Clinical Chemistry/urinalysis Midterm from BOC, Harr, Elsevier and Tietz Questions and Answers Graded A

Clinical Chemistry/urinalysis Midterm from BOC, Harr, Elsevier and Tietz Questions and Answers Graded A The major intracellular cation is? Potassium Which electrolytes is the chief plasma cation whose main function is maintaining osmotic pressure? Sodium Which of the following enzymes catalyzes the conversion of p-nitrophenyl phosphate to a colored p-nitrophenol product? a. AST b. ALT c. ALP d. GGT c. Alkaline phosphatase (ALP) belongs to a group of enzymes that catalyze the hydrolysis of phosphate esters in an alkaline medium. ALP catalyzes the conversion of p-nitrophenyl phosphate to a colored p-nitrophenol product. Which of the following is most likely to produce an elevated plasma potassium result? a. Hypoparathyroidism b. Cushing's syndrome c. Diarrhea d. Hemolysis d. Hemolysis is the most common cause of hypercalcemia. A physician calls to request a CK test on a sample already in the laboratory for coagulation studies. The sample is 1 hour old and has been stored at 4 deg. c. The plasma shows very slight hemolysis. What is the best course of action and the reason for it? a. Perform the CK assay because no interferent is present b. Reject the sample because it is slightly hemolyzed c. Reject the sample because it has been stored too long d. Reject the sample because the citrate will interfere d. The recommended sample of choice for analysis of creatinine kinase (CK) is serum or heparin plasma. Anticoagulants other than heparin may inhibit CK activity Which of the following statements regarding CK is true? a. Levels are unaffected by strenuous exercise b. Levels are unaffected by repeated intramuscular injections c. Highest levels are seen in Duchenne's muscular dystrophy d. The enzyme is highly specific for heart injury c. Creatine kinase (CK) is an enzyme found in the heart, brain, skeletal muscle, and other tissues. Increased amounts of CK are released in the blood when muscle damage occurs, such as the muscle damage seen in acute myocardial infarction and Duchenne's muscular dystrophy Which of the following enzymes is the best indicator of pancreatic function? a. AST b. ALT c. GGT d. Lipase d. Lipase and amylase are both markers of pancreatic function; however, lipase is considered more specific because it remains elevated longer in acute pancreatitis Kinetic enzymatic assays are best performed during which phase of an enzymatic reaction? a. Linear phase b. Lag phase c. Plateau phase d. Any phase as long as temperature and pH are constant a. Enzyme assays are recommended to be performed during the linear phase, so that a consistent change over time can be used to calculate the enzyme concentration A nurse calls the laboratory technologist on duty asking about blood collection for the analysis of enzymes (AST, ALP, ALT, GGT, CK). Which of the following tubes would you suggest the technologist collect? a. Red top b. EDTA c. Oxalate d. Fluoride a. The best tube to use for testing these enzymes is a red-top tube. The other anticoagulants may cause issues with some of the enzyme assays. Which of the following enzymes catalyzes the conversion of starch to glucose and maltose? a. Lipase b. Amylase c. ALT d. GGT b. Amylase is an enzyme that can degrade complex carbohydrate molecules such as starch. Which of the following buffer systems is the most important physiologic buffer system in the body? a. Hemoglobin b. Protein c. Phosphate d. Bicarbonate/carbonic acid d. The bicarbonate-carbonic acid buffer system is the most important physiologic buffering system in the body, because it is the buffer system that immediately counteracts carbon dioxide normally produced by cell metabolism. Hepatocellular damage may be best assessed by which of the following parameters? a. Serum AST and ALT levels b. GGT and ALP c. Bilirubin, GGT, and ALP d. Ammonia and urea a. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are the most sensitive markers of hepatocellular damage. g-Glutamyltransferase (GGT) and alkaline phosphatase (ALP) are markers of hepatobiliary damage. Ammonia, although it may be seen in severe cases of liver damage, is not a sensitive marker