Iron deficiency; Pernicious anemia
The first step in any diagnosis is a physical examination to determine if the patient has symptoms of anemia and any complications. Because anemia may be the first symptom of a serious illness, determining its cause is very important. This may be difficult, particularly in the elderly, malnourished, or people with chronic diseases, whose anemia may be caused by one or more factors. A detailed medical, personal, and dietary history should report:
The doctor should examine the patient carefully, especially checking for swollen lymph nodes, an enlarged spleen, and pale skin and nail color.
A complete blood count (CBC) blood test is performed to determine the presence of anemia. Other iron status blood tests are also used.
A complete blood count (CBC) is a panel of tests that measures red blood cells, white blood cells, and platelets. For diagnosis of anemia, the CBC provides critical information on the size, volume, and shape of red blood cells (erythrocytes). CBC results include measurements of hemoglobin, hematocrit, and mean corpuscular volume.
Hemoglobin. Hemoglobin is the iron-bearing and oxygen-carrying component of red blood cells. The normal value for hemoglobin varies by age and gender. Anemia is generally considered when hemoglobin concentrations fall below 11 g/dL for pregnant women, 12 g/dL for non-pregnant women, and 13 g/dL for men.
The severity of anemia is categorized by the following hemoglobin concentration ranges:
Hematocrit. Hematocrit is the percentage of blood composed of red blood cells. People with a high volume of plasma (the liquid portion of blood) may be anemic even if their blood count is normal because the blood cells have become diluted. Like hemoglobin, a normal hematocrit percentage depends on age and gender. Anemic ranges for hematocrit generally fall below:
Other hemoglobin measurements such as mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) may also be calculated.
Mean Corpuscular Volume. Mean corpuscular volume (MCV) is a measurement of the average size of red blood cells. The MCV increases when red blood cells are larger than normal (macrocytic) and decreases when red blood cells are smaller than normal (microcytic). Macrocytic cells can be a sign of anemia caused by vitamin B12 deficiency, while microcytic cells are a sign of iron-deficiency anemia or thalassemias.
Serum Ferritin. Ferritin is a protein that binds to iron and helps to store iron in the body. Low levels typically mean reduced iron stores. Normal values are generally 12 - 300 ng/mL for men and 12 - 150 ng/mL for women. Lower than normal levels of ferritin are a sign of iron-deficiency anemia, while higher than normal levels may indicate hemolytic anemia, megaloblastic anemia, or anemia of chronic disease.
Serum Iron. Serum iron measures the amount of iron in the blood. A normal serum iron is 60 - 170 mcg/dL. Lower levels may indicate iron-deficiency anemia or anemia of chronic disease, while higher levels may indicate hemolytic anemia or vitamin B12 deficiency.
Total Iron Binding Capacity. Total iron binding capacity (TIBC) measures the level of transferrin in the blood. Transferrin is a protein that carries iron in the blood. TIBC calculates how much or how little the transferrin in the body is carrying iron. A higher than normal TIBC is a sign of iron-deficiency anemia. A lower than normal level may indicate anemia of chronic disease, sickle cell, pernicious anemia, or hemolytic anemia.
Reticulocyte Count. Reticulocytes are immature red blood cells, and their count reflects the rate of red blood cell production. The upper normal limit is about 100,000/mL. A low count, when bleeding isn't the cause, suggests problems in production in the bone marrow. An abnormally high count indicates that the red blood cells are being destroyed in high numbers and indicates hemolytic anemia. Recent research suggests that the reticulocyte hemoglobin content (CHr) test may be more accurate than a standard hemoglobin test for detecting iron deficiency in infants.
Vitamin Deficiencies. Tests for vitamin B12 and folate levels.
If internal bleeding is suspected as the cause of anemia, the gastrointestinal tract is usually the first suspect as the source. A diagnosis in these cases can often be made if the patient has noticed blood in the stools, which can be black and tarry or red-streaked. Often, however, bleeding may be present but not visible. If so, stool tests for this hidden (occult) blood are required. Additional tests may then be needed to diagnose the precipitating condition. Endoscopy, in which a fiber optic tube is used to view into the gastrointestinal tract, is helpful in many patients, particularly when the source of bleeding is unclear. A colonoscopy may also be recommended to rule out colorectal cancer.
If the patient's diet suggests low iron intake and other causes cannot be established using inexpensive or noninvasive techniques, then the patient may simply be given a monthly trial of iron supplements. If the patient fails to respond, further evaluation is needed.
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