What laboratory findings are characteristic of anemia of chronic disease?

Anemia of chronic disease (ACD) is characterized by a complex interplay of inflammatory processes that affect iron metabolism. In ACD, the body often retains iron due to sequestration caused by cytokines released during chronic inflammation. This leads to a distinct laboratory profile: serum iron levels are decreased, indicating that there's reduced availability of iron for erythropoiesis, which is compounded by the body's impaired ability to utilize iron even when available.

Ferritin, on the other hand, is the primary iron-storage protein, and in the setting of ACD, it typically remains normal or can even be increased due to the body's response to inflammation. The body starts to store iron as a defense mechanism against infections and to limit its availability to pathogens, which results in increased ferritin levels. This is different from iron deficiency anemia, where both serum iron and ferritin would be low.

Total iron-binding capacity (TIBC) decreases in ACD, reflecting reduced transferrin levels caused by the inflammatory state. Therefore, a decreased serum iron level along with normal or increased ferritin is a hallmark finding in anemia of chronic disease, making the selected answer correct. This laboratory finding helps clinicians distinguish ACD from other types of anemia, particularly iron deficiency anemia.