A nurse reviews a laboratory result of an adolescent female with a WBC count of 16,000/mm³ and increased immature neutrophils (bands) with normal monocytes. Which is the most appropriate interpretation?

• A. Acute infectious process
• B. Allergic reaction
• C. Neutropenia
• D. A resolving inflammatory process

Answer: (A)

A left shift in the neutrophil population signals an acute bacterial infection. When fighting bacteria, the bone marrow releases more neutrophils, including immature forms called bands. So a WBC count of 16,000 with an increased number of bands points to an acute infectious process rather than a viral illness or allergy. Allergic reactions more often raise eosinophils and don’t typically produce a banded neutrophil response; neutropenia would show a low WBC count; and a resolving inflammatory process would usually show the WBC count trending down with fewer bands as the infection subsides.