Below is the snapshot of Anemia of Chronic Disease from PATHOMA
PATHOMA says about the anemia of chronic disease under its laboratory findings that there is decreased percentage saturation. Why would the percentage saturation decrease? As in if there is anemia, this means that there is lack of Hemoglobin, so whatever little bit of hemoglobin there is a lot of oxygen should bind to it resulting in increased % saturation. Isn’t it?
%saturation is talking about the percentage of transferrin bounded to iron. Your serum iron and TIBC all decreases so your %saturation will be decreases as well as serum iron decrease more than transferrin
Anemia of chronic diseases means that body is trying to hide iron from chronic disease, otherwise has normal iron levels. Transferin saturation is a percentage of serum iron over TIBC. TIBC should be normal or low in anemic of chronic diseases. If we divide low serum iron by normal TIBC, it will come out as low.