Neutropenia in Pediatric Practice

George B. Segel, MD* 2. Jill S. Halterman, MD, MPH† 1. *Professor, Department of Pediatrics, Division of Hematology Oncology 2. †Associate Professor of Pediatrics, Division of General Pediatrics, University of Rochester School of Medicine & Dentistry, Rochester, NY After completing this article, readers should be able to: 1. Describe when a patient has true neutropenia, understanding the variation with age and ethnic background. 2. Know the relative risk of infection at various values of the absolute neutrophil count. 3. Discuss the differences between inherited and acquired causes of neutropenia. 4. List the initial studies to evaluate patients who have neutropenia. The significance of neutropenia is a common query to hematology specialists from primary care physicians. Severe neutropenia is defined as an absolute neutrophil count (ANC) of fewer than 500/mcL (0.5×109/L) and is a common and expected complication of chemotherapy for childhood neoplasms. This article considers those patients who have neutropenia unrelated to chemotherapy toxicity. This type of neutropenia may be noted when a complete blood count (CBC) is performed in a sick newborn, a febrile child, a child taking chronic medication, or as part of a routine evaluation. Severe hereditary conditions such as Kostmann syndrome and certain immunodeficiency syndromes associated with neutropenia are rare, perhaps 1 per 100,000, and are more likely to present in neonates and infants, although acquired conditions such as immune neutropenia and neutropenia related to infection also occur in this age group. A mild-to-moderate decrease in the ANC (percent neutrophils times the total white count) frequently is seen in viral illness or related to medication use as well as in some healthy persons of African ancestry. A number of inherited conditions associated with neutropenia are associated with other congenital anomalies such as dysplastic thumbs in Fanconi anemia, albinism in Chediak-Higashi syndrome, and dwarfism in the cartilage hair or Shwachman-Diamond syndromes. A CBC is not ordered routinely for well children examined in the pediatrician's office or when children present with common febrile illnesses such as upper respiratory tract infections or otitis media. A CBC is warranted if …