Anemia of Chronic Disease - Anemia of Inflammation

Iron indices are complicated in the face of inflammation, and may be further confounded by concomitant anemia of chronic disease/anemia of inflammation (ACD/AI) and iron deficiency anemia (IDA). In both ACD/AI and IDA, insufficient functional iron is available for erythropoiesis. In IDA, mean corpuscular volume (MCV) is often (although not always) reduced, whereas MCV is usually normal in ACD/AI. Similarly, cells are often hypochromic in IDA, whereas they are frequently normochromic in ACD/AI.  Total iron binding capacity (TIBC) and soluble transferrin receptor levels are increased in IDA, but normal or decreased in ACD/AI. Both serum iron and transferrin saturation (Tsat) are decreased in both IDA and ACD/AI. ^, ,  See Laboratory Testing to Distinguish Between ACD/AI and IDA table, below.

Anemia of chronic disease/anemia of inflammation (ACD/AI) is a common complication in many conditions that affect iron status, including inflammatory bowel disease (IBD) and chronic kidney disease (CKD). IBD leads to problems in iron and vitamin absorption, and thus may result in ACD/AI with concomitant iron deficiency anemia and megaloblastic anemia. Normocytic anemia is also frequently observed in CKD. Anemia in CKD results primarily from decreased erythropoiesis, and may be exacerbated by hemolysis, iron deficiency, hemorrhage, medication toxicity, chronic infections, and other factors ; patients with CKD may therefore demonstrate simultaneous ACD/AI and iron deficiency. Regular anemia workups are recommended for both patient populations. For more information on laboratory testing for anemia in patients with IBD or CKD, see the Iron Deficiency Anemia topic.

Anemia of critical illness can be severe and develops rapidly, often within a few hours or days,  resulting in a limited time frame for testing. Although further study is required, this rapid onset of anemia may result from reduced red blood cell production and survival,  as well as iatrogenic factors such as blood loss due to phlebotomy and medication.  Anemia of critical illness is treated via transfusion; to determine which patients require transfusion, a hemoglobin threshold of 70 g/L is recommended.  In patients with some conditions (eg, sepsis, traumatic brain injury, and cardiovascular disease), a higher hemoglobin threshold to trigger transfusion may be appropriate. 

Anemia is a risk factor for morbidity, mortality, and other unfavorable outcomes in patients ≥65 years of age.  The prevalence of anemia in older adults increases with age, exceeding 20% in patients ≥85 years of age.  Given the potential for adverse outcomes, the evaluation of anemia in elderly adults is especially important if surgery or other procedures that may result in blood loss are planned. Furthermore, anemia in older adults is often associated with an underlying chronic condition, and iron indices may not be typical of younger adults.  Some experts recommend assessing iron status via serum ferritin or transferrin saturation (Tsat) tests following a finding of low hemoglobin. In patients who are iron deficient, consider evaluation for gastrointestinal malignancy and oral iron supplementation. In patients with replete iron stores, testing for chronic kidney disease (CKD) and vitamin deficiency is recommended, as well as assessment for other chronic or inflammatory conditions.