What Is Iron Deficiency?

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Iron deficiency is the most common cause of nutritional deficiency in the world. It usually stems from a lack of dietary iron, but medical illnesses like gastrointestinal (GI) disorders, as well as pregnancy and menstruation, can cause iron deficiency as well. It can cause subtle, slowly worsening effects, such as anemia (low red blood cell count) and learning delays in children.

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Iron Deficiency Symptoms

Iron is a mineral that forms the heme portion of hemoglobin, a protein inside red blood cells (RBCs) that binds to oxygen. Low iron levels can impair oxygen delivery throughout your body.

In doing so, iron deficiency causes a variety of symptoms, typically due to the anemia. Common symptoms include:

Many people do not get medically evaluated for these symptoms, often ignoring them or attributing them to something else. But it is important to see your healthcare provider if you are feeling run down, lacking in energy, or are prone to feeling cold.

There are a number of other symptoms that can develop as a result of iron deficiency, including:

  • Headaches or migraines
  • Lightheadedness
  • Trouble concentrating
  • Moodiness and irritability
  • Pica, a craving for eating ice or non-food items, such as metal or dirt
  • Generalized weakness
  • A rapid heart rate
  • Shortness of breath
  • Restless legs when trying to sleep
  • Infections
  • Glossitis, an inflamed, red, tongue
  • Dry hair and/or nails

The exact reason why iron deficiency causes some of its effects—such as glossitis and pica—is not completely clear.

Iron deficiency can affect you differently depending on your age and health. For example, it can affect the development of a growing baby born to a woman who was iron deficient during pregnancy. It can cause learning problems when it affects children, and it is more likely to cause shortness of breath if you have heart failure or pulmonary disease.


Iron deficiency can affect anyone at any age. There are some risk factors that can make you more prone to developing iron deficiency, such as:

  • Menstruation, due to blood loss
  • Pregnancy: There is an increased need for nutrients such as iron.
  • Chronic bleeding: Conditions such a gastrointestinal (GI) ulcer or cancer can cause significant blood loss.
  • Malnutrition (low iron supply due to one's diet); this can also occur in vegetarians
  • Malabsorption: In this case, trouble absorbing iron (due to a GI illness), even if you consume enough in your diet
  • Gastric bypass surgery, which can cause malabsorption

Athletes at all levels of training and ability are at risk of iron deficiency. High physical demands and restrictive diets contribute to iron deficiency, and factors such as altitude training and exercise-induced hormonal influences may play a role as well. Research suggests that 5% to 10% of male athletes and 15% to 35% of female athletes have iron deficiency.


If you note fatigue and other symptoms of iron deficiency, your healthcare provider may consider this nutritional deficiency as the root cause.

Iron deficiency is not usually detected based on a physical examination. Many of the signs, such as a rapid heart rate and dry hair, occur at a relatively late stage and can be caused by other medical problems as well. Some people may have pale fingers or toes, but this occurs with a number of other medical conditions too.

Rather, blood tests are the most common method of identifying iron deficiency.

Blood Tests

A complete blood count (CBC) is a fairly common screening test that measures your RBC count, the size and shape of your RBCs, and your hemoglobin. A CBC also measures your white blood cells (WBCs), which can be a reflection of some illnesses that cause iron deficiency (such as lymphoma and leukemia).

Iron deficiency is associated with a low or normal concentration of RBCs. Normal RBC count reference ranges are:

  • 4.2 to 5.4 million/mcL for women
  • 4.7 to 6.1 million/mcL for men
  • 4.1 to 5.5 million/mcL for children

Microscopic examination of the RBCs can assess their shape and size. The RBCs can be either normal or small in size when you have an iron deficiency, and they may appear pale.

With iron deficiency, you may have a low hemoglobin concentration. Normal hemoglobin test reference ranges are:

  • 12.0 to 15.5 gm/dl for women
  • 13.5 to 17.5 gm/dl for men
  • 11 to 16 g/dl for children
  • 11 to 12 g/dl for pregnant women

RBC and hemoglobin abnormalities suggest iron deficiency, and having more than one of these abnormalities is highly suggestive (though not proof) of low iron.

A measurement of your iron levels is the only thing that can confirm that your iron is low. Iron tests are not standard, but you may have this test if your CBC doesn't clarify whether your iron level is low or not, or if you are not improving with standard treatment.

A normal iron level ranges from 15 to 30 ug/L, but this value should be assessed based on a number of factors. For example, pregnant women should have an iron level closer to 30 ug/L.

Interventional Tests

You may need to have one or more interventional diagnostic tests to evaluate the cause of your iron deficiency. Since GI bleeding is a fairly common cause of iron deficiency, a digital rectal examination, colonoscopy, or endoscopy may be necessary. A rectal examination can identify bleeding, and colonoscopy or endoscopy can find where it is coming from.

Your CBC may show WBC alterations suggestive of lymphoma or leukemia. If there is a high chance that you could have one of these conditions, you may need to have a bone marrow biopsy, which can assess the shape and appearance of your WBCs.


If you have iron deficiency, you will need prompt treatment. In most cases, iron level can be brought up slowly with dietary changes. Supplements may be helpful, but should only be used if advised by your healthcare provider, as they can cause side effects.

In cases when more rapid restoration of healthy iron levels is necessary, intravenous (IV) iron replacement may be necessary.

Additionally, if an illness has caused your iron deficiency, you will need treatment for that illness. Iron deficiency anemia may require treatment with a blood transfusion to restore RBC count.

Dietary Sources of Iron

Meat contains heme iron, which is easier for the body to absorb, meaning you get more of the iron from these foods. But there are other sources of iron you can consider as well.

Consider these options as you plan what to eat:

  • Meat: Beef, chicken, lamb, pork, and turkey
  • Shellfish: Shrimp, clams, and oysters, in particular, contain the same heme iron as meat.
  • Tofu: Avoid options with added calcium, as this can decrease iron absorption. It's best to get calcium from other sources.
  • Beans: For example, pinto, black, lentils, and kidney beans
  • Certain vegetables: Leafy vegetables, green beans, and sun-dried tomatoes are good sources. Broccoli and bok choy also contain vitamin C, which helps your body absorb iron from your diet.
  • Certain fruit: Dried apricots, peaches, prunes, and raisins contain iron. Options rich in vitamin C (oranges, lemons, limes, watermelon, kiwi) can help with absorption, but only if eaten at the same time as iron-rich foods.
  • Nuts: Cashews, hazelnuts, pistachios, and almonds
  • Pumpkin seeds: Raw pumpkin seeds, also called pepitas, are a great plant source of iron. If you are going to roast them, avoid excessive heat because that can decrease the amount of iron in them. Consider using them as a salad topping.
  • Breads and cereals: In the United States and other countries, flours are fortified with vitamins and minerals including iron. You can identify these products by looking for enriched flour on the ingredient list. Fortified foods include bread, cereal, pasta, and other grains. In general, cereals with bran in them have more iron than others cereals.

Calcium in dairy products can interfere with your ability to absorb iron. So if you don't eat much red meat, it is a good idea not to consume meat and dairy in the same meal.

Dietary Supplements

It is generally advised to avoid iron supplements unless they are prescribed by a healthcare provider. If you need to take iron supplements, be sure to take them at the recommended dose, and only for the weeks or months that your healthcare provider recommends.

Prenatal vitamins contain iron because pregnant women need more than normal amounts. Iron supplements can cause uncomfortable constipation, so be sure to talk to your healthcare provider about how you can safely manage your constipation, especially if you are pregnant.

Iron toxicity results in liver failure, heart failure, arthritis, and a number of other serious problems. If you have a medical illness (such as cancer or liver failure), you could have difficulty metabolizing nutrients like iron, making you more prone to toxicity.

Medical or Surgical Intervention

You may need more serious intervention for iron deficiency. Sometimes, iron deficiency is extreme, or excessive blood loss can be a major problem.

If you can't consume food or supplements by mouth or if your body can't absorb iron due to malabsorption, then you will need an intramuscular (IM) injection or IV supplementation.

A blood transfusion may be necessary if you are severely anemic. And surgical repair of a bleeding polyp, ulcer, or cancerous lesion is often necessary to manage a harmful disease and to stop blood loss.

A Word From Verywell

Iron deficiency is a fairly common cause of low energy. You can usually prevent and reverse iron deficiency by consuming iron in your diet. However, if you have a medical cause of your low iron, be sure to follow up on your treatment, because diet alone will not solve the problem.

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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.
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Additional Reading

By Amber Yates, MD
Amber Yates, MD, is a board-certified pediatric hematologist and a practicing physician at Baylor College of Medicine.