What’s the Link Between Crohn’s Disease and Iron-Deficiency Anemia?

Here’s what you should know about the relationship between Crohn’s disease and iron-deficiency anemia, and about identifying and getting treatment for this potential complication of Crohn’s.

This type of anemia occurs when you’re not getting enough iron or are losing too much iron. Your body needs adequate iron to produce hemoglobin, a substance in red blood cells that enables them to carry oxygen. This is why iron-deficiency anemia may cause fatigue and leave you feeling short of breath.

Although low iron levels in your body can have a number of potential causes, in people with Crohn’s disease, the most common cause is blood loss in the digestive tract. When this happens, people “are usually unaware that they are losing blood,” says James F. Marion, MD, a gastroenterologist and IBD expert at Mount Sinai Hospital in New York City. That’s because the blood loss can happen gradually over a long period of time without overt symptoms.

In people with Crohn’s disease, Dr. Marion says, this blood loss usually occurs because of disease activity. The digestive tract contains lots of blood vessels, he notes, which can rupture when Crohn’s-related ulcers and fissures penetrate beneath the inner mucosal layer of the intestines.

Anyone with Crohn’s disease can develop iron deficiency in this way. But Marion notes that people who already have a higher risk of iron deficiency to begin with — namely, women of childbearing age, who may lose a significant amount of iron each month in their menstrual blood — are more likely to develop the condition and to develop it more quickly.

Other potential causes of low hemoglobin include vitamin B12 deficiency due to poor absorption in the intestines and anemia of chronic inflammation — a form of anemia, Marion notes, that’s often seen in many chronic and inflammatory disorders.

• Extreme fatigue
• Weakness
• Pale skin
• Chest pain, fast heartbeat, or shortness of breath
• Headache, dizziness, or lightheadedness
• Cold hands and feet
• Inflammation or soreness of the tongue
• Brittle nails
• Unusual cravings for nonnutritive substances, such as ice, dirt, or starch
• Poor appetite

“Blood loss and anemia bring on symptoms that can feel pretty global,” Marion notes. “These are very debilitating symptoms, and if you add these on top of existing [Crohn’s symptoms such as] abdominal pain and diarrhea, it’s a pretty terrible situation for someone to be in.”

If someone with Crohn’s disease is found to be anemicor iron deficient, Marion says, it can prompt efforts both to treat these complications and to look at inflammatory markers as part of a general reevaluation of Crohn’s treatments.

“It can sometimes be a reason to restage the individual’s disease,” he says, “meaning that you put them a bit more under a microscope.” This may include tests like magnetic resonance imaging (MRI) of the small intestine or a colonoscopy to look for polyps or colorectal cancer.

If you’re iron deficient because of Crohn’s disease activity, Marion says that it’s important to address both the underlying inflammation and the deficiency itself when devising a course of treatment.

“Think of your body as a bucket that holds iron,” he explains. If you have Crohn’s inflammation, it’s like poking a couple of holes in that bucket. If your treatment focuses only on iron supplementation, you’ll be pouring more iron into the bucket, but it will still leak out — with inflammation continuing to cause blood loss and progressive damage to your GI tract.

Oral Iron Supplements and IV Iron Infusions

To treat iron deficiency, your doctor may prescribe oral iron supplements or intravenous (IV) iron infusions depending on the severity of the iron deficiency. “If you want to get a quick and sure dose of iron into a patient,” says Marion, “there’s nothing better than administering it intravenously, because you know the entire dose is going to make it into the body.”

Both oral supplements and IV iron are associated with certain risks. Crohn’s-related absorption problems may limit the effectiveness of oral supplements in some people. In addition, oral iron can cause GI irritation, leading to symptoms like constipation and nausea. In rare cases, IV iron can cause an allergic reaction, says Marion. “You just have to tailor treatment to the individual patient,” he notes, while looking out for problems that may arise.

It may also be worthwhile to examine the iron content of your diet, Marion says. That’s especially important if you avoid eating red meat, whether because of Crohn’s-related considerations or because you’re vegetarian or vegan. Getting enough iron from red meat requires that you consume only about two to three portions a week, Marion notes.

• Pork and poultry
• Eggs
• Seafood
• Green leafy vegetables, such as spinach
• Iron-fortified cereals, breads, and pasta
• Dried fruits
• Beans and other legumes, such as peas

You can also improve your body's absorption of iron by drinking citrus juice or consuming other foods rich in vitamin C simultaneously while you eat foods that are high in iron.

But when you have Crohn’s disease and develop iron deficiency, “you really want to treat the root of the problem, recognizing that it’s an extraintestinal manifestation of Crohn’s,” Marion says. So if this happens to you, see your doctor to make sure that your Crohn’s is being controlled as well as possible.

• Iron-deficiency anemia, the most common type of anemia, is a condition in which your blood does not have enough healthy red blood cells to carry oxygen to the body's tissues, causing fatigue, weakness, and shortness of breath.
• Iron-deficiency anemia is one of the most common systemic complications of Crohn’s disease.
• Although low iron levels in your body can have a number of potential causes, in people with Crohn’s disease, the most common cause is blood loss in the digestive tract.
• To treat iron deficiency, your doctor may prescribe oral iron supplements or intravenous (IV) iron infusions depending on how severe the iron deficiency is. You can also try adding more iron-rich foods to your diet if your iron deficiency is mild.