Assessment of iron stores using ferritin and TSAT in CICs. Ferritin <30 μg/L in the presence of TSAT <45% is indicative of absolute low iron stores (black). Most patients with CICs in association with true ID are found to have TSAT<20% and ferritin <200 μg/L (red). Patients in the yellow region may be considered for iron supplementation if TSAT is 20% to 25% in CKD, or if TSAT is <20% and ferritin is up to 500 μg/L in HF, if they are receiving dialysis, and/or if they are using ESAs. Adequate iron stores are expected in the green areas, but caution is recommended for patients in the dark green area (TSAT >20% and ferritin >500 μg/L) if they are receiving parenteral iron, because they may be at risk of iatrogenic iron overload.