SDS), can also affect neutrophil counts, although these conditions are rare and typically present with neutropenia rather than neutrophilia 1. In the context of real-life clinical medicine, it is crucial to prioritize the evaluation of bacterial infections and other acute conditions that may require prompt treatment, while also considering the possibility of underlying hematologic or congenital disorders.
From the Research
Causes of Elevated Absolute Neutrophil Count (ANC) in Infants
Elevated ANC in infants can be caused by various factors, including:
- Infections, such as neonatal sepsis or serious bacterial infections 2, 3
- Inflammatory conditions, which can stimulate the production of neutrophils 4
- Immature neutrophils, which can be elevated in young febrile infants 5
Infections as a Cause of Elevated ANC
Infections, particularly those caused by bacteria, can lead to an increase in ANC. This is because the body produces more neutrophils to fight off the infection. Studies have shown that ANC, along with other parameters such as C-reactive protein (CRP) and immature to total neutrophil ratio (I/T ratio), can be useful in diagnosing neonatal sepsis and serious bacterial infections 2, 3.
Other Causes of Elevated ANC
Other causes of elevated ANC in infants include:
- Neoplastic diseases, which can affect the production of neutrophils 6
- Morphologic changes in neutrophils, such as toxic granulation, vacuolation, and Dohle bodies, which can indicate bacterial infections 4
- Age-related factors, as band count has been shown to have greater sensitivity in infants and elderly patients 4
Diagnostic Value of ANC
The diagnostic value of ANC in predicting bacterial infections has been studied, and results show that ANC can be a useful marker, particularly when used in combination with other parameters such as CRP and I/T ratio 2, 3. However, the accuracy of ANC in detecting invasive bacterial infections can vary, and guidelines without these parameters may be better for risk assessment 5.