Red Blood Cells

Red blood cells (RBCs), or erythrocytes, are nonnucleated biconcave disks that carry molecules of hemoglobin. The hemoglobin allows the transport and exchange of oxygen and carbon dioxide. The average life span of an erythrocyte is about 120 days. Although aging does not affect the life span of an erythrocyte, replenishment after bleeding may be delayed because of a decrease in blood-producing marrow of the long bones (McCance & Huether, 2008).

RBCs are necessary for maintaining oxygen and carbon dioxide transport. A reduction in the number of circulating RBCs, a decrease in the quality or quantity of hemoglobin, and/or a decrease in the volume of packed cells (hematocrit) is classified as anemia. Anemia may be attributed to (1) impaired erythrocyte production (bone marrow disease), (2) blood loss, (3) increased erythrocyte destruction, (4) dietary problems, (5) genetic disorders, or (6) a combination of the causes (McCance & Huether, 2008). Anemia is a clinical sign, not a disease process itself. Signs of anemia may be unnoticed if the anemia is mild, or the client may experience overt symptoms such as fatigue, shortness of breath, and paresthesia (McCance & Huether, 2008). In addition, clinicians can miss signs of anemia, even in markedly anemic older clients (Ham, Sloane, & Warshaw, 2001). The combination of vague symptomatology and vague clinical presentation may lead the health care provider to attribute an older adult’s complaints to “old age” and fail to investigate adequately.

Other conditions involving erythrocytes are related to increased cell numbers and abnormality in the cells themselves. Overproduction of RBCs is known as polycythemia. This may occur secondarily as a result of hypoxia due to chronic pulmonary disease or heart failure. In sickle cell anemia the RBCs become abnormal in shape and surface composition as a result of a genetic defect in the hemoglobin.

Hemoglobin

Hemoglobin is an important iron-containing protein that is carried on RBCs and makes up about one third of the weight of the RBC. Hemoglobin is necessary for the transport of oxygen. A reduction in hemoglobin can result in a decrease in oxygen content and an increase in fatigue, possibly indicating anemia. Abnormal hemoglobin from a genetic mutation can cause abnormalities of RBCs, as in sickle cell anemia.

Hematocrit

The hematocrit is the percentage of total blood volume that represents erythrocytes. This is determined in the laboratory by spinning (centrifuging) a sample of blood, causing the heavier red cells to sink to the bottom of the tube while the less dense plasma rises to the top. The percentage of cells to liquid is calculated, giving the hematocrit reading. An increase in the hematocrit can signal volume depletion (Beers & Berkow, 2000). A decrease in hematocrit may be a result of disease or dietary deficiencies (Pagana & Pagana, 2003).

Reported effects of aging on hemoglobin and hematocrit vary in the literature. Hemoglobin has been reported as remaining unchanged (Berghe, Wilson, & Ershler, 2004) or changing slightly, possibly from extrinsic factors rather than as a result of normal aging (Chatta & Lipschitz, 1999). Hematocrit and hemoglobin values decline slightly after the age of 90 (Sarkozi, 2002).

White Blood Cells

White blood cells (WBCs), or leukocytes, are another type of cell present in the blood. Their major function is defense against foreign substances. WBCs function mainly in the interstitial fluid. Leukocytes consist of neutrophils, lymphocytes, monocytes, eosinophils, and basophils. A decrease in leukocytes in older adults may be related to drugs or severe infection (Pagana & Pagana, 2003). Drugs that can cause a decrease in leukocytes include antibiotics, anticonvulsants, antihistamines, antimetabolites, cytotoxic agents, analgesics, phenothiazines, and diuretics (Pagana & Pagana, 2004). An increase in leukocytes is generally seen with infections. However, a white cell count may be only moderately elevated in older adults when an infection, such as pneumonia, is present. Other typical symptoms of infection such as fever, pain, and enlarged lymph glands (lymphadenopathy) may be minimal or absent in older adults with infections (Mouton et al, 2001). Consequently, the nurse must be alert to other signs and symptoms of impending infection, such as the sudden onset of confusion. Pharmacologic agents have also been associated with an increase in leukocytes. These drugs include allopurinol, aspirin, heparin, steroids, and triamterene (Pagana & Pagana, 2003).

Neutrophils, eosinophils, and basophils are produced in the bone marrow and possess similar structures of lobulated nuclei and many membrane-bound granules. Their primary function is phagocytosis (i.e., ingestion and destruction of particulate material). In addition, the basophil’s cytoplasmic granules contain powerful chemicals such as heparin, histamine, bradykinin, leukotrienes, and serotonin, which contribute to stimulation of the inflammatory response in tissues (McCance & Huether, 2008). The monocyte, the largest of the leukocytes, is produced in bone marrow and differs in appearance from neutrophils, eosinophils, and basophils. The monocyte has a single nucleus and is capable of destroying large bacterial organisms and virally infected cells by phagocytosis (Thibodeau & Patton, 2003).

Lymphocytes, the smallest of the leukocytes, are classified into two types: B and T. The lymphocytes have a large nucleus and relatively little cytoplasm. Originating in the bone marrow and thymus, lymphocytes are housed in the lymph nodes, spleen, and tonsils. Lymphocytes do not act as phagocytes but rather produce antibodies and other specific defenses against antigens (Thibodeau & Patton, 2003).

Aging does not appear to affect the function of neutrophils, although there is a reduced effect on the bone marrow to release and store these cells. Lymphocytes of older adults have shown impaired function in vitro and are suspected to be the cause of a reduction in antibody response in later life (Rothstein, 1999). There is suspicion that a decline in monocyte function exists given the increased susceptibility to infections and increased incidence of malignancies in older adults. The remaining leukocytes, eosinophils, and basophils, have not been shown to be affected by aging.

The presence and function of leukocytes are necessary for the body’s resistance and response to infections, cancers, and other foreign substances. The implications for nurses related to infections and malignancies include recognizing subtle and sometimes altered responses to infections and diseases in older adults. Educating older adults about the importance of participating in cancer screenings and maintaining immunizations throughout life is essential (see Chapters 8 and 19).

Folic Acid

Folic acid is one of the eight B vitamins that make up the B-complex group. Folic acid is a water-soluble vitamin that functions as a coenzyme, which means it is inactive unless linked to an enzyme. Folic acid is necessary for the normal functioning of RBCs and WBCs. A decrease in folic acid can indicate protein-energy malnutrition, macrocytic anemia, megaloblastic anemia, and liver and renal disease. Alcohol and various other drugs are known to interfere with the absorption of folate. Some drugs have also been shown to decrease folic acid levels. These include anticonvulsants, antimalarials, and methotrexate (Pagana & Pagana, 2003). However, the effect of aging on folate is still debatable because of variance in defining the lower limits of “normal” and the different methods used to determine folate levels (Gilleece & Dexter, 2002).

Because of the relationship of nutrition and alcohol consumption to folic acid levels, it is important for the gerontologic nurse to assess clients regarding their nutritional intake, including alcohol consumption habits. Elevated levels of folic acid may be seen in people with pernicious anemia, who do not have an adequate amount of B₁₂ to metabolize folic acid. Therefore the folic acid test should be done in conjunction with assessments for vitamin B₁₂ levels (Pagana & Pagana, 2004).

Vitamin B₁₂

Another of the water-soluble vitamins that makes up the B-complex group and acts as a coenzyme is vitamin B₁₂, or cobalamin. Although changes in B₁₂ levels are seen in many older adults, some scientists do not believe that aging affects the ileal absorption of B₁₂ (Hall & Wiley, 1999). They state that problems with B₁₂ tend to be the result of diseases and other conditions such as gastric achlorhydria, pernicious anemia, pancreatic insufficiency, and ileal disease, each of which has much greater impact on B₁₂ absorption than aging alone (Hall & Wiley, 1999).

Malabsorption of B₁₂ can be caused by the effect of antibodies on gastric parietal cells and a decrease in intrinsic factor, the underlying cause of pernicious anemia. The prevalence of pernicious anemia increases significantly with aging (Chatta & Lipschitz, 1999).

B₁₂ is important for normal erythrocyte maturation (McCance & Huether, 2008) and acts as a coenzyme with folic acid. The synthesis of nucleic acids, and therefore the structure of deoxyribonucleic acid (DNA), depends on adequate B₁₂ intake (Grodner, Long, & DeYoung, 2004). Vitamin B₁₂ deficiency can lead to degeneration of the dorsal and lateral spinal columns, which in turn can lead to paresthesias of the feet and fingers and progression to spastic ataxia (Gaspard, 2002). Low B₁₂ levels may also lead to fatigue, weakness, and altered mental status. The combination of vitamin B₁₂, B₆, and folate tends to reduce the levels of homocysteine, thereby decreasing the risk of coronary artery disease (Grodner, Long, & DeYoung, 2004).

Total Iron Binding Capacity

Total iron binding capacity (TIBC) measures the amount of iron and the amount of available transferrin in the serum (McCance & Huether, 2008). Transferrin is a major transport protein responsible for the transport of iron in the body. Transferrin is a protein in the plasma that collects iron and transports it to the bone marrow for incorporation into hemoglobin. Increased TIBC and transferring levels may indicate iron deficiency anemia; decreased levels may indicate anemia of chronic disease.

Iron

Iron is found in the hemoglobin of the RBCs. When iron-containing foods are ingested, the iron is absorbed by the small intestine and transported to the plasma (Pagana & Pagana, 2003). Iron is necessary for controlling protein synthesis in the mitochondria and generating energy in the cells (Freedman & Sutin, 2002). Serum iron levels show progressive decreases in both genders with advancing age, although the ability to absorb iron appears to remain intact (Hall & Wiley, 1999). Iron deficiency anemia is the most common form of anemia seen in older adults. However, in spite of the decreases in serum iron levels seen with aging, anemia in older adults is not a normal consequence of aging. The gerontologic nurse should assess older adults for a lack of iron-containing foods in their diets, occult or chronic blood loss, and poor absorption of iron (Ahluwalia et al, 2004).

Uric Acid

Uric acid is a product of metabolism, specifically purine catabolism. Uric acid is excreted by the kidneys. Age-related changes in uric acid levels are significantly different between the genders. Because estrogen is thought to promote the excretion of uric acid, elevated levels are rarely seen in women before the onset of menopause (McCance & Huether, 2008).

Problems with uric acid may be a result of faulty excretion (e.g., kidney failure), overproduction of uric acid, or the presence of other substances that compete for excretion sites (e.g., ketoacids) (Pagana & Pagana, 2004). Elevated uric acid levels are seen in clients with gout. Gout is a common condition in older adults involving a disturbance in the body’s control of uric acid production or excretion. Excess uric acid accumulates in the body’s fluids, especially the blood and synovial fluids, forming crystals at high concentrations. These crystals deposit in the connective tissue of the body causing painful, inflamed joints. Thiazide diuretics, caffeine, low-dose aspirin, and antiparkinsonian drugs are also a common cause of increased uric acid levels in older adults (Pagana & Pagana, 2004).

Prothrombin Time

Prothrombin is a plasma protein that is converted to thrombin in the first step of the clotting cascade. Clotting is necessary to prevent the loss of vital body fluids that occurs when blood vessels rupture (Thibodeau & Patton, 2003). In addition to measuring prothrombin time (PT), health care professionals also measure the effectiveness of the activity of fibrinogen and coagulation factors V, VII, and X. The results of the PT laboratory test also reveal how effectively the vitamin K–dependent coagulation factors of the extrinsic and common pathways of the coagulation cascade are performing (McCance & Huether, 2008). An increased PT is seen in liver disease, vitamin K deficiency, bile duct obstruction, and salicylate intoxication. Some medications can also cause an increase in a patient’s PT. They are allopurinol, cephalothins, cholestyramine, clofibrate, and sulfonamides (Pagana & Pagana, 2003). Pagana and Pagana (2003) also report that digitalis and diphenhydramine can cause a decreased PT level.

Older adults are often prescribed the drug warfarin (Coumadin) after open-heart surgery and in cases of chronic atrial fibrillation. Warfarin interferes with the production of vitamin K–dependent coagulation factors, thereby decreasing the chance of thrombus formation. Warfarin can interact with many medications, especially those often taken by older adults, such as aspirin, quinidine, sulfa, indomethacin, and nonsteroidal antiinflammatory drugs (NSAIDs) (Pagana & Pagana, 2003). Gerontologic nurses should help clients understand the importance of keeping their appointments for PT checks and consulting their health providers before taking any medications not prescribed. The adequacy of warfarin therapy can be assessed by following a client’s PT level. The PT value is traditionally reported in seconds and includes a value called the international normalized ratio (INR). INR is a mathematic “correction” of the results of the one-stage PT and was created to standardize results caused by the variation in reagents. The INR should be between 2.0 and 3.0 for most thrombosis and embolus conditions and between 3.0 and 4.5 for clients with a history of recurrent thromboembolism or mechanical heart valves (O’Neill, 2002) (see Nutritional Considerations Box and Chapter 10 for in-depth information on nutrition).

Partial Thromboplastin Time

Partial thromboplastin time (PTT) refers to the measurement of the common pathway of clot formation. Heparin can inactivate prothrombin, so the PTT is a good indicator of whether an older adult is receiving adequate anticoagulation therapy. The effect of heparin on the body is faster than that of warfarin, but the effects are shorter. Nursing considerations include monitoring for bleeding and correct administration of the heparin dosage.

Erythrocyte Sedimentation Rate

The erythrocyte sedimentation rate (ESR) test measures the time that RBCs take to settle in normal saline over 1 hour. The measured values are reported in millimeters. The test does not relate to one specific condition or disorder but does indicate the presence of inflammation, so it is useful in monitoring the course of inflammatory activity in commonly occurring rheumatic diseases such as polymyalgia rheumatica, temporal arteritis, and rheumatoid arthritis. In addition, when the test is performed with a white cell count, an elevation can indicate infection. Kane, Ouslander, and Abrass (1999) state that mild elevations of 10 to 20 mm/hr in the ESR may be age related. Other scientists report that elevations as high as 30 to 35 mm/hr above normal adult values may be seen, even though no evidence of inflammatory disorders is present. This makes interpretation of the results of this test in older adults difficult

without other clinical data and makes it harder to consider differential diagnoses (Calkins, 1999).

C-Reactive Protein

C-reactive protein (CRP) is a marker present in the acute phase of an inflammatory response (Gambino, 1997). Said to be an earlier indicator than the ESR of any acute processes present in the body (SmithKline Beecham, 1998), CRP is useful to researchers in assessing clients with cardiovascular disease, myocardial infarction, and organ transplants, as well as those recovering from surgical procedures (Gambino, 1997; Oltrona et al, 1997; SmithKline Beecham, 1998). Smith et al (1995) concluded that a persistently high CRP or rising CRP level suggests the failure of antibiotic treatment or the development of a complicated bacterial infectious process. Although still a relatively underused and undervalued test to many practitioners, the CRP is now being examined for its value in place of the ESR in detecting many inflammatory conditions (Gambino, 1997; SmithKline Beecham, 1998).

Platelets

Platelets are small, irregular bodies, also known as thrombocytes, which are essential for clotting. They are formed in the bone marrow and stored in the spleen. When an injury occurs to a blood vessel, platelets are released and become “sticky,” forming a plug at the site and helping to trigger a cascade of other clotting functions (Thibodeau & Patton, 2003).

Platelets are important for normal body functioning because of their essential part in normal blood clotting. Decreases in platelet counts (to less than 100,000/mm³) require investigation. In one condition, known as myelodysplastic syndrome (MDS), pancytopenia is noted in more than half the clients diagnosed. Pancytopenia is when the levels of RBCs, WBCs, and platelets are all below normal. More than 50% of the cases found are in adults older than the age of 70. Treatment usually consists of transfusions with red cells or platelets, although most older adults will die of other disorders rather than MDS. This condition has been known to progress to acute leukemia (Gilleece & Dexter, 2002). At platelet levels below 20,000/mm³, the nurse should observe for spontaneous bleeding. If the client’s levels are 40,000/mm³ or below, prolonged bleeding after procedures can occur (Pagana & Pagana, 2003).

In assessing clients for potential or hidden blood losses, nurses have traditionally questioned clients about the color and consistency of their bowel movements. The gerontologic nurse, however, must recognize that older adults who take iron supplements have changes in bowel habits and stool color that may not necessarily indicate the passage of occult blood. When preparing older adults for fecal occult blood testing, it is important to instruct them to stop iron supplements 3 days before testing.