Diagnosis and Prevalence of Iron Deficiency in the Critically Ill

Anemia and iron-restricted erythropoiesis in traumatic critical illness

“…39 Unfortunately, only sTfR and perhaps hepcidin can be used following blood transfusion, limiting the usefulness of these tests in most critically ill trauma patients. 20 …”

“…Inflammation and ID have opposite effects on hepcidin expression. 20,23 Lipopolysaccharides and IL-6 induce hepcidin synthesis, whereas TNF-> inhibits its synthesis. 24,25 Suppression of hepcidin during anemia or hypoxia seems to be an indirect effect dependent on increased EPO production and erythroid precursor expansion in the bone marrow.…”

“…Estimates vary between 9% and 38%. 19,20 Normal RBC turnover requires 25 mg of iron per day, which largely comes from iron recycling via hemophagocytosis and a small amount, 1 mg to 2 mg, via dietary iron intake. Phlebotomy alone is responsible for an average of 30-mL to 40-mL blood loss per day in critically ill patients, which amounts to daily iron losses of approximately 64 mg. 2 Absolute ID is present in approximately 1.3% of anemic critically ill trauma patients on admission.…”

“…Hence, ID anemia can still be present with ferritin values of 30 Kg/L to 100 Kg/L, in which case biomarkers such as C-reactive protein can help identify or exclude coexisting inflammation. 18,20,30 In the presence of inflammation, the lower limit of the normal range for ferritin is considered to be 100 Kg/L. 20…”