| Even those with mild anemia can experience some weakness and fatigue. Moderate to severe anemia can also cause shortness of breath, rapid heartbeat, lightheadedness, headache, ringing in the ears (tinnitus), irritability, pale skin, restless leg syndrome, and mental confusion. Anemia may occur without symptoms, however, and be detected only during a medical examination that includes a blood test. In spite of the common association of anemia with thinness and pallor, a normal to heavy weight and healthy-looking skin color do not rule out anemia in people with risk factors and other symptoms. The symptoms of megaloblastic anemia from vitamin B12 or folic acid deficiencies include standard anemic symptoms and inflammation of the mouth (stomatitis) and tongue (glossitis), which involve the shrinking of its surface and edges. Of concern for patients with pernicious anemia is that folic acid supplements can mask the presence of this disease in its early stages but not cure it. (Only vitamin B12 is a cure.) Early neurologic symptoms of pernicious anemia include numbness and tingling, depression, memory loss, and irritability. Advanced nerve damage can cause loss of balance and staggering, confusion, dementia, spasticity, loss of bladder control, and impotence. Folic acid deficiency does not cause neurologic damage, although people with this deficiency can be irritable, forgetful, and experience personality changes. How Is Anemia Diagnosed? General Diagnostic Tests for Anemia 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 of a number of factors. A detailed medical, personal, and dietary history is a necessary first step. A physician should ask about any family history of anemia as well as gallbladder disease, jaundice, and enlarged spleen. Women should report any heavy menstrual bleeding. All patients should describe any occurrence of blood in the stool or other signs of internal bleeding, and even if no bleeding has been seen, a rectal exam and stool test for occult (hidden) blood are essential. The physician should examine the patient carefully, especially checking for swollen lymph nodes, an enlarged spleen, and pale skin and nail color. A dietary history is important, particularly in people who are elderly and poor. Blood Counts and Blood Smears. The basic laboratory tests for diagnosing anemia establish the number of red blood cells and their appearance (known as their morphology). A complete blood count (CBC) test is always performed. The red blood cells, or erythrocytes, and their iron-bearing component, hemoglobin, are measured. The percentage of red blood cells in the blood is called the hematocrit. A low RBC count could indicate a number of problems, including bleeding or a failure by bone marrow to manufacture red blood cells. Physicians must take into consideration smoking and high altitude, both of which can increase hemoglobin and hematocrit counts. With these conditions, the red blood cell count may be normal, but the patient may actually be anemic because insufficient oxygen is being delivered to the lungs. A blood smear allows an expert to classify the blood by its color, size, and shape—its morphology. Generally red blood cells are categorized as either being pale-colored (hypochromic) and abnormally small (micr
ocytic), normal colored and normal sized (normochromic, normocytic), or abnormally large (macrocytic). The shape of the red blood cells, which can be distorted in many blood disorders, is also important in determining a diagnosis. Diagnosing Iron Deficiency Anemia When blood smears reveal pale-colored and abnormally small cells that are often uneven in shape, iron deficiency is usually suspected, although this same morphology can appear in anemia of chronic disease and thalassemia. Iron levels should then be measured; low levels, however, can occur both in true iron deficiency anemia and anemia of chronic disease. To confirm a diagnosis of iron-deficiency anemia, physicians usually measure ferritin, a protein that binds iron; ferritin levels are low in iron deficiency but not usually in ACD. (It should be noted that women who have an iron deficiency and anemia when they become pregnant may test for high ferritin levels during pregnancy that persist into the third trimester, which indicate a risk for early delivery and low infant birth weight.) Another test that can distinguish iron deficiency from ACD is measurement of a factor in the blood called unsaturated iron-binding capacity (UIBC), which increases in iron deficiency but not in anemia caused by chronic diseases. When iron deficiency anemia is diagnosed, the next step is to determine what causes the iron deficiency itself. If iron deficiency is found in men or postmenopausal women, a physician should always look for causes other than dietary ones. A diagnosis of internal bleeding can be made simply if the patient has noticed blood in the stools, which can be black and tarry as well as red-streaked. Often, however, the bleeding is not apparent, a condition known as occult (hidden) bleeding, and tests for blood in the stools are almost always required. Additional tests may then be needed to diagnose the precipitating condition, which may be gastrointestinal cancer, colon polyps, ulcers, gastritis, hiatal hernias, or long-term use of aspirin or similar pain killers called nonsteroidal anti-inflammatory drugs (NSAIDs). In some cases, particularly in the elderly, the cause of bleeding is unknown. For these patients, physicians sometimes use a technique called endoscopy, which involves the use of a fiber-optic tube to view the gastrointestinal tract. If no problems are detected, the patient is placed on iron supplements. If the patient fails to respond or requires transfusions, further evaluation is needed. Although endoscopy is not always performed in older patients with iron deficiency and no signs of GI bleeding, one study reported that this procedure revealed specific causes of anemia, including some cancers, in 44% of patients who had no other indications of bleeding. Diagnosing Causes of Anemia from Chronic Diseases The blood cells are normal looking in most cases of anemia caused by chronic disease. Usually the anemia is recognized during the management of the primary disease and, if the anemia is mild, additional diagnostic tests are rarely needed. Low levels of iron in the blood are often found in ACD, but ferritin levels are normal or high, ruling out true iron deficiency. It must be noted, however, that internal bleeding may also accompany ACD and confuse the diagnosis. For example, rheumatoid arthritis is associated with anemia, but NSAIDs taken for pain relief from arthritis can also cause gastrointestinal bleeding and, therefore, iron deficiency. Cancer patients may have anemia caused both by internal bleeding and the disease process itself. Diagnosing Megaloblastic Anemia and Vitamin B Deficiencies Physicians may arrive at a diagnosis of vitamin B12 or folic acid deficiencies from different routes. They may suspect vitamin deficiencies from patient symptoms or diagnose deficiences after detecting megaloblastic anemia from abnormal blood tests. If a vitamin B12 deficiency is uncovered, the next step is to test for pernicious anemia. Once identified, pernicious anemia is simple to treat, although it is easily missed. Symptoms and History Indicating Vitamin B12 or Folic Acid Deficiency. Malnutrition, alcohol abuse, pregnancy, a history of sprue, severe psoriasis, or the use of antiseizure drugs may indicate a folic acid deficiency. A history of stomach surgery, eating raw fish (which raises the possibility of tapeworm), inflammatory bowel disease, or hypothyroidism suggests vitamin B12 deficiency. Often, vitamin B deficiencies cannot be determined by a history or symptoms alone. If a vitamin B12 deficiency is present and caused by pernicious anemia, a physician may not suspect this disease in patients whose diets are rich in folic acid. Folic acid can prevent the anemic symptoms of pernicious anemia but not cure it; consequently in can mask the disease until serious neurologic symptoms occur. With folic acid now a required additive in many commercial foods, some experts are concerned that there will be an increased incidence of cases of undetected pernicious anemia. Tests for Megaloblastic Anemia. Blood tests indicate megaloblastic anemia by revealing very large oval red blood cells. They also may show abnormally shaped neutrophils, which are white blood cells. Bone marrow aspiration is usually not necessary but may be performed if the diagnosis is unclear. Determining Specific Vitamin Deficiencies and Pernicious Anemia. Once megaloblastic anemia has been diagnosed, the physician will need to determine what vitamin deficiency is causing it. Patients who have neurologic and psychiatric abnormalities with no detectable cause should still be tested for vitamin B12 deficiency, even if blood tests for megaloblastic anemia are normal. Blood tests are the primary indicators of both vitamin B12 and folic acid deficiencies. (Folic acid levels are best measured by its levels in samples of red blood cells.) Folic acid and vitamin B12 levels must always be measured at the same time because each vitamin may affect the other. For instance, vitamin B12 levels tend to exhibit a false drop if folic acid levels are low. Folate levels may be temporarily low in some people who are not truly deficient or falsely high in some people who are deficient but have just eaten foods containing the vitamin. Antibiotics can interfere with B12 levels. Measuring methylmalonic acid and homocysteine, substances in the blood that increase when levels of one or both vitamins decrease, improves accuracy. Other tests are used to detect antibodies to intrinsic factor and stomach cells damaged by pernicious anemia. Until recently, the only methods for diagnosing pernicious anemia were either a trial of vitamin B12 injections or a urine test known as the Schilling test, which is not completely reliable. Some clinicians no longer use it because of improvement in blood tests. Once a vitamin B12 deficiency has been established and the physician has not found any intestinal abnormalities or other factors to account for the deficiency, the doctor presumes a diagnosis of pernicious anemia. |
