OVERVIEW: What every practitioner needs to know
Are you sure your patient has iron deficiency anemia? What are the typical findings for this disease?
Iron deficiency anemia is the most common nutritional deficiency in childhood. This disease is characterized by a
OVERVIEW: What every practitioner needs to know
Are you sure your patient has iron deficiency anemia? What are the typical findings for this disease?
Iron deficiency anemia is the most common nutritional deficiency in childhood. This disease is characterized by a microcytic anemia, which can be caused by decreased intake and/or increased loss of iron. Iron deficiency causes a slow progressive form of anemia and thus is generally not associated with significant symptoms until hemoglobin levels are critically low.
Etiology of iron deficiency anemia
Primary causes of iron deficiency anemia can be broken down into decreased supply of iron and/or increased loss of iron.
Decreased Iron Supply
Although equal amounts of iron are present in cow’s milk and breast milk, the iron in breast milk is more readily absorbed. However, even in breast-fed infants the demand exceeds supply in rapid growth phases. Iron supplementation is recommended in children older than the age of 6 months who are exclusively breast-fed. Also, cow’s milk is to be avoided until age 1 year.
Premature infants do not have adequate iron stores to satisfy increased iron requirements in the first year of life due to rapid growth. This results from the fact that most prenatal tissue iron stores develop during the last trimester of pregnancy.
Meat versus vegetable sources also has an effect on availability. Heme from animal tissues is the most easily absorbed form of iron. As a result, vegetarians are at higher risk of iron deficiency.
Decreased gastric pH can also limit iron absorption, which can be a concern in patients receiving aggressive acid blocker for gastrointestinal (GI) disease such as peptic ulcer disease.
Primary bowel disease (e.g., inflammatory bowel disease, celiac sprue, intestinal resection) that damages the small intestine, causing poor nutrient absorption, will directly impair iron absorption.
It is unclear if lead toxicity directly impairs absorption or selectively competes with iron, but it is commonly associated with iron deficiency.
Increased Iron Losses
GI blood loss is the leading cause of iron deficiency. Occult bleeding can be present for a prolonged period before it is clinically detected. Common pediatric causes of GI bleeding include Meckel diverticulum, peptic ulcer disease, superficial arteriovenous malformations, GI irritiation from cow’s milk, GI malignancy, and parasitic infection.
Chronic menorrhagia can lead to iron deficiency.
Urinary blood loss from an underlying renal disorder (Berger and Goodpasture syndromes) can cause iron deficiency associated with gross (versus microscopic) hematuria.
Pulmonary blood loss leading to iron deficiency is extremely rare and may be associated with pulmonary hemosiderosis.
Symptoms of iron deficiency anemia
Since there is a gradual progression of anemia, a patient with iron deficiency anemia can be relatively asymptomatic. General symptoms include pallor, weakness, fatigue, palpitations, and lightheadedness. Rarely patients will have angular stomatitis and glossitis. Patients can also exhibit pica behavior – most classic is eating excessive ice. Studies have shown that iron deficiency (with or without anemia) leads to impaired growth and intellectual development in children. Some of these cognitive effects are not reversible with iron repletion.
What other disease/condition shares some of these symptoms?
Iron deficiency versus thalassemia trait
Iron deficiency anemia is often confused with thalassemia trait. Both are associated with anemia and microcytosis. However, red cell distribution width (RDW) and cell hemoglobin distribution width are normal in thalassemia trait. Iron studies (ferritin, serum iron, total iron binding capacity) should be normal in a child with thalassemia. The mean corpuscular volume (MCV) tends to be disproportionately low compared with the hemoglobin level in thalassemia trait (very low MCV with mild anemia). Patients may have both conditions concurrrently. It is important to note that iron deficiency must be treated adequately before determining if a patient has beta-thalassemia trait, as iron deficiency suppresses hemoglobin A2 synthesis. If after adequate treatment, the patient maintains a microcytic anemia, he/she also likely has coexistent thalassemia trait (see Table I).
|Laboratory Tests||Iron Deficiency||Thalassemia Trait|
|Complete blood count|
MCV = mean corpuscular volume; RDW = red cell distribution width; total iron binding capacity
What caused this disease to develop at this time?
Children at greatest risk for iron deficiency anemia are premature infants, toddlers (aged 1-3 years), and teenage girls who are menstruating.
Premature infants lack the tissue iron stores present in full-term infants, since most iron stored occurs in the third trimester of pregnancy.
Toddlers are at special risk for iron deficiency because of poor iron intake, particularly from excessive intake of cow’s milk. Children have increased iron requirements because of rapid growth. Iron deficiency can occur in children less than 1 year of age who are breast-fed because of poor bioavailability.
Cow’s milk is a poor source of iron. After children transition to cow’s milk, they are at risk for iron deficiency anemia from decreased intake of iron-rich foods. This risk has been mostly eliminated in children younger than 1 year of age with the use of iron-fortified formulas, although infants exclusively breast-fed after the age of 6 months are at risk because of depletion of iron stores from birth, rapid growth, and relatively low iron suppl