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Blood travels through the arteries and veins, delivering oxygen and nutrients to body cells. Blood that is carrying oxygen is bright red, but it becomes dark purple after it gives up that oxygen to body tissues and enters the veins. The cells in the blood consist of the red blood cells (RBCs), the white blood cells (WBCs), and the platelets. RBCs carry oxygen to body tissues. WBCs are active in the immune system, defending the body from bacteria, viruses, fungi, and other types of infections. Platelets function in blood clotting. In general, the blood itself changes very little with aging, but diseases that cause abnormalities in the blood are common in older people. Anemia Anemia is a low level of hemoglobin in the blood. Hemoglobin is a molecule in the RBCs that contains iron and carries oxygen for delivery to tissues. The lower limit of normal hemoglobin in older adults is about 12 grams per ten milliliters of blood. Anemia is not a consequence of normal aging in healthy people, although it is commonly found in older adults. Symptoms of anemia include the following:
Causes Anemia can result from several different causes involving either decreased or poor RBC production or increased RBC destruction. In many older adults, anemia is caused by more than one condition. Causes of Anemia in Older Adults
Decreased or poor RBC production Most anemia in older adults is caused by decreased production of RBCs. Often, an iron deficiency in the bone marrow limits the production of RBCs. Iron deficiency can be caused by poor nutrition, and usually the person has a history of weight loss and low levels of protein in the blood. However, poor nutrition is only rarely the cause of iron-deficiency anemia in older adults. In fact, most people take in so much iron during their lives that the amount of iron stored in the body keeps increasing with age. The most common cause of iron-deficiency anemia in older adults is what is called "anemia of chronic disease." It can result from chronic inflammation that can be caused by ongoing infection, tissue damage, various forms of arthritis, and benign or malignant tumors. In this type of anemia, the body is unable to "recycle" iron, so that the iron stored in older RBCs can't be reused when these RBCs die normally. Another common cause of iron-deficiency anemia is chronic blood loss, usually from the gastrointestinal tract. This can be caused by bleeding ulcers or polyps, chronic irritation of the lining of the gastrointestinal tract, or cancer. Often, this loss of blood in the bowels is not visible to the naked eye, and special testing is needed to find it. Chronic, low-level bleeding reduces the body's iron stores, removing the main building block for RBC production. Problems in the bone marrow can also decrease RBC production. Inflammation from chronic diseases can cause the bone marrow to be sluggish, and kidney problems can decrease the signals that tell the marrow to make more blood cells. At other times, the problem with RBC production may be a malfunction in the bone marrow itself. In this condition, known as aplastic anemia, usually WBCs and platelets are also decreased. Common causes include drugs, immune disease, problems arising directly within the bone marrow, and replacement of the bone marrow by malignant cells (eg, leukemia) or other tissue. In some cases, enough RBCs are produced, but they don't mature properly. Most immature RBCs are unable to leave the bone marrow and enter the circulation. This type of anemia is usually classified according to the size of the RBCs in the circulation. If the RBCs are normal are small in size, the anemia is usually due to heredity diseases or other rare disorders. If the RBCs are very large, the anemia (called pernicious anemia) is almost always caused by a deficiency of either vitamin B12 or folic acid (another vitamin). Vitamin B12 deficiency becomes much more common with advancing age, developing most often in women over the age of 60. Signs and symptoms include the following:
Vitamin B12 deficiency is generally caused by problems absorbing B12 from the gut, rather than from not getting enough in the diet. Poor absorption can be caused by changes in the stomach that affect the absorption of vitamin B12 from food, chronic pancreatitis ,or inflammation in the small bowel. Pernicious anemia can also be caused by folic acid deficiency, but this is rare. The most common causes of folic acid deficiency in older adults are poor nutrition and alcoholism. Alcohol and other drugs can interfere with the body's absorption of folic acid. Folic acid deficiency often develops when the body is stressed and needs more of this vitamin, such as when there is inflammation or cancer, or when RBCs are being destroyed. Increased RBC destruction Anemia caused by RBC destruction is called hemolytic anemia. The most common cause in older adults is destruction of RBCs by the body's immune system. This destruction is often linked with cancer of the lymph glands or blood cells, such as non-Hodgkin's lymphoma or chronic lymphocytic leukemia (see Cancer). Anemia caused by RBC destruction can also be due to an immune system disease (eg, collagen vascular disease) or by medications. Diagnosis The cause(s) of anemia in older adults can be difficult to diagnosis. Many conditions can cause anemia in older people, and several of them may happen at the same time. Despite a thorough evaluation, sometimes the cause of anemia remains uncertain. The evaluation of anemia generally begins with a history and complete physical examination. Your healthcare provider will take a blood sample for a complete blood count. RBC size can be measured, and the rate of RBC production can be estimated. Special blood tests can determine how much iron is stored in the body and whether this iron is binding to various proteins the way it should. Your healthcare provider may also want to measure levels of vitamin B12 and folic acid. Evaluation for underlying illness that could cause chronic bleeding into the gut (eg, ulcers or polyps) or anemia of chronic disease (eg, cancer or rheumatoid arthritis) may require additional blood tests, x-rays, endoscopy, or bone marrow biopsy. Treatment Treatment is aimed at the underlying cause of anemia. For example, pernicious anemia is treated with periodic injections or pills of vitamin B12 or folic acid. People with hemolytic anemia may be treated with corticosteroids, or they may need to have their spleen removed. In some severe anemias, injections of hormones can increase RBC production by the bone marrow. Usually, blood transfusions are not needed. Bleeding and Clotting Disorders As mentioned earlier, platelets are important for blood clotting. Substances in the blood called clotting factors are also necessary for a clot to form properly. When a blood vessel is injured, platelets enlarge and clump together to form a clot. Blood clotting involves the following processes, all going on at the same time:
Older adults are more prone to bleeding problems than younger people. Bleeding problems may show up as unexplained bruises, repeated nosebleeds, bleeding into the gut, or a large amount of blood loss during surgery or a dental extraction. Causes The causes of bleeding disorders in older adults are complex but can be divided into three categories: Decreased number of platelets When there are fewer platelets in the blood than usual, the blood does not always form a clot. Usually, there is bleeding from the mouth, the gastrointestinal tract, or the urinary system. The two most common causes for too few platelets are that the bone marrow doesn't produce enough platelets, or that too many platelets are destroyed in the blood. In older adults, the most common reason the bone marrow doesn't produce enough platelets is because it is affected by certain drugs such as the chemotherapy drugs used to treat cancer. The bone marrow can also be affected by diseases of the blood (eg, leukemia) and by cancers that invade the bone marrow (eg, lymphoma). Too many platelets can be destroyed by "scavenging cells" in the spleen and liver. These scavenging cells are programmed to destroy platelets that become coated with antibody, which happens in certain diseases (such as lymphoma and systemic lupus erythematosus) or as a side effect of many commonly prescribed drugs. In fact, so many drugs (including penicillin, heparin, and diuretics ["water pills"]) can cause too many platelets to be destroyed that all medications should be considered a possible cause of a low platelet count. Platelets that don't work properly Sometimes there are enough platelets, but they don't function normally. This is rare, but when it does happen, the bleeding problem is serious. The most common cause is a disease called von Willebrand's disease, which is a congenital condition that can sometimes show up in older life. In von Willebrand's disease, there aren't enough of the clotting factors that are needed for platelets to stick to the walls of blood vessels. Platelet also may not work properly in certain cancers (eg, lymphoma or myeloma), kidney failure, and heart-lung bypass surgery. A large number of medications can affect platelet function, most commonly aspirin. Abnormal clotting factors Problems with clotting factors can also result in bleeding. In older adults, the most common cause is deficiency of vitamin K, which the liver needs to make clotting factors. Vitamin K deficiency is most commonly caused by anticoagulants, which are used to thin the blood of people who are at increased risk of heart attack or stroke (see also Disorders of the Heart and Circulatory System and Diseases of the Nervous System). Some types of anticoagulants prevent blood clotting by interfering with vitamin K. In cases of severe malnutrition, vitamin K deficiency can also be caused by too little in the diet. In some instances, antibiotics used to fight infection can interfere with the bacteria in the gut that are a major source of vitamin K. Deficiency of the clotting factors can result from a variety of major illnesses. For example, liver disease can affect production of clotting factors. In certain intestinal problems, vitamin K is not well absorbed in the gut. Diagnosis and treatment Bleeding disorders are evaluated using a variety of blood tests that measure the number of platelets in the blood, the time it takes the blood to clot, vitamin K levels, etc. In some instances, bone marrow biopsies may be needed to evaluate platelet production in the bone marrow. Treatment of bleeding disorders depends on the underlying cause, and may include the following:
Decreased White Blood Cells White blood cells (WBCs) play an essential role in fighting infection. They are also important in inflammation. As WBC levels decrease, the chances of infection by bacteria or fungi increases. Like numbers of RBCs in anemia, decreased numbers of WBCs can be caused by decreased or poor WBC production, or by increased WBC destruction. Causes of Decreased White Blood Cells in Older Adults
In older adults, a low WBC count is most often a side effect of medical treatments, including radiation and chemotherapy for cancer, and various other drug treatments. In some cases, the decrease in WBCs depends on the dosage of the treatment. In other cases, the decrease in WBCs is thought to be due to allergic or immune reactions unrelated to dosage. Other common causes for a low WBC count include cancer, immune diseases (eg, lupus or rheumatoid arthritis), and infection. Severe infection can influence WBC levels in two ways, decreasing production in the bone marrow while destroying WBCs in the circulation at the same time. The evaluation of a WBC problem includes tests to measure the number and types of cells in the blood, and a bone marrow biopsy. Treatment is directed at the underlying cause. |
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Published: 8/30/2005