Understanding Normal Laboratory Values for Blood Components and Tests, Lecture notes of Nursing

Download Understanding Normal Laboratory Values for Blood Components and Tests and more Lecture notes Nursing in PDF only on Docsity! u11 Laboratory Values PYRAMID TERMS blood The liquid pumped by the heart through the arteries, veins, and capillaries. Blood is composed of a clear yellow fluid (plasma), formed elements, and cell types with different functions (Fig. 11-1). blood cell Any of the formed elements of the blood, including red cells (erythrocytes), white cells (leukocytes), and plate- lets (thrombocytes). plasma The watery, straw-colored, fluid part of lymph and the blood in which the formed elements (blood cells) are sus- pended. Plasma is made up of water, electrolytes, protein, glucose, fats, bilirubin, and gases and is essential for carry- ing the cellular elements of the blood through the circulation. serum The clear and thin fluid part of blood that remains after coagulation. Serum contains no blood cells, platelets, or fibrinogen. venipuncture Puncture into a vein to obtain a blood speci- men for testing; the antecubital veins are the veins of choice because of ease of access. THE PYRAMID TO SUCCESS This chapter identifies the normal adult values for the most common laboratory tests. It is important to remember that normal laboratory values may vary slightly, depending on the laboratory setting and equip- ment used in testing. If you are familiar with the normal values, you will be able to determine whether an abnor- mality exists when a laboratory value is presented in a question. The questions on the NCLEX-RN examination related to laboratory values will require you to identify whether the laboratory value is normal or abnormal, and then you are required to think critically about the effects of the laboratory value in terms of the client. Pyramid Points focus on knowledge of the normal values for the most common laboratory tests, therapeutic serum medication levels of commonly prescribed medi- cations, and determination of the need to implement specific actions based on the findings. When a question is presented on the NCLEX-RN examination regarding a specific laboratory value, note the disorder presented in the question and the associated body organ affected as a result of the disorder. This process will assist you in determining the correct answer. For example, if the ques- tion asks about the immune status of a client receiving chemotherapy, assessment of laboratory values will focus on the white blood cell (WBC) count and the neu- trophils. You will need to analyze these results as possi- bly being low and determine the specific client need, which in this case would be the risk for infection. In the client receiving chemotherapy who has a low WBC count, your plan centers on the immune system and protecting the client from infection. Implementa- tion focuses on preventive interventions related to infec- tion, perhaps protective isolation measures. Evaluation may focus on maintenance of a normal temperature in the client. Box 11-1 lists some of the common abbrevia- tions found in laboratory values. The Priority Nursing Actions box lists the steps needed for obtaining a blood sample. CLIENT NEEDS Safe and Effective Care Environment Applying principles of infection control Ensuring surgical asepsis when obtaining a specimen Implementing procedures for handling hazardous and infectious materials Maintaining standard, transmission-based, and surgical asepsis Obtaining informed consent for specific procedures Verifying the identity of the client Health Promotion and Maintenance Preparing the client for the laboratory test Discussing the importance of follow-up laboratory studies Identifying community resources available for the follow-up Implementing posttest procedures Describing specific interventions or home care mea- sures required based on the results114 Monitoring for signs and symptoms that indicate the need to notify the health care provider Psychosocial Integrity Communicating the purpose of the laboratory test to the client Communicating with the client regarding the labora- tory results Providing emotional support during testing Physiological Integrity Identifying normal values for the most common labo- ratory tests Identifying therapeutic serum medication levels of commonly prescribed medications Monitoring for clinical manifestations associated with an abnormal laboratory value Providing comfort measures Reporting significant laboratory values Determining the significance of an abnormal laboratory value and the need to implement specific actions based on the laboratory results Monitoring for potential complications related to a test Drawing blood specimens from an extremity in which an intravenous solution is infusing can pro- duce an inaccurate result. Prolonged use of a tourni- quet and clenching and unclenching the hand before venous sampling can increase the blood level of potassium, producing an inaccurate result. TOTAL BODY WEIGHT WHOLE BLOOD (percentage by volume) FORMED ELEMENTS (number per cubic mm) PLASMA (percentage by weight) Blood 8% Other fluids and tissues 92% Centrifuged sample of blood Buffy coat PLASMA 55% Platelets 150,000-400,000 Proteins 7% Water 91% Other solutes 2% Leukocytes 4,500-11,000 Neutrophils 60-70% Lymphocytes 20-25% Monocytes 3-8% Eosinophils 2-4% Basophils 0.5-1% Albumins 54% Globulins 38% Fibrinogen 4% Prothrombin 1% Ions Nutrients Waste products Gases Regulatory substances LEUKOCYTES PROTEINS Erythrocytes 4-6.2 million OTHER SOLUTES FORMED ELEMENTS 45% s FIGURE 11-1 Approximate values for the components of blood in a normal adult. (Modified from Thibodeau, G.A., & Patton, K.T. [2010]. The human body in health and disease [5th ed.]. St. Louis: Mosby.) tBox 11-1 Pyramid Abbreviations Abbreviation Definition g/dL grams per deciliter IU/L International units per liter mcg/dL micrograms per deciliter mcg/mL micrograms per milliliter mEq/L milliequivalents per liter mg/dL milligrams per deciliter microunits/mL microunits per milliliter mL/kg milliliters per kilogram mm3 millimeters cubed mm/hr millimeters per hour ng/mL nanograms per milliliter pg/mL picogram per milliliter units/L units per liter mL microliters s115CHAPTER 11 Laboratory Values 2. Value: 0 to 30 mm/hr, depending on age of client 3. Nursing consideration: Fasting is not necessary, but a fatty meal may cause plasma alterations. B. Hemoglobin and hematocrit 1. Description a. Hemoglobin is the main component of ery- throcytes and serves as the vehicle for trans- porting oxygen and carbon dioxide. b. Hemoglobin determinations are important in identifying anemia. c. Hematocrit represents RBC mass and is an important measurement in the identification of anemia or polycythemia (Table 11-2). 2. Nursing consideration: Fasting is not required. C. Serum iron 1. Description a. Iron is found predominantly in hemoglobin. b. Iron acts as a carrier of oxygen from the lungs to the tissues and indirectly aids in the return of carbon dioxide to the lungs. c. Iron aids in diagnosing anemias and hemo- lytic disorders. 2. Normal values a. Male adult: 65 to 175 mcg/dL b. Female adult: 50 to 170 mcg/dL 3. Nursing consideration: Level of iron will be in- creased if the client has ingested iron before the test. D. RBC count (erythrocytes) 1. Description a. RBCs function in hemoglobin transport, which results in delivery of oxygen to the body tissues. b. RBCs are formed by red bone marrow, have a life span of 120 days, and are removed from the blood via the liver, spleen, and bone marrow. c. The RBC count aids in diagnosing anemias and blood dyscrasias. d. The RBC count evaluates the ability of the body to produce RBCs in sufficient numbers. 2. Values a. Female adult: 4 to 5.5 million cells/mL b. Male adult: 4.5 to 6.2 million cells/mL 3. Nursing consideration: Fasting is not required. IV. SERUM ENZYMES AND CARDIAC MARKERS (Table 11-3) A. Creatine kinase (CK) 1. Description a. Creatine kinase is an enzyme found in muscle and brain tissue that reflects tissue catabolism resulting from cell trauma. b. The CK level begins to rise within 6 hours of muscle damage, peaks at 18 hours, and returns to normal in 2 to 3 days. c. The test for CK is performed to detect myo- cardial or skeletal muscle damage or central nervous system damage; a normal CK value is 26 to 174 units/L. d. Isoenzymes include CK-MB (cardiac), CK-BB (brain), and CK-MM (muscles). e. Isoenzyme CK-MB is found mainly in cardiac muscle, CK-BB is found mainly in brain tis- sue, and CK-MM is found mainly is skeletal muscle. TABLE 11-2 Normal Adult Blood Components Blood Component Normal Value HEMOGLOBIN Male adult 14-16.5 g/dL Female adult 12-15 g/dL HEMATOCRIT Male adult 42%-52% Female adult 35%-47% IRON Male adult 65-175 mcg/dL Female adult 50-170 mcg/dL RED BLOOD CELLS Male adult 4.5-6.2 million/mL Female adult 4-5.5 million/mL TABLE 11-3 Normal Adult Serum Enzymes/Cardiac Markers Serum Enzyme Normal Value Creatine kinase (CK) 26-174 units/L CK isoenzymes CK-MB 0%-5% of total CK-MM 95%-100% of total CK-BB 0% Lactate dehydrogenase 140-280 units/L Lactate dehydrogenase isoenzymes LDH1 14%-26% LDH2 29%-39% LDH3 20%-26% LDH4 8%-16% LDH5 6%-16% Troponin I <0.6 ng/mL; >1.5 ng/mL indicates myocardial infarction Troponin T >0.1-0.2 ng/mL indicates myocardial infarction Myoglobin <90 mcg/L; elevation could indicate myocardial infarction Atrial natriuretic peptides (ANP) 22 to 27 pg/mL Brain natriuretic peptides (BNP) Less than 100 pg/mL C-type natriuretic peptides (CNP) Not yet determined; reference range provided with results and should be reviewed s118 UNIT III Nursing Sciences 2. Values a. CK-MB: 0% to 5% of total b. CK-MM: 95% to 100% of total c. CK-BB: 0% 3. Nursing considerations a. If the test is to evaluate skeletal muscle, instruct the client to avoid strenuous physical activity for 24 hours before the test. b. Also instruct the client to avoid ingestion of alcohol for 24 hours before the test. c. Invasive procedures and intramuscular injec- tions may falsely elevate CK levels. B. Lactate dehydrogenase (LDH) 1. Description a. The LDH isoenzymes affected by acute myo- cardial infarction are LDH1 and LDH2. b. The LDH level begins to rise about 24 hours after myocardial infarction and peaks in 48 to 72 hours; thereafter, it returns to normal, usually within 7 to 14 days. c. The presence of an LDH flip (when LDH1 is higher than LDH2) is helpful in diagnosing a myocardial infarction. 2. Nursing considerations a. The LDH isoenzyme levels should be inter- preted in view of the clinical findings. b. Testing shouldbe repeatedon3consecutivedays. C. Troponins 1. Description a. Troponin is a regulatory protein found in stri- ated muscle (skeletal and myocardial). b. Increased amounts of troponins are released into the bloodstream when an infarction causes damage to the myocardium. c. Levels elevate as early as 3 hours after myocardial injury. Troponin I levels may remain elevated for 7 to 10 days and troponin T levels may remain elevated for as long as 10 to 14 days. d. Serial measurements are important to com- pare with a baseline test. 2. Values a. Troponin I: Value usually is lower than 0.6 ng/mL; value higher than 1.5 ng/mL is con- sistent with a myocardial infarction. b. Troponin T: Higher than 0.1 to 0.2 ng/mL is consistent with a myocardial infarction. 3. Nursing considerations a. Testing is repeated in 12 hours, followed by daily testing for 3 to 5 days. b. Rotate venipuncture sites. D. Myoglobin 1. Description a. Myoglobin is an oxygen-binding protein that is found in striated (cardiac and skeletal) muscle that releases oxygen at very low tensions. b. Any injury to skeletal muscle will cause a release of myoglobin into the blood. 2. Values: Normal value is lower than 90 mcg/L; an elevation could indicate myocardial infarction. 3. Nursing considerations a. The level can rise as early as 2 hours after a myocardial infarction, with a rapid decline in the level after 7 hours. b. Because the myoglobin level is not cardiac- specific and rises and falls so rapidly, its use in diagnosing myocardial infarction may be limited. E. Natriuretic peptides 1. Description a. Natriuretic peptides are neuroendocrine pep- tides that are used to identify clients with congestive heart failure (CHF). b. There are three major peptides: atrial natri- uretic peptides (ANP) synthesized in cardiac atrial muscle, brain natriuretic peptides (BNP) synthesized in cardiac ventricle mus- cle, and C-type natriuretic peptides (CNP) synthesized by endothelial cells c. BNP is the primary marker for identifying CHF as the cause of dyspnea. 2. Values: a. ANP: 22 to 27 pg/mL b. BNP: less than 100 pg/mL c. CNP: not yet determined 3. Nursing consideration: Fasting is not required. The higher the BNP level, the more severe the CHF. If the BNP is elevated the dyspnea is due to CHF; if it is normal the dyspnea is due to a pulmonary problem. V. SERUM GASTROINTESTINAL STUDIES A. Albumin 1. Description a. A main plasma protein of blood b. Maintains oncotic pressure and transports bilirubin, fatty acids, medications, hormones, and other substances that are insoluble in water c. Increased in conditions such as dehydration, diarrhea, and metastatic carcinoma; decreased in conditions such as acute infection, ascites, and alcoholism d. Presenceof detectable albumin, orprotein, in the urine is indicative of abnormal renal function 2. Value: 3.4 to 5 g/dL 3. Nursing consideration: Fasting is not required. B. Alkaline phosphatase 1. Description a. Alkaline phosphatase is an enzyme normally found in bone, liver, intestine, and placenta. s119CHAPTER 11 Laboratory Values b. The level rises during periods of bone growth, liver disease, and bile duct obstruction. 2. Value: 4.5 to 13 King-Armstrong units/dL 3. Nursing considerations a. The client may need to fast 12 hours before the test. b. Hepatotoxic medications administered within 12 hours before specimen collection can cause a falsely elevated value. c. Transport the specimen to the laboratory immediately. C. Ammonia 1. Description a. Ammonia is a byproduct of protein catabo- lism; most of it is created by bacteria acting on proteins present in the gut. b. Ammonia is metabolized by the liver and excreted by the kidneys as urea. c. Elevated levels resulting from hepatic dys- function may lead to encephalopathy. d. Venous ammonia levels are not a reliable indicator of hepatic coma. 2. Value: 10 to 80 mcg/dL 3. Nursing considerations a. Instruct the client to fast, except for water, and to refrain from smoking for 8 to 10 hours before the test; smoking increases ammonia levels. b. Place the specimen on ice and transport to the laboratory immediately. D. Alanine aminotransferase (ALT) 1. Description: Used to identify hepatocellular dis- ease of the liver and to monitor improvement or worsening of the disease. 2. Value: 4 to 6 international units/L 3. Nursing considerations a. Previous intramuscular injections may cause elevated levels. b. No fasting is required. E. Aspartate aminotransferase (AST) 1. Description: Used to evaluate a client with sus- pected hepatocellular disease (may also be used along with other cardiac markers to evaluate cor- onary artery occlusive disease) 2. Value: 0 to 35 units/L 3. Nursing considerations a. Previous intramuscular injections may cause elevated levels b. No fasting is required. F. Amylase 1. Description a. This enzyme, produced by the pancreas and salivary glands, aids in the digestion of com- plex carbohydrates and is excreted by the kidneys. b. In acute pancreatitis, the amylase level is greatly increased; the level starts rising 3 to 6 hours after the onset of pain, peaks at about 24 hours, and returns to normal in 2 to 3 days after the onset of pain. 2. Value: 25 to 151 units/L 3. Nursing considerations a. On the laboratory form, list the medications that the client has taken during the previous 24 hours before the test. b. Note that many medications may cause false- positive or false-negative results. c. Results are invalidated if the specimen was obtained less than 72 hours after cholecys- tography with radiopaque dyes. G. Lipase 1. Description a. This pancreatic enzyme converts fats and tri- glycerides into fatty acids and glycerol. b. Elevated lipase levels occur in pancreatic dis- orders; elevations may not occur until 24 to 36 hours after the onset of illness and may remain elevated for up to 14 days. 2. Value: 10 to 140 units/L 3. Nursing considerations: Endoscopic retrograde cholangiopancreatography (ERCP) may increase lipase activity. H. Bilirubin 1. Description a. Bilirubin is produced by the liver, spleen, and bone marrow and is also a byproduct of hemoglobin breakdown. b. Total bilirubin levels can be broken down into direct bilirubin, which is excreted pri- marily via the intestinal tract, and indirect bilirubin, which circulates primarily in the bloodstream. c. Total bilirubin levels increase with any type of jaundice; direct and indirect bilirubin levels help differentiate the cause of the jaundice. 2. Values a. Bilirubin, direct (conjugated): 0 to 0.3 mg/dL b. Bilirubin, indirect (unconjugated): 0.1 to 1 mg/dL c. Bilirubin, total: Lower than 1.5 mg/dL 3. Nursing considerations a. Instruct the client to eat a diet low in yellow foods, avoiding foods such as carrots, yams, yellow beans, and pumpkins, for 3 to 4 days before the blood is drawn. b. Instruct the client to fast for 4 hours before the blood is drawn. c. Note that results will be elevated with the ingestion of alcohol or the administration of morphine sulfate, theophylline, ascorbic acid (vitamin C), or acetylsalicylic acid (aspirin). d. Note that results are invalidated if the client has received a radioactive scan within 24 hours before the test. s120 UNIT III Nursing Sciences 2. Value: 1.6 to 2.6 mg/dL 3. Nursing considerations a. Prolonged use of magnesium products causes increased serum levels. b. Long-term parenteral nutrition therapy or exces- sive loss of body fluidsmaydecrease serum levels. C. Phosphorus 1. Description a. Phosphorus is important in bone formation, energy storage and release, urinary acid-base buffering, and carbohydrate metabolism. b. Phosphorus is absorbed from food and is excreted by the kidneys. c. High concentrations of phosphorus are stored in bone and skeletal muscle. 2. Value: 2.7 to 4.5 mg/dL 3. Nursing considerations: Instruct the client to fast before the test. IX. THYROID STUDIES A. Description 1. Thyroid studies are performed if a thyroid disor- der is suspected. 2. Thyroid studies help differentiate primary thyroid disease from secondary causes and from abnor- malities in thyroxine-binding globulin levels. B. Values 1. Thyroid-stimulating hormone (also called thyro- tropin): 0.2 to 5.4 microunits/mL 2. Thyroxine (T4): 5 to 12 mcg/dL 3. Thyroxine, free (FT4): 0.8 to 2.4 ng/dL 4. Triiodothyronine (T3): 80 to 230 ng/dL C. Nursing consideration: Test results may be invalid if the client has undergone a radionuclide scan within 7 days before the test. X. WHITE BLOOD CELL COUNT A. Description 1. WBCs function in the immune defense system of the body. 2. The WBC count assesses leukocyte distribution. B. Value: 4500 to 11,000 cells/mm3 (Table 11-5) C. Nursing considerations 1. A “shift to the left” means that an increased number of immature neutrophils is present in the blood. 2. A low total WBC count with a left shift indicates a recovery from bone marrow depression or an infection of such intensity that the demand for neutrophils in the tissue is higher than the capacity of the bone marrow to release them into the circulation. 3. A high total WBC count with a left shift indi- cates an increased release of neutrophils by the bone marrow in response to an overwhelming infection or inflammation. 4. A “shift to the right” means that cells have more than the usual number of nuclear segments; found in liver disease, Down syndrome, and megaloblastic and pernicious anemia. Monitor the WBC count closely in clients receiving chemotherapy because of the risk for neutropenia. XI. HEPATITIS TESTING A. Description 1. Tests include radioimmunoassay, enzyme-linked immunosorbent assay (ELISA), and microparti- cle enzyme immunoassay. 2. Serological tests for specific hepatitis virus markers assist in defining the specific type of hepatitis. B. Values 1. The presence of immunoglobulin M (IgM) anti- body to hepatitis A virus and the presence of the total antibody to hepatitis A virus identify the disease. 2. Detection of hepatitis B core antigen (HBcAg), envelope antigen (HBeAg), and surface antigen (HBsAg), or their corresponding antibodies, constitutes hepatitis B assessment. 3. Hepatitis C is confirmed by the presence of anti- bodies to hepatitis C virus. 4. Serological hepatitis D virus determination is made by detection of the hepatitis D antigen (HDAg) early in the course of the infection and by detection of anti–hepatitis D virus antibody in the later disease stages. 5. Specific serological tests for hepatitis E virus include detection of IgM and IgG antibodies to hepatitis E. 6. Hepatitis G virus has been found in some blood donors (donated blood), IV drug users, hemodi- alysis clients, and clients with hemophilia; how- ever, hepatitis G virus does not appear to cause significant liver disease. C. Nursing consideration: If the radioimmunoassay technique is being used, the injection of radionu- clides within 1 week before the blood test is per- formed may cause falsely elevated results. TABLE 11-5 Normal Adult White Blood Cell Differential Count Cell Type Count Neutrophils 1800-7800 cells/mm3 Bands 0-700 cells/mm3 Eosinophils 0-450 cells/mm3 Basophils 0-200 cells/mm3 Lymphocytes 1000-4800 cells/mm3 Monocytes 0-800 cells/mm3 s123CHAPTER 11 Laboratory Values XII. HUMAN IMMUNODEFICIENCY VIRUS (HIV) AND ACQUIRED IMMUNODEFICIENCY SYNDROME (AIDS) TESTING A. Description 1. Testing detects HIV, which is the cause of AIDS. 2. Common tests used to determine the presence of antibodies to HIV include ELISA, Western blot, and immunofluorescence assay (IFA). 3. A single reactive ELISA test by itself cannot be used to diagnose HIV and should be repeated in duplicate with the same blood sample; if the result is repeatedly reactive, follow-up tests using Western blot or IFA should be performed. 4. A positive Western blot or IFA result is consid- ered confirmatory for HIV. 5. A positive ELISA result that fails to be confirmed by Western blot or IFA should not be considered negative, and repeat testing should take place in 3 to 6 months. B. CD4þ T-cell counts 1. Monitors the progression of HIV 2. As the disease progresses, usually the number of CD4þ T-cells decreases, with a resultant decrease in immunity. 3. Normal CD4þ T-cell count is between 500 and 1600 cells/L. 4. Generally, the immune system remains healthy with CD4þ T-cell counts higher than 500 cells/L. 5. Immune system problems occur when the CD4þ T-cell count is between 200 and 499 cells/L. 6. Severe immune system problems occur when the CD4þ T-cell count is lower than 200 cells/L. C. CD4-to-CD8 ratio 1. Monitors progression of disease. 2. Normal ratio is approximately 2:1. D. Viral culture involves placing the infected client’s blood cells in a culture medium and measuring the amount of reverse transcriptase activity over a specified period of time. E. Viral load testing measures the presence of HIV viral genetic material (RNA) or another viral protein in the client’s blood. F. The p24 antigen assay quantifies the amount of HIV viral core protein in the client’s serum. G. Oral testing for HIV 1. Uses a device that is placed against the gum and cheek for 2 minutes 2. Fluid (not saliva) is drawn into an absorbable pad, which, in an HIV-positive individual, con- tains antibodies. 3. The pad is placed in a solution and a specified observable change is noted if the test result is positive. 4. If the result is positive, a blood test is needed to confirm the results. H. Home test kits for HIV 1. In one at-home test kit, a drop of blood is placed on a test card with a special code num- ber; the card is mailed to a laboratory for testing for HIV antibodies. 2. The individual receives the results by calling a special telephone number and entering the spe- cial code number; test results are then given. I. Nursing considerations 1. Maintain issues of confidentiality surrounding HIV and AIDS testing. 2. Follow prescribed state regulations and proto- cols related to reporting positive test results. XIII. URINE TESTS (Table 11-6) XIV. THERAPEUTIC SERUM MEDICATION LEVELS (Table 11-7) TABLE 11-6 Normal Adult Values: Urine Tests Name of Test Value Color Pale yellow Odor Specific aromatic odor, similar to ammonia Turbidity Clear pH 4.5-7.8 Specific gravity 1.016 to 1.022 Glucose <0.5 g/day Ketones None Protein None Bilirubin None Casts None to few Crystals None Bacteria None or <1000/mL Red blood cells <3 cells/HPF White blood cells "4 cells/HPF Chloride 110-250 mEq/24 hr Magnesium 7.3-12.2 mg/dL Potassium 25-125 mEq/24 hr Sodium 40-220 mEq/24 hr Uric acid 250-750 mg/24 hr HPF, High-powered field. s124 UNIT III Nursing Sciences MORE QUESTIONS ON THE CD! Practice Questions 63. A client with atrial fibrillation who is receiving maintenance therapy of warfarin sodium (Couma- din) has a prothrombin time (PT) of 35 seconds. Based on the prothrombin time, the nurse antici- pates which of the following prescriptions? 1. Adding a dose of heparin sodium 2. Holding the next dose of warfarin 3. Increasing the next dose of warfarin 4. Administering the next dose of warfarin 64. The nurse checks the laboratory result for a serum digoxin level that was prescribed for a client earlier in the day and notes that the result is 2.4 ng/mL. The nurse should take which immediate action? 1. Notify the physician. 2. Check the client’s last pulse rate. 3. Record the normal value on the client’s flow sheet. 4. Administer the next dose of the medication as scheduled. 65. A client has been admitted to the hospital for uri- nary tract infection and dehydration. The nurse determines that the client has received adequate volume replacement if the blood urea nitrogen level drops to: 1. 3 mg/dL 2. 15 mg/dL 3. 29 mg/dL 4. 35 mg/dL 66. A client arrives in the emergency room complain- ing of chest pain that began 4 hours ago. A tropo- nin T blood specimen is obtained, and the results indicate a level of 0.6 ng/mL. The nurse deter- mines that this result indicates: 1. A normal level 2. A low value that indicates possible gastritis 3. A level that indicates a myocardial infarction 4. A level that indicates the presence of possible angina 67. A client is receiving a continuous intravenous infusion of heparin sodium to treat deep vein thrombosis. The client’s activated partial throm- boplastin (aPTT) time is 65 seconds. The nurse anticipates that which action is needed? 1. Discontinuing the heparin infusion 2. Increasing the rate of the heparin infusion 3. Decreasing the rate of the heparin infusion 4. Leaving the rate of the heparin infusion as is 68. A client with a history of cardiac disease is due for a morning dose of furosemide (Lasix). Which serum potassium level, if noted in the client’s lab- oratory report, should be reported before adminis- tering the dose of furosemide? 1. 3.2 mEq/L 2. 3.8 mEq/L 3. 4.2 mEq/L 4. 4.8 mEq/L 69. A client with a history of gastrointestinal bleeding has a platelet count of 300,000 cells/mm3. The nurse should take which action after seeing the laboratory results? TABLE 11-7 Therapeutic Serum Medication Levels Medication Therapeutic Range Acetaminophen (Tylenol) 10-20 mcg/mL Amikacin (Amikin) 25-30 mcg/mL Amitriptyline 120-150 ng/mL Carbamazepine (Tegretol) 5-12 mcg/mL Chloramphenicol (Chloromycetin) 10-20 mcg/mL Desipramine (Norpramin) 150-300 ng/mL Digoxin (Lanoxin) 0.5-2 ng/mL Disopyramide (Norpace) 2-5 mcg/mL Ethosuximide (Zarontin) 40-100 mcg/mL Gentamicin 5-10 mcg/mL Imipramine (Tofranil) 150-300 ng/mL Lidocaine (Xylocaine) 1.5-5 mcg/mL Lithium (Lithobid) 0.5-1.2 mEq/L Magnesium sulfate 4-7 mg/dL Phenobarbital (Luminal) 10-30 mcg/mL Phenytoin (Dilantin) 10-20 mcg/mL Propranolol (Inderal) 50-100 ng/mL Salicylate 100-250 mcg/mL Theophylline 10-20 mcg/mL Tobramycin (Nebcin) 5-10 mcg/mL Valproic acid (Depakene) 50-100 mcg/mL s125CHAPTER 11 Laboratory Values