When red blood cells are degraded, the iron is recycled by the body and stored.When the amount of iron needed by the body exceeds the amount of iron that is readily available, the body can use iron stores (ferritin) for a period of time, and red blood cell formation continues normally. However, as these stores continue to be used, iron is eventually depleted to the point that red blood cell formation is abnormal. Ultimately, anemia ensues, which by definition is a hemoglobin lab value below normal limits. Diagnosis
Conventionally, a definitive diagnosis requires a demonstration of depleted body iron stores obtained by bone marrow aspiration, with the marrow stained for iron. However, with the availability of reliable blood tests that can be more readily collected for iron-deficiency anemia diagnosis, a bone marrow aspiration is usually not obtained. Furthermore, a study published April 2009 questions the value of stainable bone marrow iron following parenteral iron therapy. Once iron deficiency anemia is confirmed, gastrointestinal blood loss is presumed to be the cause until proven otherwise since it can be caused by an otherwise asymptomatic colon cancer. Initial evaluation must include esophagogastroduodenoscopy and colonoscopy to evaluate for cancer or bleeding of the gastrointestinal tract.A thorough medical history is important to the diagnosis of iron-deficiency anemia. The history can help to differentiate common causes of the condition such as a menstruation in woman or the presence of blood in the stool.
A travel history to areas in which hookworms and whipworms are endemic may also be helpful in guiding certain stool tests for parasites or their eggs. Although symptoms can play a role in identifying iron-deficiency anemia, they are often vague, which may limit their contribution to determining the diagnosis. Blood tests
Anemia is often discovered by routine blood tests. A sufficiently low hemoglobin by definition makes the diagnosis of anemia, and a low hematocrit value is also characteristic of anemia. Further studies will be undertaken to determine the anemias cause. If the anemia is due to iron deficiency, one of the first abnormal values to be noted on a complete blood count, as the bodys iron stores begin to be depleted, will be a high red blood cell distribution width, reflecting an increased variability in the size of red blood cells.A low mean corpuscular volume also appears during the course of body iron depletion. It indicates a high number of abnormally small red blood cells. A low mean corpuscular volume, a low mean corpuscular hemoglobin or mean corpuscular hemoglobin concentration, and the corresponding appearance of red blood cells on visual examination of a peripheral blood smear narrows the problem to a microcytic anemia (literally, a small red blood cell anemia).The blood smear of a person with iron-deficiency anemia shows many hypochromic (pale, relatively colorless) and small red blood cells, and may also show poikilocytosis (variation in shape) and anisocytosis (variation in size).