Clinical Chemistry MCQ 0% 20 Created by clinicalsci Clinical Chemistry MCQ Welcome to the Clinical Chemistry Multiple Choice Questions test. You have 30 minutes to answer 30 questions. Lets begin, Good Luck!! 1 / 30 Which of the following statements regarding serum urea is true? BUN is elevated in prerenal as well as renal failure Levels are independent of diet BUN rises earlier and quicker than creatinine in renal damage High BUN levels can result from necrotic liver disease Blood urea nitrogen (BUN) and creatinine are con sidered markers of kidney function. Renal failure can cause elevations in BUN and other prerenal conditions such as dehydration or a high-protein diet that raise levels of BUN without affecting creatinine levels. 2 / 30 A plasma glucose result is 100 mg/dL. The corresponding glucose in whole blood would approximate: 98 mg/dL 114 mg/dL 87 mg/dL 58 mg/dL Whole blood glucose levels are 12% to 15% lower than plasma glucose levels. Therefore a plasma glucose level of 100 mg/dL would roughly correspond to a whole blood level of 85 mg/dL. 3 / 30 Which of the following blood gas disorders is most commonly associated with an abnormal anion gap? Respiratory alkalosis Metabolic acidosis Metabolic alkalosis Respiratory acidosis The anion gap, especially when elevated, is useful in diagnosing the type of metabolic acidosis and in indicating if a mixed disorder exists. 4 / 30 The VLDL fraction primarily transports what substance? Triglyceride Chylomicron Phospholipid Cholesterol The VLDL fraction is primarily composed of triglycerides and lesser amounts of cholesterol and phospholipids. Protein components of VLDL are mostly apolipoprotein B-100 and apolipoprotein C. VLDL migrates electrophoretically in the prebeta region. 5 / 30 Which of the following enzymes is the best indicator of pancreatic function? AST GGT Lipase ALT Lipase and amylase are both markers of pancreatic function; however, lipase is considered more specific because it remains elevated longer in acute pancreatitis. 6 / 30 Hepatocellular damage may be best assessed by which of the following parameters? Serum AST and ALT levels Bilirubin, GGT, and ALP GGT and ALP Ammonia and urea Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are the most sensitive markers of hepatocellular damage.gamma-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 of hepatocellular damage. 7 / 30 In a healthy individual, which protein fraction has the greatest concentration in serum? Albumin gamma-globulin beta-globulin alpha1-globulin The serum proteins are divided into five principal fractions based on their electrophoretic mobilities. The five fractions are albumin, alpharglobulin, alpha2-globulin, beta-globulin, and gamma-globulin. Albumin constitutes the largest individual fraction of the serum proteins. The reference concentration of albumin in serum ranges between 3.5 and 5.0 g/dL, and the total globulin concentration is between 2.3 and 3.5 g/dL. 8 / 30 Which of the following instruments is used in the clinical laboratory or in reference laboratories to detect beta and gamma emissions? Fluorometer Spectrophotometer Nephelometer Scintillation counter Radionuclides are quantified by measuring the amount of energy that they emit. This can be in the form of alpha emission (4/2)He^2+, beta emission(electrons ejected from the nucleus of a radioisotope during radioactive decay), or gamma emission (electromagnetic radiation emitted during radioactive decay). Beta and gamma emissions can be detected by scintillation counters. The sensing element of a scintillation counter is a fluor, a substance capable of converting radiation energy to light energy. 9 / 30 Which enzyme is common to all enzymatic methods for triglyceride measurement? Glycerol phosphate oxidase Pyruvate kinase Glycerol kinase Glycerol phosphate dehydrogenase All enzymatic methods to measure triglycerides, regardless of the enzyme used, begin with the conversion of triglycerides to glycerol and fatty acids in the presence of the enzyme lipase, followed by the conversion of glycerol to glycerol-3-phosphate in the presence of the enzyme glycerol kinase. 10 / 30 Which of the following enzymes catalyzes the conversion of starch to glucose and maltose? ALT Lipase Amylase GGT Amylase is an enzyme that can degrade complex carbohydrate molecules such as starch. 11 / 30 The main estrogen produced by the ovaries and used to evaluate ovarian function is: Estradiol Epiestriol Estrogen Estriol Estrogens are a group of steroids responsible for the development of female sex organs. The estrogens include estrone, estradiol, and estriol. Estradiol is the predominant form of estrogen. 12 / 30 When free thyroxine cannot be measured directly, the free thyroxine index (FT4I) may be calculated by using which measured laboratory data? TSH and T3 resin uptake TSH and T4 T3 and T3 resin uptake T4 and T3 resin uptake The free thyroxine (FT4) index is calculated as follows: FT4I = TT4 x Thyroid hormone binding ratio/100 13 / 30 A patient's total cholesterol/HDL cholesterol ratio is 10.0. What level of risk for coronary heart disease does this result indicate? No risk Twice average risk Average risk Half average risk Both total cholesterol and HDL cholesterol are independent measurable indicators of risk of coronary heart disease (CHD). By relating total and HDL cholesterol in a mathematical way, physicians can obtain valuable additional information in predicting risk for CHD. Risk of CHD can be quantified by the ratio of total cholesterol to HDL cholesterol along the following lines: Ratio Risk CHD 3.43 half average 4.97 average 9.55 two times average 24.39 three times average Thus this patient shows approximately twice the average risk for CHD. Risk ratios for CHD can easily be calculated by instrument and/or laboratory computers given the total and HDL cholesterol values. Reports indicating level of risk based on these results can be programmed by the laboratory and/or manufacturer. 14 / 30 Osmolality can be defined as a measure of the concentration of a solution based on: The density of particles present The isoelectric point of a particle The number of particles present The number and size of particles present Osmolality and specific gravity both measure the solute concentration of a solution. Specific gravity measures solute concentration as the solute’s density, which is subject to interference from large molecules such as glucose and proteins. Osmolality, on the other hand, measures solute concentration as the number of molecules present by measuring the number of molecules per kilogram of water. 15 / 30 Which of the following apoproteins is inversely related to risk for coronary heart disease and is a surrogate marker for HDL? APO E Apo B Apo A-I Apo B100 Apo A-I is the predominant apoprotein associated with the high-density lipoprotein (HDL) molecule, activates (lecithin cholesterol acyltransferase[LCAT]), and is associated with reverse cholesterol transport. As a result, it is protective against coronary artery disease. 16 / 30 Which of the following changes will occur with a blood gas sample exposed to room air? pH increased pO2 decreased Ionized calcium increased pCO2 increased Room air contains a pO2 of 150 mm Hg and a pCO2 of approximately zero. When a blood gas sample is received in the laboratory uncapped or if it contains air bubbles, gas equilibration between the air and the blood will occur, causing a decreased pCO2, increased pO2, and increased pH. Blood gas samples from a patient without oxygen supplementation with a pO2 greater than 110 mm Hg should be investigated for air contamination. 17 / 30 When measuring K+ with an ion-selective electrode by means of a liquid ion exchange membrane, what antibiotic will be incorporated into the membrane? Valinomycin Monactin Streptomycin Nonactin The ion-exchange electrode is a type of potentiometric, ion-selective electrode that consists of a liquid ion-exchange membrane that is made of an inert solvent and an ion-selective neutral earner material. A collodion membrane may be used to separate the membrane solution from the sample solution being analyzed. Because of its ability to bind K+, the antibiotic valinomycin is used as the neutral carrier for the K+ selective membrane. The antibiotics non actin and monactin are used in combination as the neutral carrier for the NH^-selective membrane. A special formulation is used to make a selective glass membrane for the measurement of sodium. 18 / 30 Which of the following reagents can be used to measure protein in cerebrospinal fluid? Ponceau S Biuret Coomassie brilliant blue Bromcresol green The concentration of total protein in cerebrospinal fluid (CSF) is 15^5 mg/dL. Such a low level of protein requires a method with sufficient sensitivity such as Coomassie brilliant blue. Turbidimetric methods can also be used to quantify protein in CSF. Neither biuret nor Ponceau S has the sensitivity needed, and bromcresol green measures only albumin and does not react with the globulins. 19 / 30 In spectrophotometric analysis, what is the purpose of the reagent blank? Correct for interfering chromogens Correct for color contribution of the reagents Correct for lipemia Correct for protein The reagent blank contains the same reagents as those used for assaying the specimen. By adjusting the spectrophotometer to IOQ%T (or 0 absorbance) with the reagent blank, the instrument automatically subtracts the color contributed by the reagents from each succeeding reading of specimens, controls, and standards. This technique is used both in manual procedures and automated instruments. Because the reagent blank does not contain sample, there is no correction for interfering chromogens or lipemia. 20 / 30 Identification of which of the following is useful in early stages of glomerular dysfunction? Urinary light chains Microalbuminuria Hematuria Ketonuria In renal disease, glomerular or tubular malfunction results in proteinuria. In early stages of glomerular dysfunction, small quantities of albumin will appear in the urine. Because the concentration is so low, urine dipstick assays are unable to detect the presence of such a small quantity of albumin; hence the term "microalbuminuria." Annual testing of diabetic individuals for microalbuminuria is recommended, because identification of these low levels of albumin that precede nephropathy would allow for clinical intervention to control blood glucose levels and blood pressure. The reference interval for urinary albumin is less than 30 mg/day. Microalbuminuria may be quantified using immunonephelometry and enzyme immunoassay. 21 / 30 Checking instrument calibration, temperature accuracy, and electronic parameters are part of: Quality control Precision verification Preventive maintenance Function verification As part of a good quality assurance program, a laboratory should perform function verification, performance verification, and preventive maintenance for all instrument systems. Function verification is the monitoring of specific instrument functions and the correcting of these functions when necessary to assure reliable operation. Function verification includes monitoring temperature, setting electronic parameters, calibrating instruments, and analyzing quality control data. It is important that performance of these activities be properly documented. 22 / 30 Which of the following conditions will elevate ionized calcium? Acidosis Diabetes mellitus Alkalosis Hyperlipidemia In a state of acidosis there is an increased amount of hydrogen ions that combine with albumin. Because H ions are combining with albumin, less albumin is available to bind to calcium; therefore ionized calcium levels increase. 23 / 30 Which of the biochemical processes below is promoted by insulin? Uptake of glucose by the cells Gluconeogenesis Esterification of cholesterol Glycogenolysis Insulin lowers glucose levels by increasing the uptake of glucose into the cell and through increased glucose metabolism. 24 / 30 Increased PCO2 in a patient most commonly results in which of the following primary acid-base abnormalities? Metabolic alkalosis Respiratory acidosis Respiratory alkalosis Metabolic acidosis PCO2 is an acidic gas controlled by the lungs (respiratory system) and when in increased concentrations will cause respiratory-driven acidosis. 25 / 30 Which of the following techniques can be used to quantify apolipoproteins? Spectrophotometric endpoint Ion-selective electrode Refractometry Immunonephelometric assay A number of immunochemical assays can be used to quantify the apolipoproteins. Some of the techniques that can be used include immunonephelometric assay, enzyme-linked immunosorbent assay (ELISA), and immunotur bidimetric assay. Commercial kits are available for the quantification of Apo A-I and Apo B-100. Measuring the apolipoproteins can be of use in assessing increased risk for coronary heart disease. 26 / 30 What endogenous substance may cause a positive interference in the urease/glutamate dehydrogenase assay? Glucose Ammonia Creatinine Cholesterol Adequate specificity is generally obtained when using the urease/glutamate dehydrogenase method. Because urease hydrolyzes urea to ammonia and water, a positive interference from endogenous ammonia will occur with elevated blood levels of ammonia. Such interference may occur from use of aged blood specimens and in certain metabolic diseases. 27 / 30 What does an increase in the serum enzyme levels indicate? Increased glomerular filtration rate Tissue damage and necrosis Accelerated enzyme production Decreased enzyme catabolism The majority of serum enzymes that are of interest clinically are of intracellular origin. These enzymes function intracellularly, with only small amounts found in serum as a result of normal cellular turnover. Increased serum levels are due to tissue damage and necrosis, where the cells disintegrate and leak their contents into the blood. Thus, elevated serum levels of intracellular enzymes are used diagnostically to assess tissue damage 28 / 30 The kidney is responsible for acid-base balance through the removal of H ions via four major mechanisms. Which of the following describes one of those mechanisms? Reaction of H ions with Na in the descending loop of Henle Reaction of H ions with ADH in the collecting ducts Reabsorption of H ions in the proximal convoluted tubule Reaction of H ions with filtered bicarbonate ions The kidney is responsible for acid-base balance through the removal of H ions via (1) the reaction of the hydrogen ions with bicarbonate, (2) the reaction of hydrogen ions with filtered buffers such as disodium salt, (3) reaction with ammonia, and (4) excretion of the free hydrogen ions. 29 / 30 Which of the following sets of tests would Which of the following sets of tests would be the most useful in diagnosing an AMI? CK-MB, troponin, myoglobin LDH, troponin, myoglobin LDH, CK-MB, troponin AST, LDH, CK-MB The clinical usefulness of AST and LDH has been replaced primarily by cardiac troponin and to a lesser degree by myoglobin, whereas CK isoenzymes continue to play a role. Although myoglobin will increase above the upper reference interval in 1-3 hours following AMI, it is not tissue specific for cardiac muscle and its application has found limited usefulness. Myoglobin will also be increased following skeletal muscle trauma. Troponin I and troponin T have proven to be useful markers, because each has a cardiac-specific isoform, cTnl and cTnT. cTnl appears to be more specific for cardiac muscle, because it has not been identified in regenerating or diseased skeletal muscle, whereas cTnT is made in small amounts by skeletal muscle. Total CK is elevated in AMI and takes 4-6 hours to rise above the upper reference interval. 30 / 30 What is the immediate precursor of bilirubin formation? Verdohemoglobin Urobilinogen Mesobilirubinogen Biliverdin In the catabolic process of hemoglobin degradation, the alpha-carbon methene bridge of the tetrapyrrole ring structure of heme opens oxidatively to form verdohemoglobin. Verdohemoglobin is a complex composed of biliverdin, iron, and the protein globin. This complex then undergoes degradation in which iron is removed and returned to the body iron stores, the globin portion is returned to the amino acid pool, and the biliverdin undergoes reduction to form bilirubin. It is biliverdin, therefore, that is the immediate precursor of bilirubin formation. Mesobilirubinogen and urobilinogen represent intestinal breakdown products of bilirubin catabolism. Please enter your Name and Email to to view your results and answers. NameEmail Your score is The average score is 51%Share your score ! Facebook Twitter 0% Restart quiz