Which condition is primarily indicated by elevated white blood cells in a CBC?

Elevated white blood cell (WBC) counts in a complete blood count (CBC) are primarily indicative of an underlying condition that may involve the immune response, such as infection, inflammation, or malignancy. Among the options provided, leukemia is particularly associated with significantly increased WBC counts.

Leukemia is a type of cancer that originates in the blood and bone marrow, leading to the production of abnormal white blood cells. These abnormal cells proliferate uncontrollably and can accumulate in the blood, resulting in markedly elevated WBC levels. This is distinct from other conditions listed; for example, anemia generally presents with low red blood cell counts, while thrombocytopenia involves a reduction in platelet counts, and heart disease does not typically affect WBC levels directly.

Thus, when interpreting elevated white blood cell counts, leukemia stands out as the condition directly related to the abnormal proliferation of white blood cells. This specificity underscores the clinical importance of monitoring WBC levels in diagnosing hematological disorders.