Many patients present to us with complaints of exertional dyspnea or tachycardia. Such patients may undergo extensive cardiovascular assessment, indicating an underlying sinister pathology for their symptoms. While this evaluation is justified, sometimes the underlying cause may not be so dangerous.
Iron deficiency, even before a full-fledged anemia develops may be the cause of such symptoms, which have been shown to improve on iron supplementation.
Iron deficiency (depleted iron stores in the body) and anemia are often perceived as interchangeable terms. While iron deficiency is the most common cause of anemia, but the two are different.
Deficiency of iron without anemia is much more prevalent than is detected. A person may have iron deficiency even if the hemoglobin is normal. The majority are unaware of their iron deficient state
Iron has a crucial role in oxidative metabolism within the mitochondria and production of hemoglobin and myoglobin (BMJ Open. 2018 Apr 5;8(4):e019240). Anemia due to iron deficiency impairs oxygen-carrying and tissue oxidative capacity, resulting in a diminished peak oxygen consumption (pVo2) and ability to endure submaximal exertion. Even in the absence of anemia, iron deficiency can attenuate exercise performance (J Am Coll Cardiol. 2008;51(2):103-12).
The FERRIC-HF trial, published in the Journal of the American College of Cardiology in 2008, which examined the effect of intravenous iron sucrose on exercise tolerance in anemic and nonanemic patients with symptomatic chronic heart failure and iron deficiency showed that IV iron supplementation improved exercise capacity and symptoms in patients with CHF and evidence of abnormal iron metabolism. Benefits were more evident in anemic patients.
If the patient has exertional breathlessness or symptoms such as fatigue, palpitations, headache or has a history of frequent absenteeism, also look for iron deficiency as a cause. Iron study, which measures serum iron, ferritin, transferrin, transferrin saturation, total iron-binding capacity should be done. Low serum ferritin is indicative of iron deficiency. Ferritin levels can be elevated by inflammatory processes and can mask iron deficiency (BMJ. 2017;357:j3175).
Iron supplementation, if iron deficiency found, improves functional capacity in these iron-deficient individuals even before anemia is corrected.