Iron deficiency anemia

What iron deficiency anemia is

Iron is the mineral that holds hemoglobin, the protein in red blood cells that picks up oxygen in the lungs and carries it to all tissues. The body gets iron from food (about 1–2 mg is absorbed each day) and cannot make it; it stores it as ferritin, mainly in the liver and bone marrow, and loses small amounts every day. When the stores run out, ferritin falls first and hemoglobin falls later: then the tissues receive less oxygen and the heart has to work harder.

Anemia is diagnosed when hemoglobin is below about 13 g/dl in men, 12 g/dl in women and 11 g/dl in pregnancy. But iron deficiency begins before anemia: ferritin can be low with hemoglobin still normal, and symptoms such as fatigue can appear already at this stage.

The key point: iron deficiency is a symptom, not a final diagnosis. It says that iron is being lost or not absorbed, and the doctor has to look for why.

Symptoms

• fatigue and weakness, often noticeable during work or exercise;
• pallor of the skin, lips and the inside of the eyelids;
• shortness of breath and palpitations on exertion;
• headache, dizziness, poor concentration, cold hands and feet;
• hair loss, brittle or spoon-shaped nails, a sore or smooth tongue, cracks at the corners of the mouth;
• cravings to eat ice or non-food items (pica), restless legs syndrome;
• in women, heavy periods.

At first symptoms are mild and people call it “normal tiredness.” In severe anemia or in people with heart disease, iron deficiency can worsen shortness of breath and chest pain.

Causes

Iron is missing because it is lost, does not get in or is not absorbed, or because needs are greater. The main causes are:

• Blood loss, the most common cause in adults: heavy periods in women and hidden loss from the digestive tract. Possible sources are stomach ulcer (see peptic ulcer), gastritis, Helicobacter pylori, hemorrhoids, polyps and tumors of the colon or stomach, as well as frequent use of anti-inflammatory drugs or aspirin.
• Inadequate intake from food: diets very low in meat or iron-rich foods, especially in vegetarians who do not compensate, and in children and older people.
• Poor absorption: celiac disease, atrophic gastritis, stomach or small-bowel surgery (for example gastric bypass), inflammatory bowel disease and some medicines that lower stomach acid for a long time.
• Increased needs: pregnancy and breastfeeding, growth in children and adolescents, frequent blood donation.

Diagnosis

The first test is the complete blood count, which shows low hemoglobin, small red cells (low MCV) and uneven cell size (high RDW). The diagnosis is then confirmed by low ferritin, a marker of iron stores, and by serum iron, binding capacity and transferrin saturation. Ferritin is reliable when it is low; in practice, if it is borderline and there is inflammation or chronic disease, the doctor interprets the result in context, because ferritin rises with inflammation. If the blood count is low but ferritin is normal, other causes are sought (vitamin B12, folic acid, chronic disease, thyroid or kidney disease).

Looking for the cause is the decisive part of the assessment:

• in premenopausal women, menstrual history is often the explanation; still, if periods are not heavy, or if the anemia does not improve, a digestive cause is also sought;
• in men and postmenopausal women, iron deficiency always calls for assessment of the digestive tract, because it often comes from hidden blood loss: gastroscopy for the esophagus, stomach and duodenum, and colonoscopy for the colon; as well as tests for celiac disease and H. pylori;
• stool tests for hidden blood, as indicated.

Treatment

Treatment has two goals that must not be separated: replenishing iron and treating the cause. If iron alone is given without looking for the cause, the anemia improves temporarily but a serious disease may be hidden.

Oral iron. This is the first treatment in most cases. One tablet a day or, as your doctor advises, one tablet every other day (which often absorbs better and is better tolerated). It is taken on an empty stomach or with a little food if it causes upset, ideally with orange juice or vitamin C, which helps absorption, and away from tea, coffee, milk and calcium. Common side effects are constipation, nausea and dark stools. Note: dark stool from iron is common and harmless, but melena (black, sticky, very foul-smelling stool) is a sign of bleeding and needs urgent care.

Hemoglobin should rise 1–2 g/dl within 2–4 weeks; the doctor checks the test after about a month. Treatment continues for about 3 months after hemoglobin normalizes, to fill the stores (ferritin), so often 3–6 months in total. Then the blood count and ferritin are checked some months later, and after that every 6 months to a year if the cause may return, or sooner when the doctor considers it reasonable. Keep iron tablets away from children: an overdose is very dangerous.

Intravenous iron. It is used when oral iron is not tolerated or not absorbed (celiac disease, stomach surgery, inflammatory bowel disease), when losses continue, when rapid replenishment is needed (severe anemia, close to surgery, late pregnancy), or in kidney and heart disease. Blood transfusion is reserved for severe anemia with symptoms or risk.

Diet. It helps but rarely solves the problem alone: heme iron, the most absorbable, is found in red meat, liver and fish; non-heme iron in legumes, leafy green vegetables and grains; absorption rises with vitamin C (citrus, peppers) and falls with tea and coffee near a meal. The cause is treated specifically: an ulcer with medicines, heavy periods with the gynecologist, celiac disease with a gluten-free diet.

When to see a doctor

• fatigue and pallor that do not pass;
• low hemoglobin or low ferritin on tests;
• very heavy periods or bleeding that recurs;
• shortness of breath or palpitations with light effort;
• immediately: melena (dark, sticky stool), blood in the stool or in vomit.

This information is educational and does not replace a medical visit. Do not take iron on your own for a long time without tests, because too much iron can be harmful.