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Iron deficiency anemia

Definition

Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are many types and causes of anemia.

Iron deficiency anemia occurs when your body does not have enough iron. Iron helps make red blood cells. Iron deficiency anemia is the most common form of anemia.

Reticulocytes
In the presence of some anemias, the body increases production of red blood cells (RBCs), and sends these cells into the bloodstream before they are mature. These slightly immature cells are called reticulocytes, and are characterized by a network of filaments and granules. Reticulocytes normally make up 1% of the total RBC count, but may exceed levels of 4% when compensating for anemia.

Alternative Names

Anemia - iron deficiency

Causes

Patient Education Video: Iron deficiency anemia

Red blood cells bring oxygen to your body's tissues. Red blood cells are made in your bone marrow. Red blood cells circulate through your body for 3 to 4 months. Parts of your body, such as your spleen, remove old blood cells.

Iron is a key part of red blood cells. Without iron to make hemoglobin, your blood cannot carry oxygen effectively. Your body normally gets iron through your diet. It also reuses iron from old red blood cells.

Iron deficiency anemia develops when your body's iron stores run low. This can occur because:

  • You lose more blood cells and iron than your body can replace
  • Your body does not absorb iron well
  • Your body is able to absorb iron, but you are not eating enough foods that contain iron
  • Your body needs more iron than normal (such as if you are pregnant or breastfeeding)

Bleeding can cause iron loss. Common causes of bleeding are:

  • Heavy, long, or frequent menstrual periods
  • Cancer in the esophagus, stomach, small bowel, or colon
  • Esophageal varices, often from cirrhosis
  • The use of aspirin, ibuprofen, or medicines that may thin the blood for a long time, which can cause gastrointestinal bleeding
  • Peptic ulcer disease

Your body may not absorb enough iron in your diet due to:

  • Celiac disease
  • Crohn disease
  • Gastric bypass surgery
  • Taking too many antacids or too much of the antibiotic tetracycline

You may not get enough iron in your diet if:

  • You are a strict vegetarian
  • You do not eat enough foods that contain iron

Symptoms

You may have no symptoms if the anemia is mild.

Most of the time, symptoms are mild at first and develop slowly. Symptoms may include:

  • Feeling weak or tired more often than usual, or with exercise
  • Headaches
  • Dizziness
  • Palpitations
  • Problems concentrating or thinking

As the anemia gets worse, symptoms may include:

  • Brittle nails
  • Blue color to the whites of the eye
  • Desire to eat ice or other non-food things (pica)
  • Feeling lightheaded when you stand up
  • Pale skin color
  • Shortness of breath
  • Sore or inflamed tongue
  • Mouth ulcers
  • Uncontrolled movement of legs (during sleep)
  • Hair loss

Symptoms of the conditions associated with bleeding that cause iron deficiency anemia include:

  • Dark, tar-colored stools or blood in the stool
  • Heavy menstrual bleeding
  • Pain in the upper belly (from ulcers)

Exams and Tests

To diagnose anemia, your health care provider may order these blood tests:

  • Complete blood count (CBC)
  • Reticulocyte count
Hypochromia
A decrease in the amount of hemoglobin found in red blood cells is called hypochromia.

To check iron levels, your provider may order:

  • Serum iron level
  • Total iron binding capacity (TIBC) in the blood
  • Serum ferritin
  • Bone marrow biopsy (if the diagnosis is not clear)

To check for causes of blood loss, your provider may order:

  • Colonoscopy
  • Fecal occult blood test
  • Upper endoscopy
  • Tests to detect sources of blood loss in the urinary tract or uterus

Treatment

Treatment may include taking iron supplements and eating iron-rich foods.

Iron supplements (most often ferrous sulfate) build up the iron stores in your body. Most of the time, your provider will measure your iron level before you start supplements.

If you cannot take iron by mouth, you may need to take it through a vein (intravenous) or by an injection into the muscle.

Pregnant and breastfeeding women will need to take extra iron because they often cannot get enough iron from their normal diet.

Often your anemia will improve or resolve with 6 weeks of iron therapy. You will need to keep taking iron for another 6 months to replace your body's iron stores in your bone marrow.

Iron supplements are mostly well tolerated, but may cause:

  • Nausea
  • Vomiting
  • Constipation

Iron-rich foods include:

  • Chicken and turkey
  • Dried lentils, peas, and beans
  • Fish
  • Meats (liver is the highest source)
  • Soybeans, baked beans, chickpeas
  • Whole-grain bread

Other sources include:

  • Oatmeal
  • Raisins, prunes, apricots, and peanuts
  • Spinach, kale, and other greens

Vitamin C helps your body to absorb iron. Good sources of vitamin C are:

  • Oranges
  • Grapefruits
  • Kiwi
  • Strawberries
  • Broccoli
  • Tomatoes

Outlook (Prognosis)

With treatment, the outcome is likely to be good, but it does depend on the cause.

When to Contact a Medical Professional

Contact your provider if:

  • You have symptoms of iron deficiency
  • You notice blood or a black tar-appearance in your stool

Prevention

A balanced diet should include enough iron. Food sources of iron are listed above. If advised by your provider, take iron supplements.

Gallery

Reticulocytes
In the presence of some anemias, the body increases production of red blood cells (RBCs), and sends these cells into the bloodstream before they are mature. These slightly immature cells are called reticulocytes, and are characterized by a network of filaments and granules. Reticulocytes normally make up 1% of the total RBC count, but may exceed levels of 4% when compensating for anemia.
Blood cells
Blood is comprised of red blood cells, platelets, and various white blood cells.
Hypochromia
A decrease in the amount of hemoglobin found in red blood cells is called hypochromia.

References

Camaschella C. Disorders of iron homeostasis: iron deficiency and overload. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 37.

Elghetany MT, Banki K. Erythrocytic disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 33.

Means RT Jr. Approach to the anemias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 144.

National Heart, Lung, and Blood Institute website. Iron-deficiency anemia. www.nhlbi.nih.gov/health/anemia/iron-deficiency-anemia. Updated March 24, 2022. Accessed February 1, 2024.

Last reviewed April 18, 2023 by John Roberts, MD, Professor of Internal Medicine (Medical Oncology), Yale Cancer Center, New Haven, CT. He is board certified in Internal Medicine, Medical Oncology, Pediatrics, Hospice and Palliative Medicine. Review provided by VeriMed Healthcare Network. Internal review and update on 02/03/2024 by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team..

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