An Overview of Iron Deficiency Anemia

A common cause of anemia

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Iron deficiency anemia is among the most prevalent types of anemia. Symptoms include fatigue, pale skin, and tachycardia (rapid heart rate). This type of anemia can be caused by a variety of factors—most commonly low dietary iron or chronic bleeding. Some conditions, such as pregnancy, temporarily increase the risk of iron deficiency anemia.

Anemia is diagnosed based on a blood test, which may show small-sized red blood cells (RBCs) and possibly a decreased concentration of RBCs. The distinctive change in RBC structure is described as microcytic anemia

Treatments for iron deficiency anemia include dietary modification, iron supplements, Injectafer treatments, or blood transfusion. Because some health problems can lead to iron deficiency anemia, treatment for the underlying problem is often necessary, too.

iron deficiency anemia
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Typically, iron deficiency anemia causes nonspecific and vague symptoms, making it hard to recognize. Depending on the cause, it can develop gradually, with effects worsening over time.

Common symptoms of iron deficiency anemia include: 

Unexplained fatigue

  • Lack of energy
  • Sleepiness
  • Headaches
  • Feeling cold 
  • Dizziness or lightheadedness 
  • Pale skin
  • Reduced motivation
  • Depression
  • Tachycardia
  • A weak pulse 
  • Fainting
  • Pica (a craving for eating items that aren’t food, like dirt and ice) 
  • Glossitis (enlarged, swollen tongue)

You can experience all or some of these symptoms when you have iron deficiency anemia. And if you tend to develop recurrent iron deficiency, any of these signs can be an indication that low iron levels might be affecting your RBCs.

Associated Symptoms 

Sometimes iron deficiency anemia occurs along with other symptoms. For example, you may experience the effects of this type of anemia in association with heavy menstrual bleeding—during or shortly after your period.

Blood in the stool (which can appear bright red or dark and tarry) or blood in the urine (which can appear faintly pink or as clumps of blood) can also accompany or precede symptoms of iron deficiency anemia. 


People who are pregnant can be prone to iron deficiency anemia. While this can contribute to low energy during pregnancy, it can also cause complications that affect the baby, such as low birth weight or risk of prematurity.


You can have low iron levels due to inadequate iron in your diet, deficient iron absorption, or losing iron due to bleeding. Slow, persistent bleeding can cause iron deficiency anemia, and sudden rapid bleeding can cause it as well.

Low iron levels cause iron deficiency anemia. People who are pregnant and those who are breastfeeding generally require higher amounts of iron because of increased physical demand for iron during pregnancy and lactation.

Iron is an essential mineral that you can only get from your diet. You need iron because it is a component of heme, a protein that binds to and carries oxygen in RBCs. All of your cells need oxygen for energy, so low iron results in low energy. 

Normally, RBCs have a lifespan of approximately three to four months. As part of their normal life cycle, RBCs break down, and the iron can be stored and recycled as your body makes new RBCs.

You can have low iron levels due to inadequate iron in your diet, deficient iron absorption, or from losing iron as a result of bleeding. Slow, persistent bleeding can cause iron deficiency anemia, and sudden rapid bleeding can cause it as well. 

Insufficient Dietary Iron

Many types of food naturally contain iron, and some foods are fortified with the mineral. If you don’t eat enough iron-containing food, you could become deficient. 

Your recommended dietary allowance (RDA) of iron is based on your age, gender, and whether you are pregnant or breastfeeding. It is measured in milligrams (mg).

If your iron intake is below these recommended amounts, you are at a high risk of becoming iron deficient and developing iron deficiency anemia.

Recommended Daily Iron Intake
Age Male Female
under age 6 months 0.27 mg 0.27 mg
7-12 months 11 mg 11 mg
1-3 years old 7 mg 7 mg
4-8 years old 10 mg 10 mg
9-13 years old 8 mg 8 mg
14-18 years old 11 mg 15 mg
19-50 years old 8 mg 18 mg
Over age 51 8 mg 8 mg
Pregnancy N/A 27 mg
Lactation N/A 10 mg
*Recommended by the National Institutes of Health


A number of gastrointestinal (GI) issues can interfere with iron absorption. This mineral is normally absorbed in the duodenum, which is the first section of the small intestine. Illnesses that affect the stomach (which secretes enzymes into the small intestine) or the duodenum can prevent normal iron absorption.

Conditions such as Celiac disease, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and chronic diarrhea commonly cause nutrient malabsorption. 

Your diet can affect your iron absorption. Vitamin C, found in fruits and vegetables, enhances the absorption of iron. On the other hand, calcium, a mineral found in dairy products, inhibits iron absorption.


You can lose your iron stores due to bleeding. Typically, your body responds to blood loss by making new RBCs. But the process can take weeks, and some RBCs that your body produces may lack sufficient iron if you haven’t replenished your supply yet.

Health problems that can cause chronic bleeding include stomach ulcers, intestinal polyps, colon cancer, hemorrhoids, and chronic urinary tract infections. 

Menstrual bleeding can also result in low iron, as can severe blood loss due to a traumatic injury. 


The most definitive way of diagnosing iron deficiency anemia is with a blood test that evaluates your RBC quantity and size. Iron deficiency anemia is described as microcytic anemia because it is characterized by red blood cells that are smaller than normal RBCs. This can be identified with a complete blood count (CBC).

If you have signs of iron deficiency anemia, you might also need to have tests that measure your iron levels. And you might also need an evaluation to look for diseases and identify bleeding that could be the root cause of your iron deficiency anemia.

RBC Measures

Your CBC will include a report that details several RBC characteristics.

  • RBC count: This is the number of RBCs seen in a sample of blood, and it is reported based on a standard mcL sample. It is measured in millions per microliter (mcL). The normal RBC range is 4.1 to 5.1 million/mcL for women and 4.5 to 5.9 million/mcL for men. The standard RBC count for children is 4.0 to 5.5 million/mcL. Your RBC count can be low or normal with iron deficiency anemia.
  • Hematocrit: This test measures the volume of RBCs in a blood sample, which takes into account the size and the quantity. A normal hematocrit is 41.5% to 50.4% for men and 35.9% to 44.6% for women. This value is expected to be lower in iron deficiency anemia.
  • Mean corpuscular volume (MCV): This value is a measure of the average size of your RBCs. A normal MCV is 80 to 96 femtoliters (or cubic micrometers) per cell. A low MCV is often indicative of iron deficiency anemia.
  • Red cell distribution width (RDW): This value reflects the variation in size of your RBCs. Normal RDW is 11.8% to 15.6 %. If you have iron deficiency anemia, your RDW would be increased because you would have a wider range in the size of your RBCs.

Iron Tests

Sometimes, with iron deficiency anemia, your iron and iron carrying capacity is measured as well. These are not standard diagnostic tests, but measurements of iron levels may be necessary if it is unclear whether you are iron deficient.

Iron tests include:

  • Serum iron: This test measures the total amount of iron in your blood. In iron-deficiency anemia, the result may be less than 10 micromoles per liter (mmol/L).
  • Serum ferritin: Ferritin is a protein that binds to and stores iron. References values for ferritin are 20 to 200 micrograms per liter (mcg/L) for women and 40 to 300 mcg/L for men. This value is a reflection of your body’s ability to store iron. In iron deficiency anemia, these values may be less than 10 mcg/L. Low ferritin is an indication of iron deficiency, but you can have iron deficiency with normal ferritin.
  • Serum transferrin: Transferrin is a protein that transports iron through the bloodstream. Transferrin rises when iron levels are low, so an elevated serum transferrin is a reflection of low iron.
  • Transferrin saturation: The percentage of transferrin that is bound to iron should be approximately 25% to 35%. Low saturation values mean that less transferrin is bound to iron, which suggests iron deficiency.

Sources of Bleeding

If your iron level is low, your medical team may order tests to identify a source of bleeding, especially if your RBC count and/or hematocrit are also low. A stool or urine sample may be sent to a laboratory to be examined for evidence of blood. Imaging tests may identify bleeding polyps or tumors. 

Further tests can include invasive diagnostic examination of your GI system or bladder. 

  • Colonoscopy: This is the most common test used to look for the source of GI bleeding. It is a procedure in which a camera-equipped flexible tube is placed into the rectum and moved into the colon so the inner lining can be visualized. This test can identify lesions in the colon, such as ulcers, polyps, and cancer. If your healthcare provider is concerned about a lesion, a biopsy may be obtained during your colonoscopy.
  • Endoscopy: An endoscopy is a diagnostic examination in which a camera-equipped tube is placed into the mouth and advanced for visualization of the esophagus and portions of the stomach. 
  • Cystoscopy: Generally, the urinary tract is not commonly the source of an extensive volume of bleeding. But if there is a concern that a lesion of the urethra or bladder could be the cause of your iron deficiency anemia, your medical team may need to evaluate these structures with a cystoscopy, an invasive test in which a small tube is placed into the urethra and bladder. 
  • Pelvic examination: Regularly scheduled pelvic examinations are often recommended for routine screening of gynecological health. However, with iron deficiency anemia, your healthcare provider may do a pelvic examination to look for a source of bleeding. 


Iron deficiency anemia is treated in several different ways. If your diet is the root of your iron deficiency, you may be able to see improvement by eating iron-rich foods and/or taking an iron supplement. Iron-rich foods include red meat, seafood, poultry, beans, vegetables, fruit, and enriched grains.

Iron supplements, Injectafer infusion, and blood transfusion are other options if your iron deficiency is severe.

Iron Supplements

Iron supplements are available in oral pill or tablet form, and as an oral suspension. These supplements are available over-the-counter (OTC) and as prescription formulations. It is important to ask your healthcare provider how to take these supplements as the timing of certain foods and medications can inhibit or increase its absorption.

Keep in mind that iron can cause severe constipation, so you should check with your healthcare provider before taking iron supplements—even if you plan to take an OTC strength formulation.

Injectafer Treatment 

Injectafer (ferric carboxymaltose injection) is an iron replacement treatment approved for the treatment of iron deficiency anemia in adults who do not improve or who can’t tolerate oral iron supplements. This treatment is also approved for treatment of iron deficiency anemia for adults who have non-dialysis dependent chronic kidney disease.

Each mL of Injectafer contains 50 milligrams (mg) of elemental iron. It is given by two infusions, usually separated by seven days. The recommended dose for people who weigh more than 110 pounds is 750 mg of Injactefer per infusion for a total cumulative dose not to exceed 1,500 mg of iron per course. For adults who weigh less than 110 pounds, each infusion is 15 mg/kg body weight, for a total cumulative dose not to exceed 1,500 mg of iron per course.

Blood Transfusion 

If you are actively bleeding or if iron supplements and medication would not adequately correct your iron deficiency in a timely manner, you may need to have a blood transfusion. This process involves an infusion of blood into your vein. Most of the time, a blood transfusion for treatment of iron deficiency anemia uses donor blood that is screened for disease and typed to verify that it matches your blood.

In rare instances—such as if your medical team anticipated that you could develop iron deficiency anemia due to blood loss associated with a major procedure—an autologous blood transfusion may be possible. This involves an infusion of your own blood if it was collected and stored before you experienced blood loss. You can donate your own blood for an autologous transfusion up to approximately one month before your procedure and no closer to your procedure than 72 hours. 

A Word From Verywell

Iron deficiency anemia is not uncommon, and the World Health Organization considers it a global health concern. Because many of the symptoms are so vague, it’s hard to recognize, and you might blame your symptoms on lifestyle factors like working too hard or just not getting enough sleep.

It can be hard to know for sure if iron deficiency anemia is at the root of your condition, but you should get medical attention if you aren’t feeling your best. Usually, simple blood tests can identify iron deficiency anemia, but you may need further evaluation to pinpoint the cause of your mineral deficiency. 

Treatment of your anemia should improve your symptoms. And you also need treatment for your underlying condition so that you won’t be as likely to develop iron deficiency again.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Deloughery TG. Iron deficiency anemia. Med Clin North Am. 2017;101(2):319-332. doi:10.1016/j.mcna.2016.09.004

  2. National Heart, Lung, and Blood Institute. Iron-deficiency anemia.

  3. Centers for Disease Control and Prevention. Iron.

  4. National Institutes of Health. Iron.

  5. American Association for Clinical Chemistry. Complete blood count (CBC).

  6. American Association for Clinical Chemistry. Transferrin and iron-binding capacity (TIBC, UIBC).

  7. Food and Drug Administration. Injectafer Label.

  8. American Red Cross. Frequently asked questions about blood donation.

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.