An Overview of Iron Deficiency

Iron rich foods can prevent iron deficiency
Eising / Getty Images

Iron deficiency can occur for a number of reasons, from related medical conditions to blood loss to diet choices. If the case is severe, untreated, and/or prolonged, iron-deficiency anemia—a decrease in the quantity, size, and function of the red blood cells—can result, having several notable consequences. At a minimum, low iron levels can make you feel tired and weak, impact your concentration, and cause dry skin and nails. But it can also cause heart palpitations, shortness of breath, increased risk for infections, and more.

Iron and Your Body

Iron is necessary for producing hemoglobin and myoglobin, two proteins that carry oxygen in your blood. When you don't have enough iron in your system, this important function is hampered, denying your cells what they require to give you the energy you need. This is iron deficiency anemia.

It takes a while to develop symptoms of iron deficiency anemia because your body uses stored and recycled iron in forming new blood cells when you don't get enough in your diet. Once the iron supply begins to deplete, your body actually decreases the production of red blood cells and the potential for the condition becomes a reality.

Causes

There are several possible causes of low iron levels and, therefore, iron deficiency anemia.

Diet and Absorption

Iron deficiency can occur if you don't eat enough iron-containing foods or if you have trouble absorbing iron. Vegetarians and vegans may be more prone to iron deficiency because the form of iron found in plants (non-heme iron) is not absorbed as well as iron found in meat, poultry, and fish (heme iron). Calcium can interfere with the absorption of iron, and therefore eating foods high in calcium at the same time as food rich in iron can prevent you from absorbing enough iron from your meal.

Some illnesses prevent absorption of iron, including irritable bowel syndrome, lupus, and celiac disease. Gastric bypass, which often involves removal of sections of the stomach or intestines, may also interfere with adequate iron absorption.

Extra Iron Requirements

Pregnant women have a higher blood volume, and a developing fetus also needs oxygen-rich red blood cells to provide energy. As such, they require more iron. Some mothers-to-be, particularly those not taking prenatal vitamins—may fall short of that goal.

Growing babies, children, and teens, also need additional iron to provide the actively growing body with enough energy for the additional metabolism that cells need to grow and develop.

Blood Loss

Normal or heavy menstrual bleeding can lead to iron deficiency anemia, and women generally need more iron than men for this reason.

Ulcers, hemorrhoids, polyps, colon cancer, or other medical conditions that cause chronic bleeding can also lead to blood loss that, if rapid, can cause low blood volume, as well as iron deficiency anemia. Symptoms, in these cases, are more substantial.

Bleeding due to surgery, childbirth, or an injury can also cause excessive blood loss.

You may be a little low in red blood cells, and therefore, iron, for a few days after donating blood. But healthy people who do so generally experience a correction of red blood cell volume without noticeable consequences.

Medical Conditions and Medication

Erythropoietin, a hormone produced by the kidneys, plays an important role in stimulating red blood cell production. If you have kidney disease, you may need erythropoietin replacement to stimulate red blood cell production, even if you have enough stored iron. Dialysis does not correct this hormone problem, and an erythropoietin deficit cannot be treated with dialysis.

Certain types of cancer, especially those that involve white blood cells, such as leukemia or lymphoma, which increase the risk of infections, are also associated with low red blood cell levels. While this is not truly iron deficiency, it interferes with the ability of iron to do its job.

Furthermore, most treatments for cancer suppress the production of red blood cells. As with leukemia, this does not decrease iron levels, but it prevents the iron in the body from doing what it is meant to do.

Associated Conditions

Some situations are associated with iron deficiency, although they don't cause it.

  • Lead poisoning is often associated with iron deficiency anemia, although it does not cause it. The anemia caused by lead poisoning exacerbates symptoms of other types of anemia, such as iron deficiency anemia.
  • A high-fiber diet, similarly, was considered a cause of iron deficiency anemia in the past, but this has been disproven. Many people who consume a lot of fiber due so to avoid constipation. And while constipation itself does not cause iron deficiency, those who routinely experience trouble having bowel movements may purposefully avoid iron-rich foods. This diet shift can lead to low iron levels.
  • Calories, whether from carbohydrates, protein, or fats, do not affect the iron absorption or content. Nevertheless, those who are underweight, whether due to health problems, anorexia, or dieting, are often iron deficient because they don't consume enough iron in the diet.

Symptoms

Iron deficiency anemia is the first manifestation of low iron. If you have iron deficiency anemia, it can produce several symptoms that may progress quickly or may manifest over the course of weeks or months.

  • Fatigue
  • Weakness
  • Problems with memory and thinking
  • Feeling cold
  • Headaches or dizziness
  • Dry, brittle hair, skin, and nails
  • Pica (strange cravings for metal, dirt, paper, or starchy food)
  • Glossitis (red, inflamed tongue)
  • Frequent infections
  • Heart palpitations
  • Shortness of breath
  • Restless legs syndrome

If you are severely iron deficient, or if you have experienced rapid blood loss, your symptoms can come on faster than if you suffer from moderate iron deficiency.

Complications

In extreme situations, iron deficiency anemia can cause tachycardia (a rapid heart rate) and low blood pressure. It may contribute to learning and concentration problems in children.

Pregnant women who have iron deficiency have low energy and have an increased risk of low birth weight babies and premature birth.

Diagnosis

It is rare to detect or test for iron deficiency itself based on symptoms alone since anemia is usually the first sign. A blood test is considered the most reliable and sensitive diagnostic tool for iron deficiency anemia.

Typically, a routine complete blood count (CBC) can identify iron deficiency anemia, often before symptoms become obvious. The CBC results that reflect iron levels include:

  • Hemoglobin level: Hemoglobin is the iron-containing protein in red blood cells that binds to oxygen. Normal hemoglobin levels should be 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, and 11 to 12 g/dl for pregnant women. While there are other causes of low hemoglobin, such as severe malnutrition, lower-than-normal levels are suggestive or iron deficiency anemia, which is the most common cause.
  • Hematocrit level: A hematocrit level is the red blood cell percentage of your whole blood. Normal hematocrit levels are 38 percent to 46 percent for women, and 42 percent to 54 percent for men. A low hematocrit is suggestive of low red blood cells or high white blood cells in the body.
  • Mean corpuscular volume (MCV): This test measures the average volume of each red blood cell, which is normally between 80 and 96 femtoliters per cell. A low MCV, particularly with a wide variation in average red blood cell size, is highly suggestive of iron deficiency anemia.

Sometimes, follow-up testing with a microscopic examination of the red blood cells (to assess quality and size) or an iron level may be needed after a CBC identifies iron deficiency anemia. A normal iron level ranges between 10 to 30 ug/L.

Physical Examination

While a physical examination is usually the most valuable part of diagnostic testing for many conditions, the manifestations of iron deficiency, including pale skin, a rapid heartbeat, and orthostatic hypotension (substantially lower blood pressure when standing), are very late effects that occur weeks or months after the blood tests become abnormal.

Follow-Up Testing

Once iron deficiency anemia is identified, it is very important to find the cause. Generally, if iron deficiency anemia is detected in a blood test, the next steps often include a search for a blood disease or for occult blood loss, which is hidden or unnoticed blood loss.

  • Occult blood loss: The most common cause of occult blood loss is bleeding from the colon, and a stool sample is usually sent to a lab to see if there is blood. Even when a stool sample is negative (no blood), if there is no obvious cause or iron deficiency, further testing with colonoscopy or endoscopy may be needed, depending on the risk. Colonic polyps, bleeding ulcers, and even gastrointestinal cancer are causes of iron deficiency.
  • Blood disease: A CBC often reflects abnormalities of white blood cells associated with leukemia or lymphoma.

Treatment

Treatment of iron deficiency is based on two important approaches: correcting the underlying problems and replacing iron levels.

Replacing Iron Levels

Iron levels can be corrected either by increasing iron in the diet, taking iron supplements in pill form, or, for situations that don't improve with these options, a parenteral (in the muscles) injection of iron may be necessary. If your iron deficiency is due to an intestinal problem, pills and food usually cannot correct the problem, because you still can't absorb iron, even if you take enough by mouth.

Medical or Surgical Intervention

Depending on the cause, you may need intervention to stop the process of iron deficiency. A bleeding polyp in the colon may need removal (and biopsy to make sure it isn't cancer). If you experience stomach bleeding due to blood thinners, you may need a lower dose or a different blood thinner altogether. And if you have had a major episode of blood loss due to an event such as surgery or trauma, you may have a blood transfusion rather than an iron replacement.

Prevention

You can usually prevent iron deficiency by consuming the right amount of iron in your diet. Healthy adult men need about 8 mg of iron per day, and healthy premenopausal adult women need 18 mg per day, while healthy pregnant women need 27 mg per day. After menopause, healthy women only need about 8 mg per day because they do not experience blood loss due to menstruation.

If you have a situation that interferes with your iron levels, you may need higher amounts, either through your diet or with an oral supplement. If oral supplements don't correct your iron levels, parenteral injections may be needed.

Meat, poultry, legumes, oysters, tuna, pork, nuts, dark green vegetables, tomato juice, and potatoes are all good sources of dietary iron. 

You can increase the amount of non-heme iron you absorb by combining vegan sources of iron with a food rich in vitamin C. For example, you can drink a glass of orange juice with a plate of spinach, or add green peppers to beans.

Dietary Supplements

Prenatal vitamin supplements usually contain iron, and women with heavy periods may need supplemental iron as well. Most men and postmenopausal women get enough iron from food and should not take iron supplements unless prescribed by a healthcare provider. If you need to take an iron supplement, don't take more than 45 mg per day unless your doctor instructs you to do so.

Iron supplements can cause uncomfortable constipation, even at the recommended doses. They can also cause more serious side effects, such as iron toxicity. Iron supplements are especially dangerous for people who have hemochromatosis, a condition characterized by iron overload.

Adult iron supplements can be toxic for young children, too, so iron supplements should be kept in tightly capped, childproof bottles.

Was this page helpful?
Article Sources