Low Hemoglobin and Iron Deficiency: Causes and Consequences

Low hemoglobin levels typically indicate iron deficiency, the most common cause of anemia worldwide. Hemoglobin, an iron-containing protein in red blood cells, binds oxygen in the lungs and delivers it to tissues.

Pathophysiology

Iron is essential for heme synthesis. When iron stores are depleted (due to inadequate intake, malabsorption, chronic blood loss, or increased demand), hemoglobin production falls, reducing oxygen-carrying capacity. This leads to tissue hypoxia and the classic symptoms of anemia: fatigue, pallor, dyspnea on exertion, tachycardia, and cognitive impairment.

Common Causes

• Menstrual blood loss, pregnancy
• Gastrointestinal bleeding (ulcers, tumors, NSAID use)
• Dietary insufficiency (vegan/vegetarian diets without supplementation)
• Malabsorption (celiac disease, H. pylori, bariatric surgery)
• Increased demand (growth spurts, pregnancy)

Diagnosis and Management

Confirm with CBC, serum ferritin, transferrin saturation, and peripheral smear. Treatment involves oral or IV iron replacement and addressing the underlying cause.