TF and nutritional disorder: A large positive correlation was observed between absolute iron deficiency and dyspnea severity (r<sup>2</sup> = 0.949, p = 0.026). Statistically significant differences were found in hemoglobin (anemia), serum iron, serum ferritin, total iron-binding capacity, and transferrin saturation between iron-deficient and iron-replete patients (p < 0.05).