Common Causes of Iron Deficiency Anemia—and How to Treat It
Nearly one-third of American adults may have an iron deficiency. We need iron to make hemoglobin, the substance in red blood cells that carries oxygen throughout your body. Common symptoms of iron deficiency include trouble concentrating and fatigue. But people experiencing these symptoms may assume they’re from another cause and not take steps to address the underlying iron deficiency. If left unchecked, iron deficiency can lead to iron deficiency anemia. Symptoms of iron deficiency anemia tend to develop gradually and are similar to symptoms caused by other types of anemia. Such symptoms include fatigue, weakness, shortness of breath, and paleness. With very low iron, some individuals experience symptoms of pica (wanting to eat a substance that’s not food, such as ice, dirt, paint, or chalk).
Addressing iron deficiency anemia starts with identifying and addressing the cause of the iron deficiency, then typically replenishing the body’s iron stores. Here’s a closer look at some of the most common causes of iron deficiency anemia and what people can expect when the condition is treated.
Cause #1 – General blood loss
In adults, iron deficiency is most commonly caused by loss of blood. This blood loss can come from several sources. A wound or trauma can cause significant blood loss over a short period of time. In women who have menstrual periods, menstrual bleeding is the most common cause of iron deficiency. Menstrual bleeding can sometimes be missed as a cause in young people. In men and postmenopausal women, iron deficiency usually indicates bleeding, most often in the digestive tract—for example, from a bleeding ulcer or a polyp in the colon. Chronic bleeding due to colon cancer is a serious cause in middle-aged and older adults.
Cause #2 – Decreased absorption
Decreased iron absorption in the digestive tract, known as malabsorption, can result from various disorders. Celiac disease is a common disorder to cause malabsorption. Other potential causes include bariatric surgeries and bowel removal, as well as rare genetic disorders.
Cause #3 – Inadequate diet / increased requirements
In the United States, anemia rarely results from consuming too little iron because supplemental iron is added to many foods. But for some populations with increased iron requirements, a diet with limited iron can lead to iron deficiency and even iron deficiency anemia. Pregnant women, who often begin their pregnancy with mildly reduced stores of iron, have increased iron requirements. As the pregnancy progresses, increased blood volume and the needs of the fetus can lead to iron deficiency--sometimes with anemia, sometimes without. Infants and young children can also be at risk of iron deficiency due to their diets, particularly if they’re especially picky eaters or consume a high amount of dairy.
Cause #4 – Dialysis
People on dialysis because of kidney failure, especially those taking medications that stimulate the body to make red blood cells (erythropoiesis-stimulating agents),can be at risk for iron deficiency. Typically, these individuals are routinely monitored for iron deficiency.
How Iron Deficiency Anemia is Diagnosed and Treated
It’s best to think of iron deficiency on a spectrum. Anemia may be the more serious outcome, but iron deficiency should be addressed even if a person is not yet anemic. Anemia is diagnosed with routine blood work known as a blood count. Diagnosing iron deficiency is a little more challenging. The most accurate test for iron deficiency is a measurement of the blood level of ferritin (a protein that stores iron). A low level of ferritin indicates iron deficiency. However, sometimes ferritin levels are misleading because they can be falsely elevated (and thus appear normal) due to liver damage, inflammation, infection, or cancer. People should make sure doctors know of any other medical conditions they have because some could influence test results.
Once an iron deficiency is identified, treatment consists of addressing the root cause of the deficiency, including stopping blood loss, and replacing the lost iron in the body. For most people, an iron-rich diet (including foods such as meats, shellfish, dried fruits, cereals, leafy greens, and beans) is not enough to replenish iron stores, and oral or intravenous supplementation is needed.
What to Know About Taking Oral Iron Supplements
Correcting iron deficiency anemia with oral iron supplements usually takes approximately 6 weeks, but may take longer to fully replete iron stores, even after the bleeding has stopped. Iron supplements are usually taken by mouth. Iron supplements make the stool look dark or black and often cause constipation.
Iron supplements have a reputation for causing digestive issues including bloating, cramping, and constipation. The good news is that most doctors will recommend taking the supplement every other day, which may help with absorption and reduce unpleasant side effects. People who are set to begin taking iron supplements should talk to their doctor about allergies and side effects before they start. There are several iron formulations the doctor may be able to provide, and sometimes other treatments such as stool softeners or vitamin C can help limit unpleasant digestive symptoms.
Ultimately, it’s important for patients to know that iron deficiency is relatively common and is important to get under control, whether it leads to anemia or not. For more on iron deficiency anemia, visit the Manuals page or the Quick Facts on the topic.