Has the patient had any recent illnesses?
The usual response to an infection is an increase in neutrophil count. However, certain bacterial, rickettsial, parasitic, and viral infections can result in neutropenia (see TABLE 823,27-29). Viral infections may cause transient neutropenia because of either bone marrow suppression or increased peripheral destruction, while neutropenia related to an overwhelming bacterial infection results from the depletion of bone marrow reserves.23,27
Do you suspect a nutritional deficiency?
Patients with a nutritional deficiency of B12, folate, or copper are likely to exhibit a deficiency in more than just neutrophils.23,27 In developed countries, people with neutropenia may have a history of malnutrition due to a disease (eg, anorexia nervosa) or surgery (eg, gastric bypass) that causes severe calorie restriction.20
Does your patient have symptoms of a connective tissue disease?
Neutropenia, in association with arthralgias, joint swelling, splenomegaly, or rash may be a manifestation of an underlying collagen vascular disorder, such as rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE).20 If the clinical scenario supports one of these diagnoses, undertake or refer the patient for a rheumatologic evaluation. This may include studies of anti-cyclic citrullinated peptide antibodies, rheumatoid factor to evaluate for RA, and/or antinuclear antibodies to evaluate for SLE.30,31 While most neutropenias associated with autoimmune disease are mild, neutropenia associated with Felty syndrome (RA, splenomegaly, and neutropenia) may be severe (ANC <100 cells/mcL).20,23
Is the etiology unclear?
Patients with moderate to severe neutropenia without an apparent etiology, in the setting of aplastic anemia, or in the presence of splenomegaly and/or lymphadenopathy, should undergo a hematologic evaluation and/or bone marrow biopsy, given that hematologic malignancy is a potential cause.20,27
The treatment of neutropenia hinges on correctly identifying the etiology of the diminished neutrophil count. If the cause is a medication, infection, underlying rheumatologic condition, or nutritional deficiency, then either treating the entity or withdrawing the offending medication should result in resolution of the neutropenia. If the cause is determined to be familial or ethnic, then patient reassurance is all that is required.
CORRESPONDENCE
Richard W. Temple, MD, FAAFP, CDR MC USN, Camp Lejeune Family Medicine Residency, Naval Medical Center Camp Lejeune, 100 Brewster Blvd, Camp Lejeune, NC 28547-2538; richard.w.temple2.mil@mail.mil.