Iron Deficiency Anemia
Iron deficiency anemia is the most common type of anemia and it has many causes. Symptoms are related to the overall decrease in the number of red blood cells (RBCs) and/or the level of hemoglobin. If the iron deficiency anemia is mild to moderate, there may be no signs or symptoms. In addition to the most common signs and symptoms, there are some that are more unique to iron deficiency and may appear as iron stores in the body are chronically depleted. These may include:
- Brittle or spoon-shaped nails
- Swollen or sore tongue
- Cracks or ulcers at the corners of the mouth
- Difficulty in swallowing
- Craving to eat unusual non-food substances such as ice or dirt (also known as "pica")
Iron is an essential trace element and is necessary for the production of healthy RBCs. It is one component of heme, a part of hemoglobin, which is the protein in RBCs that binds to oxygen and allows RBCs to transport oxygen throughout the body. If not enough iron is taken in compared to what the body needs, then iron stored in the body begins to be used up. As iron stores are depleted, the body makes fewer RBCs with decreased amounts of hemoglobin in them, resulting in anemia.
Some of the causes of iron deficiency include:
- Chronic bleeding—if bleeding is excessive over a period of the time (chronic), the body's stored iron is gradually depleted and, as a result, the body cannot produce enough hemoglobin and red blood cells to replace what is lost. In women, iron deficiency may be due to heavy menstrual periods or bleeding fibroids. In older women and in men, the bleeding is usually from disease of the intestines such as ulcers and cancer.
- Dietary deficiency—iron deficiency may be due to a diet poor in iron. Meat, poulty, fish, and iron-fortified foods or dark leafy greens and certain beans are good sources of iron. Children and pregnant or nursing women especially need more iron due to increased requirements. In pregnant women, lack of iron can lead to low birth weight babies and premature delivery. Women who are pregnant, or planning to become pregnant, routinely take iron supplements to prevent these complications. Newborns who are nursing from deficient mothers tend to have iron deficiency anemia as well.
- Absorption problem—certain conditions affect the absorption of iron from food in the gastrointestinal (GI) tract and over time can result in anemia. These include celiac disease, Crohn disease, intestinal surgery such as gastric bypass, and reduced stomach acid from taking prescription medications.
Initial blood tests typically include a complete blood count (CBC). Results may show:
- Hemoglobin (Hb)—may be normal early in the disease but will decrease as anemia worsens
- Red blood cell indices—early on, the RBCs may be a normal size and color (normocytic, normochromic) but as the anemia progresses, the RBCs become smaller (microcytic) and paler (hypochromic) than normal.
- Average size of RBCs (mean corpuscular volume, MCV)—may be decreased
- Average amount of hemoglobin in RBCs (mean corpuscular hemoglobin, MCH)—may be decreased
- Increased variation in the size of RBCs (red cell distribution width, RDW)
A blood smear may reveal RBCs that are smaller and paler than normal as well as RBCs that vary in size (anisocytosis) and shape (poikilocytosis).
If a health care provider suspects that someone's anemia is due to iron deficiency, several follow-up tests may be run to confirm the iron deficiency. These may include:
- Serum iron—the level of iron in someone's blood
- Ferritin—a protein used to store iron; the small quantity of ferritin that is released into the blood is a reflection of the amount of stored iron in the body and is usually low with iron deficiency anemia. It is considered to be the most specific test for identifying iron deficiency anemia, unless infection or inflammation are present.
- Transferrin and total iron-binding capacity (TIBC)—transferrin is a protein that binds to and carries iron through the blood; TIBC is a reflection of how much transferrin is available to bind to iron. In iron deficiency anemia, the transferrin level and TIBC are high.
- Reticulocyte count—reticulocytes are young, immature red blood cells; the number of reticulocytes in iron deficiency anemia is low because there is insufficient iron to produce new RBCs.
- Soluble transferrin receptor (sTfR)—this test is primarily ordered to help distinguish between anemia that is caused by iron deficiency and anemia that is caused by inflammation or a chronic illness. It may be ordered as an alternative to ferritin when a person has a chronic illness and/or inflammation is present or suspected. It will be high in iron deficiency.
If the iron deficiency is thought to be due to chronic blood loss, such as gastrointestinal (GI) tract bleeding, then other tests and procedures may be performed. Laboratory tests that may be able to detect GI bleeding are the fecal occult blood test (FOBT) or fecal immunochemical test (FIT).
A test for Helicobacter pylori may detect a bacterium that can cause ulcers in the GI tract that may be a cause of chronic bleeding. If any of these tests are positive or if it is strongly suspected that a GI bleed exists, then procedures such as endoscopy or colonoscopy may be done to find the location of the bleeding so that it can be treated.
Treatment of iron deficiency typically involves iron supplements and/or a change in diet. Vitamin C also helps with iron absorption. However, if iron-deficiency is suspected to result from abnormal blood loss, further testing is often required to determine the reason for the bleeding. People with severe iron deficiency may require a transfusion of blood cells or iron therapy through intravenous (IV) or injections. When the underlying cause is found and treated, then the anemia is usually resolved.