USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Corticosteroids are known to influence the white blood cell (WBC) count in a particular manner, which is key to understanding the correct answer. The use of corticosteroids leads to neutrophilia, meaning an increase in neutrophils, while also causing eosinopenia (a decrease in eosinophils) and lymphopenia (a decrease in lymphocytes).

In this case, multiple myeloma is characterized by the impact of corticosteroids on blood cells. The neutrophils' increase occurs due to the steroid's effects on the bone marrow and their ability to mobilize neutrophils from the marginal pool into the circulation. Conversely, corticosteroids suppress lymphocyte production and function, which contributes to lymphopenia. Eosinophils are also reduced because corticosteroids inhibit their release from the bone marrow and decrease their recruitment to tissues.

Other conditions listed do not consistently demonstrate this specific pattern with corticosteroids. For instance, polycythemia vera is primarily related to increased red blood cell production without the specific WBC changes caused by corticosteroids. HIV typically leads to lymphopenia but does not have a direct relationship with neutrophils and eosinophils in the same way steroids do. Sepsis, while often