From the Guidelines
High white blood cell counts in infants are most commonly caused by infections, and a thorough medical evaluation is necessary to determine the underlying cause and provide appropriate treatment. The causes of high white blood cell counts in infants can be varied, including bacterial infections such as pneumonia, urinary tract infections, or meningitis, which trigger the immune system to produce more white blood cells to fight the pathogens 1. Viral infections can also cause elevated counts, though sometimes they may initially decrease white blood cells before rising. Other causes include inflammation from conditions like inflammatory bowel disease, certain medications such as steroids or epinephrine, leukemia or other bone marrow disorders, and some congenital conditions. Normal physiologic stress, including birth trauma, crying, or pain, can temporarily raise white blood cell counts in newborns.
Some key points to consider when evaluating high white blood cell counts in infants include:
- The total white blood cell count and differential may provide suggestion of a bacterial etiology when viral or parasitic etiologies are also being considered 1
- A high total white blood cell count and neutrophil count often occur in patients with certain infections, such as STEC O157 infections who subsequently develop HUS 1
- Monocyte predominance may suggest the presence of an intracellular pathogen such as Salmonella 1
- Leukemia, such as chronic myeloid leukemia, can also cause high white blood cell counts in infants, and diagnosis typically involves physical examination, additional blood tests, and possibly cultures or imaging studies 1
It is essential to seek medical attention if an infant shows signs of illness alongside abnormal blood test results, as prompt diagnosis and treatment are crucial, especially for infections. Treatment depends entirely on identifying and addressing the specific cause rather than treating the elevated count itself. A recent study published in 2023 provides guidance on the management of children and adolescents with chronic myeloid leukemia in blast phase, highlighting the importance of accurate diagnosis and timely treatment 1. Another study published in 2017 provides guidelines for the diagnosis, treatment, and follow-up of chronic myeloid leukemia, emphasizing the need for regular monitoring and adjustment of treatment as needed 1.
From the Research
Causes of High White Blood Cells in Infants
- Infections or inflammatory processes are the most common causes of leukocytosis, which is a common laboratory finding 2
- Physical stress, emotional stress, and certain medications such as corticosteroids, lithium, and beta agonists can also elevate white blood cell counts 2
- Primary bone marrow disorders, such as acute leukemias, chronic leukemias, and myeloproliferative disorders, can cause extremely elevated white blood cell counts 2
- Leukocytosis can also be a predictor of non-infective mortality and morbidity, particularly due to cardiovascular or cerebrovascular causes 3
- In pediatric patients, infections are the most common cause of leukocytosis or leukopenia, and symptoms such as persistent fevers, weight loss, bruising, fatigue, and adenopathy may suggest more serious etiologies 4
Clinical Features and Outcome
- Patients with unexplained or persistent leukocytosis may appear to be in a state of continued inflammation, recently described as the persistent inflammation-immunosuppression and catabolism syndrome (PICS) 5
- These patients may have a prolonged hospital course, extensive use of empiric broad-spectrum antibiotics, and increased risk of colonization with resistant opportunistic organisms 5
- Elevated leukocyte count can be a harbinger of systemic inflammation, disease progression, and poor prognosis, particularly in older adults 6
Diagnostic Considerations
- Age-specific laboratory values should be used when interpreting results in pediatric patients 4
- A peak white blood cell count above 100,000 per mm3 (100 x 10(9) per L) represents a medical emergency due to the risk of brain infarction and hemorrhage 2
- Patients with extremely elevated white blood cell counts or concurrent abnormalities in red blood cell or platelet counts should be suspected of having primary bone marrow disorders 2