Clin Chem Final Flashcards

In a patient with suspected primary hyperthyroidism associated with Graves' disease, one would expect the following laboratory serum results: T4 _____; TSH ______ Increased, normal Increased, increased Normal, increased Decreased, normal Increased, decreased

The major fraction of organic iodine circulating in the blood is: Triiodothyronine Thyroglobulin Tetraiodothyronine Diiodotyrosine

During pregnancy, serum TBG concentration _____, total thyroid hormone levels are _____, and free thyroid hormone levels are _____ Is unaffected, increased, increased Decreases, decreases, unaffected Is unaffected, decreased, decreased Increases, increased, unaffected

Which one of the following statements about T3 is FALSE? It may be elevated to a greater extent than T4 in hyperthyroidism. It is thought to be the most active thyroid hormone. It is commonly decreased in patients with nonthyroidal illness. It is not bound to serum proteins.

The old T3 resin uptake test has been replaced by a direct assay for: Thyroglobulin Bound T3 Binding capacity of thyroxine-binding globulin Circulating free T3 Thyroxine-binding globulin

A two-year-old child with a decreased serum T4 is described as being somewhat dwarfed, stocky, and overweight and having coarse features. Of the following, the most informative additional laboratory test would be serum: Triiodothyronine (T3) Thyroid-stimulating hormone (TSH) Thyroxine-binding globulin (TBG) Cholesterol

What tests are used as part of newborn screening programs to identify congenital hypothyroidism? T4 and/or TSH T3 and/or T4 fT3 and/or T4 T3 and/or TSH

The TRH (thyrotropin releasing hormone) stimulation test is useful in differentiating hypothalamic hypothyroidism from: Pituitary hypothyroidism Sub-clinical hypothyroidism Primary hypothyroidism Hashimoto's thyroiditis

True or false? When taken by a euthyroid individual, oral contraceptives will have an increasing effect on thyroxine binding globulin. True False

True or false? Individuals taking recurring regimens of androgens or anabolic steroid drugs may exhibit increased TBG levels. True False

The primary physiological regulator of parathyroid hormone (PTH) synthesis and secretion is: PTH stimulating hormone. PTH releasing hormone from the pituitary gland. The concentration of free calcium in blood or extracellular fluid. The concentration of PTH in blood.

Hypoparathyroidism is most commonly caused by: Adenoma of the parathyroid gland. Pseudohypoparathyroidism. Parathyroid gland destruction. Resistance to parathyroid hormone.

What makes up the organic matrix component of bone? Cells and collagen only Calcium, protein, and collagen Minerals and cells only Cells only

In bone: Osteoblasts are the bone-forming cells. Osteoclasts are responsible for bone formation. Calcium is complexed with bicarbonate. The collagen component is type II collagen.

An individual’s serum phosphate level is decreased but his physician cannot determine a physiological basis for this abnormal result. What could possibly have caused this result? Individual not fasting when blood was drawn Specimen hemolysis Use of IV carbohydrate therapy to stimulate insulin secretion Diurnal variation

Hypercalcemia occurs in humoral hypercalcemia of malignancy (HHM) because: Tumors synthesize parathyroid hormone (PTH), which increases calcium levels in blood. Osteoclasts bind tumor marker proteins and the process of bone remodeling becomes unregulated. Metastasizing cells synthesize calcium and release it into the circulation. PTH-related protein (PTHrP) is synthesized by tumors and stimulates bone resorption.

The clinical usefulness of calcitonin measurement is: In the assessment of primary hyperparathyroidism. The differential diagnosis of multiple endocrine neoplasia (MEN). As a tumor marker for medullary thyroid carcinoma. In the determination of sources of vitamin D deficiency.

Which one of the following diseases is characterized by a loss in bone mass? Osteomalacia Bone cancer Rickets Osteoporosis

Which one of the following analytes is most useful in distinguishing primary from secondary hyperparathyroidism? Vitamin D Serum calcium Serum phosphorus Parathyroid hormones Parathyroid hormone

A factor that would alter protein binding of calcium and its redistribution among the three plasma pools would be: Liver disease. A change in an individual’s posture. Increased citrate concentration. An altered anion gap.

What causes the total thyroxine (T4) levels to be increased in pregnant women? Change in thyroglobulin synthesis Inappropriate iodine metabolism Altered glucose metabolism hCG-induced thyrotoxicosis

Which one of the following is not a function of the thyroid hormones? Increasing cholesterol synthesis and breakdown Control of metabolic rate Removal of defective RBCs Stimulation of neural development

Another term used to describe hyperthyroidism is: Cretinism. Euthyroid sick syndrome. Thyrotoxicosis. Goiter.

Severe hypothyroidism that develops during the newborn period is referred to as: Euthyroid sick syndrome. Thyrotoxicosis. Cretinism. Myxedema.

The limited clinical information that is available from the results of a total T4 measurement is due to: Interferences with circulating autoantibodies directed against the colloid. The fact that total T4 measurements reflect inactive, protein-bound hormone. The formation of fibrin clots during the preparation of the blood sample. The fact that circadian rhythms are not determined.

A woman with thyroid cancer has her thyroglobulin (Tg) level checked to assess return of thyroid function following surgery. The Tg value was markedly decreased. Her physician calls the laboratory asking for an explanation of the result. You respond that: Thyroid cancer obliterates all colloid in the thyroid gland and therefore Tg will not be present in a blood sample. This is a typical value for someone with thyroid cancer and that Tg can be used as a tumor marker, so decreased values are better than increased values. Your laboratory uses a Tg assay that likely has been interfered with by Tg autoantibodies, which limits the accurate measurement of Tg. Tg is probably being interfered with by the immunoglobulins that are involved in the healing postsurgery process.

There is concern that the upper reference interval value for TSH is set too high to detect subtle hypothyroid disease. It is suggested that the upper reference interval value be reduced to what level to address this concern? 5.0 mU/L 2.0 mU/L 3.0 mU/L 4.0 mU/L

Which of the following thyroid hormones is considered to be the most active physiologically? DIT T3 MIT T4

Which of the following laboratory tests is most useful in distinguishing between hypothalamic and pituitary causes of thyroid dysfunction? T3 TRH stimulation test TSH T4

In patients with developing subclinical hyperthyroidism, TSH levels will likely be ____, and fT4 will likely be ____ Decreased, normal Increased, normal Decreased, increasedIncreased, decreased

After treatment with medication or radioactive iodine is initiated for hyperthyroidism, disease activity is best initially monitored with ___, because ______ will take several weeks or more to return to the reference interval. fT3 and fT4, TSH TSH, T4 and T3 Serum iodine, TSH TSH, fT3 and fT4

Which of the following thyroid hormones normally peak at 24 to 36 hours post-delivery in a newborn and gradually fall over the first 4 weeks of life? T3 fT4 All of the above Total T4

The following laboratory data are suggestive of which clinical situation? TSH – decreased; T4 – decreased; T3 – decreased; rT3 – increased Development of a goiter Hashimoto’s thyroiditis Euthyroid sick syndrome Graves’ disease

Given the following characteristics, which disease state is most likely? TSH – increased; fT4 – increased; fT3 – increased; T3RU – decreased; TSI – negative; TPO-ab – unlikely to be positive; Thyroid scan uptake – increased Primary hypothyroidism Graves’ disease Autoimmune thyroiditis Secondary hyperthyroidism

When free thyroxine cannot be measured directly, the free thyroxine index (FT4I) may be calculated by using which measured laboratory data? TSH and T4 T4 and T3 resin uptake TSH and T3 resin uptake T3 and T3 resin uptake

The T3 resin uptake test is used to measure: TSH Total T3 Free T3 Thyroxine binding globulin (TBG)

Which of the following forms of thyroxine would be the least available to tissue receptors? Thyroxine bound to albumin in the circulation Thyroxine free in the circulation Thyroxine bound to thyroxine-binding globulin in the circulation Thyroxine bound to prealbumin in the circulation

Increased TSH, decreased T3, and decreased T4 with the presence of goiter indicate: Pseudohypothyroidism. Tertiary hypothyroidism. Secondary hypothyroidism. Primary hypothyroidism.

What is required for normal thyroxine synthesis? TSH, iodine, and thyroglobulin Iodine and thyroid-binding globulin Iodine and thyroglobulin Iodine

The secretory unit of the thyroid gland is the: Colloid. Parafollicular cell. Thymus. Thyroid follicle.

Which amino acid residue of thyroglobulin is responsible for binding iodine in the formation of thyroid hormones? Phenylalanine Tyrosine Guanidine Histidine

Thyroid hormones exert influence in most areas of the body. How do thyroid hormones influence the heart? They influence the sensitivity of the heart to the sympathetic nervous system. They cause peripheral hemodynamic alterations that influence cardiac function. They affect cardiac gene expression. All of the above

A blood specimen is collected in a heparin-containing tube for calcium and magnesium determination. Upon centrifugation, the plasma appeared hemolyzed. How would this affect the magnesium value? There would be no effect on the magnesium value. The magnesium would be incorporated into the bilirubin molecule, leading to a false negative value. Because erythrocytes contain magnesium, hemolysis would increase its apparent value. The magnesium would form complexes with the hemoglobin and the results would indicate a false negative value.

When a drug concentration exceeds the available metabolic capacity of the body, what does the drug’s metabolism become dependent on? The health of the renal system The drug concentration itself The amount of metabolizing enzyme The number of doses given per hour

A carbonate salt of which drug is used to control manic-depressive disorders? Acetaminophen Digoxin Phenytoin Lithium

Which of the following could account for drug toxicity following a prescribed dose? Increased drug metabolism caused by central nervous system disease Using a different route of administration than is typically used for that drug Decreased renal elimination leading to increased free drug concentration Using a single drug as opposed to multiple drugs for treatment

The fraction of drug absorbed into a physiological system that is based on the amount of drug given is referred to as: Bioavailability. Steady state. Dosing. Volume of distribution.

If a drug is acidic in nature, which of the following proteins will it associate with primarily for transport and distribution? α1-Glycoprotein Lipoprotein All of the above Albumin

The therapeutic range of a drug is: Dependent on renal function. The range of concentrations at which there are no drug interactions. Dependent on the route of drug administration. The range of concentrations within which the drug is effective yet not toxic.

The period of time during which the concentration of a therapeutic drug decays by 50% is referred to as the drug’s: Half-life. Dosing curve. Volume of distribution. Subtherapeutic range.

The steady state of a drug is defined as the: Metabolism of a drug with a high hepatic extraction rate by the liver before it reaches the systemic circulation. Time required for one-half of an administered drug to be lost through metabolism and elimination. Point at which the body concentration of the drug is in equilibrium with the rate of dose administered and the rate of elimination. Action of one drug on another.

Respiratory alkalosis is a clinical feature of overdose ingestion of salicylate because: The central nervous system is stimulated to depress breathing. Salicylates enhance anaerobic glycolysis. Salicylates induce hyperventilation. Uncoupling of oxidative phosphorylation occurs in all cells.

An individual is found unconscious with two empty pill bottles nearby, one of aspirin and the other of phenobarbital. The best antidote for this type of double drug overdose would be: Hemodialysis. N-acetylcysteine. Forced alkaline diuresis. Atropine.

An anticonvulsant used to control tonic-clonic (grand mal) seizures is: Digoxin Acetaminophen Phenytoin Lithium

A drug that relaxes the smooth muscles of the bronchial passages is: Acetaminophen Lithium Theophylline Phenytoin

Which one of the following immunosuppressant prodrugs inhibits inosine monophosphate dehydrogenase (IMPDH) to reduce the pool of intracellular guanine nucleotides and arrest T-cell proliferation? Disopyramide Mycophenolate mofetil Tacrolimus Imipramine

A cardiac glycoside that is used in the treatment of congenital heart failure and arrhythmias by increasing the force and velocity of myocardial contraction is: Digoxin Acetaminophen Lithium Phenytoin

The main reason for suboptimal drug levels in therapeutic drug monitoring is: Patient noncompliance with dosage regimen Renal failure Liver failure Improper dosage prescribed

Bioavailability of a drug refers to the: Drug transformation Extent and rate at which the active drug reaches target tissues Availability for therapeutic administration Availability of the protein-bound fraction of the drug

A class III antiarrhythmic drug that acts by blocking potassium channels and that is used to manage atrial fibrillation is: Digoxin. Procainamide. Quinidine. Amiodarone.

Cocaine is subject to recreational abuse because it: Depresses the CNS but not the peripheral nervous system, depending on the blood ethanol concentration, to produce euphoria and decreased inhibition. Blocks dopamine reuptake at nerve synapses and prolongs the action of dopamine in the CNS, leading to feelings of euphoria. Increases the effect of peripheral and central cholinergic nervous systems to induce feelings of happiness. Has CNS depressant effects resulting in sedation and hypnosis, and increases growth hormone release.

A positive urine immunoassay screening test for a drug of abuse must be confirmed by: GC-MS. A more sensitive and specific immunoassay procedure. Electrophoresis. A spot test.

The laboratory method of analysis that is accurate and precise for very low concentrations of carbon monoxide is: Potentiometry. Spectrophotometry. Gas chromatography. Immunoassay.

The method of monitoring therapeutic drug concentrations that is replacing HPLC-based methods and is now considered to be the best technology for analysis of biological specimens with high specificity and fewer interferences is: Liquid chromatography–mass spectrometry/mass spectrometry. Spectrophotometry. Gas-liquid chromatography. High performance liquid chromatography.

For a therapeutic drug that has a short half-life, for example levetiracetam, when is the appropriate time to collect a blood sample for therapeutic drug assessment? At 8 AM, when liver metabolism is highest Immediately before a dose of the drug is given There is no specific time that is the best for blood collection. Immediately after a dose of the drug is given

The name given to the group of enzymes that are particularly involved in phase I metabolism of drugs and that involve reduction/oxidation or hydrolysis is: Cytochromes P-450. Urokinases. Glucuronyltransferases. Methyltransferases.

What is the major metabolite of acetaminophen that is formed in the liver? Sulfanilic acid Glucuronide Ascorbic acid Formic acid

In a clinical laboratory without gas chromatography instrumentation, the common method of choice used to measure ethanol in serum or plasma is a(n): Potentiometric measurement of changes in voltage potential across electrodes. Planar chromatography method combined with mass spectrometry. Immunoassay using antibodies directed against acetaldehyde. Enzymatic analysis using alcohol dehydrogenase and measurement of nicotinamide adenine dinucleotide (NADH) formation.

In the liver, methanol is metabolized by _____ to form _____ γ-glutamyltransferase; water Aldehyde dehydrogenase; acetic acid Methanol hydroxylase; acetaldehyde Alcohol dehydrogenase; formaldehyde

The laboratory method of analysis that is accurate and precise for very low concentrations of carbon monoxide is: Immunoassay. Potentiometry. Gas chromatography. Spectrophotometry.

In which one of the following specimen types is there a strong relationship between it and plasma free drug concentration, but the window of detection is short compared with that in a urine specimen? Hair SerumOral fluid Meconium

Which one of the following enzymes is inhibited by organophosphate or carbamate compounds, such as those found in pesticides? Alcohol dehydrogenase Acetylcholinesterase Alkaline phosphatase Amylase

A drug of abuse that stimulates the central nervous system by blocking dopamine reuptake and rapidly metabolizes to inactive benzoylecgonine and ecgonine methyl ester is: Heroin. Methamphetamine. Ethanol. Cocaine.

The most common laboratory method for detection, discrimination, and quantitation of alcohols in biological specimens is: HPLC. Immunoassay. Flame ionization gas chromatography (GC). Spectrophotometry.

In a chronic user of marijuana, the metabolite will remain in urine for what period of time? 3 to 4 months Up to 73 days 2 to 7 days 3 to 4 weeks

A type of drug test that is used to rule out the presence of drugs or to suggest the presence of a particular drug group and that has been replaced by rapid immunoassay tests is the ____ test. Spot Confirmatory Gas chromatography Forensic drug

A sympathomimetic drug that can be a drug of abuse but has legitimate pharmacologic use as a treatment for narcolepsy is: Marijuana. Diazepam. Amphetamine. Fentanyl.

Because of its rapid turnaround time, the laboratory method of choice used to screen urine samples for their opiate content is: Immunoassay. Liquid chromatography. Ferric chloride test. Gas chromatography.

Cocaine is subject to recreational abuse because it: Blocks dopamine reuptake at nerve synapses and prolongs the action of dopamine in the CNS, leading to feelings of euphoria. Has CNS depressant effects resulting in sedation and hypnosis, and increases growth hormone release. Increases the effect of peripheral and central cholinergic nervous systems to induce feelings of happiness. Depresses the CNS but not the peripheral nervous system, depending on the blood ethanol concentration, to produce euphoria and decreased inhibition.

The enzyme responsible for the metabolism of delta-9-tetrahydrocannabinol (THC) to its various metabolites is: CYP3A. Alcohol dehydrogenase. CYP2D6. Aldehyde dehydrogenase.

To recognize a poisoning pattern, groups of drugs with similar actions, symptoms, and clinical signs are examined. These common signs and symptoms are referred to as the: Metabolic pattern. Toxidrome. Pattern constellation. Toxin effect.

An example of a nonbenzodiazepine sedative-hypnotic that is used in drug-facilitated sexual assault that interacts with a subtype of the GABAA receptor complex is: Zolpidem. Chloral hydrate. γ-hydroxybutyrate. Diazepam.

Agents related to the anticholinergic toxidrome include all of the following except: Tricyclic antidepressants. Antihistamines. Organophosphates. Phenothiazines.

Which of the following is a major active metabolite of procainamide that must be monitored along with the parent drug? Glycinexylidide N-acetylprocainamide Disopyramide Procainamide does not have an active metabolite.

Which one of the following therapeutic drugs is used in the management of acute lymphoblastic leukemia and inhibits DNA synthesis by decreasing methylation of pyrimidine nucleotides and their synthesis? Cyclosporine Tacrolimus Methotrexate Mycophenolic acid

An individual who appears to be very inebriated is brought to a hospital emergency department by the police. Laboratory blood gas results indicate metabolic acidosis with an increased serum osmol gap, the presence of serum acetone, and many urine oxalate crystals. Which alcohol did this individual ingest? Ethylene glycol Isopropanol Ethanol Methanol

Which of the following best defines the term "solution"? A. A combination of two or more different chemical elements in which the atoms of the different elements are held together by chemical bonds B. A heterogeneous combination of two or more substances where the properties of each individual substance are absorbed by the other(s) C. A homogeneous mixture of two or more substances that do not chemically react with each other D. A mixture of two or more substances that results in a change in the molecular composition of each substance

A solution is composed of 1% sodium chloride and 0.5% potassium chloride in distilled water. Which substance(s) would be considered the solute? A. Potassium chloride B. Sodium chloride C. Potassium chloride and sodium chloride D. Water

A solution in which the solvent is water is referred to as A. aqueous. B. dissolved. C. liquid. D. soluble.

A vial of 3 mg silver chloride (AgCl) is poured into a flask containing 100 mL water and mixed. After 24 hours, 2.9 mg of silver chloride remains as a solid at the bottom of the flask. Which of the following terms best describes the ability of silver chloride to dissolve in water? A. Insoluble B. Partly soluble C. Soluble D. Sparingly soluble

What is the risk of reporting an incorrect concentration for a patient sample? A. Administration of an inappropriate drug B. Misdiagnosis of an illness C. Both of the above D. Neither of the above

The concentration of an aqueous glucose solution is noted as 25% glucose (w/v). What does this tell us about the amount of glucose in the solution? A. There are 0.25 grams of glucose in every 100 mL of solution. B. There are 2.5 grams of glucose in every 100 mL of solution. C. There are 25 grams of glucose in every 100 mL of solution. D. There are 250 grams of glucose in every 100 mL of solution.

The concentration of a sodium chloride (NaCl) solution is defined as 10% NaCl (w/w). What does this tell us about the amount of NaCl in the solution? A. There are 10 grams of NaCl in every 10% of solution. B. There are 10 grams of NaCl in every 100 grams of solution. C. There are 10 grams of NaCl in every 100 mL of solution. D. There are 10 grams of NaCl in every 100 ounces of solution.

A solution of aqueous ferric chloride has a concentration of 15 ppm. What does this tell us about the amount of ferric chloride in the solution? A. There are 15 grams of ferric chloride in every 1,000,000 grams of solution. B. There are 15 grams of ferric chloride in every 1,000,000 mL of solution. C. There are 15 mL of ferric chloride in every 1,000,000 mL of solution. D. Both A and B are correct.

When a concentration is expressed in terms of molarity, what does it tell us about the solution? A. The number of moles of a solute present in 1 liter of solution B. The number of moles of a solute present in 1,000 grams of solution C. The number of osmoles of a solute present in 1 liter of solution D. The number of osmoles of a solute present in 1,000 grams of solution

A solution of sodium chloride (NaCl) is calculated to be 0.5 M at 37°C. The solution was placed in an 18°C refrigerator for 24 hours and the molarity was recalculated. What would you expect the molarity of the solution to be? A. 0.5 M B. Greater than 0.5 M C. Less than 0.5 M D. It cannot be determined from the information given.

Consider the following equation: concentration of glucose = (8.5 moles glucose)/.1 kilogram) What are the units of the value calculated by this equation? A. Molal B. Molar C. v/v D. w/v

What does the term "equivalent weight" mean? A. The amount of a solute that is equivalent in mass to 1 mole of the intended solvent B. The amount of a substance that contains, theoretically combines with, or theoretically replaces 1 mole of hydrogen atoms C. The molality of a solute that contains the same number of atoms as 100 grams of solvent D. The molarity of a solute that is necessary to completely saturate 100 mL of solvent

What is the rule for determining an equivalent for calculating the normality of a base or salt solution? A. An equivalent is the number of hydrogen atoms present in the base or salt. B. An equivalent is the number of hydrogen ions with which it can theoretically combine. C. An equivalent is the total number of hydroxide (OH-) groups divided by the number of hydrogen atoms present. D. An equivalent is the total number of positively charged ions present in the molecule.

What is the specific gravity of a solution? A. The ratio of the concentration of a solute to the concentration of the solvent at 37°C B. The ratio of the concentration of a solute to the density of water at 4°C C. The ratio of the density of a solute to the density of the solvent at 37°C D. The ratio of the density of a solution to the density of water at 4°C