What is the role of iron deficiency in the diagnosis of anemia of chronic disease and renal failure?

Updated: Nov 27, 2018
  • Author: Edgar V Lerma, MD, FACP, FASN, FAHA, FASH, FNLA, FNKF; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Answer

As noted above, iron deficiency is the most common identifiable cause of ESA resistance. The 2 most important tests to order to assess iron deficiency are transferrin saturation and serum ferritin.

The importance of these tests lie in the fact that even the diagnosis of iron deficiency anemia is not truly straightforward. In anemia of chronic kidney disease, there is primarily an imbalance between the iron required for erythropoiesis versus the amount released by the reticuloendothelial tissues. This is referred to as functional iron deficiency, which is characterized by a transferrin saturation (TSAT) less than 20% and a ferritin level less than 100 ng/mL.

However, clinicians must be aware that ferritin is an acute phase reactant that can be elevated in states of chronic infection or inflammation. Therefore, an elevated ferritin does not necessarily imply iron store adequacy or overload. Current guidelines recommend against use of iron products when ferritin is 500 ng/mL or greater.


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