Iron deficiency anemia laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.D. [2]

Iron studies are conducted if microcytic hypochromic anemia is found on complete blood count and peripheral blood film. Iron studies are helpful in making the diagnosis of iron deficiency anemia, with serum ferritin levels being the most widely used test.

• Complete blood count- Hb <10.5mg/dl and MCV <95fL^[1][2][3][4].
• Microcytic and hypochromic anemia on peripheral blood film.
• Red cell distribution width increased.
• Reticulocyte count is low.
• Iron studies:
  • Iron stain (prussian blue staining) of erythroid precursors (sideroblasts) on marrow spicules shows lack of stainable iron in erythroid precursors.
  • Serum ferritin levels < 30ng/ml, and serum ferritin <41 ng/mL in a patient with anemia and comorbidities (chronic diseases/inflammation)
  • Serum iron <60 mcg/dL.
  • Total iron binding capacity/ serum transferrin- TIBC is calculated by multiplying serum transferrin by 1.389. It is increased in iron deficiency anemia and decreased in anemia of chronic disease. TIBC>350 to 400 mcg/dL is diagnostic of iron deficiency.
  • Transferrin saturation (TSAT) is the ratio of serum iron to TIBC: (serum iron  ÷  TIBC  x  100). It is <15% in iron deficiency (normal is 25-40%).
• Elevated erythrocyte (RBC) zinc protoporphyrin (eg, >80 mcg/dL).
• Decreased iron stain on eryhtroid precursors.

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