The total iron content in the human body is approximately 3 to 4 grams. 70% of total iron is in the hemoglobin molecules in your red blood cells. These cells carry oxygen. So, your blood loses its oxygen-carrying capacity whenever you are iron deficient. Again, as most of the iron is in your red blood cells, anything causing blood loss will cause iron deficiency.
Iron storage
- Hemoglobin: ~2-2.5 g
- Storage Iron: ~0.5-1 g
- Myoglobin: ~0.3 g
- Enzymes and Other Proteins: ~0.1 g
- Plasma: Trace amounts
Causes of iron deficiency
- Menstrual Blood Loss: Heavy or prolonged periods (menorrhagia) are a leading cause of iron deficiency in women.
- Gastrointestinal Bleeding:
- Conditions like ulcers, hemorrhoids, or colorectal cancer.
- Chronic use of NSAIDs (e.g., ibuprofen, aspirin) can cause bleeding in the stomach.
- Frequent Blood Donations: Depletes iron stores.
- Poor Diet: Diets low in iron-rich foods (e.g., vegetarian/vegan diets without proper supplementation).
- Pregnancy and Lactation: Increased need for iron to support fetal growth, placenta development, and blood volume expansion.
- Anemia of Chronic Disease (ACD): Infections, autoimmune diseases, or kidney failure can disrupt iron metabolism.
- Helminthic infestation: They can cause bleeding in your gut, inflammation, and consumption of nutrients.
Symptoms of iron deficiency:
- Fatigue and Weakness – due to lack of oxygen-carrying capacity, your muscles and brain don’t get enough blood.
- Pale Skin and Mucous Membranes – due to loss of blood.
- Shortness of Breath – because of a lack of oxygen-carrying capacity, your lungs have to work more.
- Dizziness and Lightheadedness – because of lack of sufficient blood/ oxygen supply in your brain.
- Cold Hands and Feet – caused by lack of blood.
- Headaches – caused by lack of oxygen in the brain.
- Heart Palpitations – blood loss causes blood to become thinner, and your heart must do extra work to support your body.
- Brittle Nails and Hair Loss
- Dry skin
- Glossitis
- Cracks or Sores in the Mouth
- Pica – it means craving for inedible objects e.g. paper, tissue, vinegar, etc. It commonly happens in pregnant women due to iron deficiency during pregnancy. Pregnant women need more iron to support their fetus.
- Restless Legs Syndrome (RLS)
- Difficulty Concentrating and Irritability – due to lack of oxygen in the brain.
How much iron is required?
Infants and Children
- 0–6 months: 0.27 mg (adequate intake, generally met through breast milk or formula)
- 7–12 months: 11 mg
- 1–3 years: 7 mg
- 4–8 years: 10 mg
Adolescents
- Boys (9–13 years): 8 mg
- Boys (14–18 years): 11 mg (increased needs due to growth)
- Girls (9–13 years): 8 mg
- Girls (14–18 years): 15 mg (due to menstruation)
Adults
- Men (19+ years): 8 mg
- Women (19–50 years): 18 mg (to compensate for menstrual blood loss)
- Women (51+ years): 8 mg (post-menopause)
Pregnancy and Lactation
- Pregnant women: 27 mg (due to increased blood volume and needs of the growing fetus)
- Lactating women (18+ years): 9-10 mg
How do we diagnose iron deficiency?
- Serum Ferritin: If ferritin is <100 nanograms/mL then it may suggest iron deficiency. But ferritin is an acute phase reactant. Any infection/inflammation can cause ferritin to rise. So, it is not a very reliable marker of iron deficiency.
- Serum Iron: Total serum iron will be less than the normal limit in iron deficiency.
- Total Iron Binding Capacity (TIBC): TIBC increases in iron deficiency.
- Transferrin Saturation (Tsat): Tsat value <20% is strongly suggestive of iron deficiency.
- Peripheral Blood Smear: May show features of iron deficiency anemia, it may show small red blood cells (microcytes), low reticulocyte count, high red cell distribution width, pencil cells, etc.
What are iron-rich foods?
- Beef liver: ~6.5 mg per 3 oz (85 g)
- Lean ground beef: ~2.1 mg per 3 oz
- Chicken liver: ~11 mg per 3 oz
- Spinach: ~6.4 mg per cooked cup
- Pumpkin seeds: ~2.5 mg per ounce
It is good to eat vitamin C rich foods with iron-rich foods e.g. lemons, bell peppers, oranges, etc.
Medications
Iron supplements are available in the form of oral medications or intravenous infusions.
Oral formulations
- Ferrous Sulfate
- Ferrous Fumarate
- Ferrous Gluconate
- Ferric Citrate
- Polysaccharide-Iron Complex
- Heme Iron Polypeptide
- Carbonyl Iron
Intravenous formulations
Ferric derisomaltose (Monofer). Monofer is a medicine that is used to treat iron deficiency resulting in anemia when oral iron preparations are ineffective or cannot be used. This infusion replenishes the total iron reserve and can be given once a year or once six-monthly.
Selecting the right iron formulation
All iron formulations have their pros and cons. So your doctor will decide the best formulation for you based on your iron level, age, and comorbidities.
