Impaired iron transport (IIT) is a form of iron deficiency (ID) defined as transferrin saturation (TSAT) < 20% irrespective of serum ferritin levels. It is frequently observed in heart failure (HF) where it negatively affects prognosis irrespective of anaemia.
Reference: Is red distribution width a valid tool to predict impaired iron transport in heart failure?
Campodonico J, Carulli E, Doni F, Russo GL, Junod D, Gaudenzi Asinelli M, Bonomi A, De Martino F, Vignati C, Pezzuto B, Agostoni P. Front Cardiovasc Med. 2023 Apr 11;10:1133233.