The anemia of chronic disease: Spectrum of associated diseases in a series of unselected hospitalized patients

Abstract

Previous studies of the anemia of chronic disease (ACD) have generally begun with patients afflicted with one of the classical underlying diseases such as rheumatoid arthritis. The clinical spectrum of ACD has not been thoroughly examined. We hypothesized that many patients have an anemia with the characteristics of ACD but do not have one of the infectious, inflammatory, or neoplastic disorders usually associated with ACD. We therefore evaluated a series of consecutive, unselected, anemic patients admitted to a county hospital. All patients admitted to the medicine ward service of a county hospital were screened for anemia (hematocrit less than 40% in men, less than 37% in women). Additional laboratory data were collected on all anemic patients, except those with active gastrointestinal bleeding, hemolytic disease, or leukemia or multiple myeloma. The patients were divided into three groups on the basis of serum values indicating iron distribution: iron deficiency (serum ferritin less than 10 ng/mL), ACD (serum iron less than 60 micrograms/dL and serum ferritin more than 50 ng/mL), and all others (non-ACD). The hospital records of the patients in the latter two groups were reviewed and their diagnoses recorded. Seven patients with iron deficiency were not considered further. Ninety patients with ACD were compared with 75 patients with non-ACD. The anemia in ACD patients was more severe than most authors describe. The mean hematocrit was 31%, and 20% of patients had hematocrits below 25%. The anemia was usually normocytic (mean red cell volume [MCV] 86 fL), but 21% had an MCV less than 80 fL. The level of saturation of serum iron-binding capacity was quite low in ACD (mean 15%) and was normal in non-ACD (mean 31%). Renal insufficiency was common in both groups; serum creatinine values were more than 2 mg/dL in 31% of patients with ACD and 20% of non-ACD patients. Sixty percent of patients with ACD had a principal diagnosis that fell into the infectious, inflammatory, and neoplastic categories commonly associated with ACD. Renal insufficiency was the major diagnosis in 16%, and the principal diagnosis in 24% was a disease not commonly considered to be associated with ACD. In non-ACD patients, the principal diagnosis was an infectious, inflammatory, or neoplastic disease in 55%, renal insufficiency in 9%, and another disease in 36%. When ACD was defined by the abnormalities of iron distribution, which are its most consistent and widely accepted characteristics, the spectrum of associated diseases was much broader than the traditional categories of infectious, inflammatory, and neoplastic disorders, and the overlap with non-ACD was large. Until the etiologic and pathogenetic mechanisms of ACD are better understood, a flexible and inclusive view of this disorder seems appropriate.