Elsevier (Clinical Chemistry)

Question 1

(1) Which of the following is considered a lipid?

a. Chylomicrons
b. LDL
c. Cholesterol
d. HDL

Answer 1

c. Cholesterol

Chylomicrons, low-densitylipoprotein (LDL), and high-density lipoprotein (HDL) are considered to be lipoproteins that transport lipids throughout the body; cholesterol is classified as a lipid.

Question 2

(2) In the laboratory procedure for the quantification of HDL, the purpose of the dextran sulfate is to:

a. Precipitate all Apo A1 containing lipoproteins
b. Covert cholesterol esters to cholesterol for detection
c. Precipitate all Apo B and Apo A containing lipoproteins
d. Precipitate all Apo B containing proteins

Answer 2

d. Precipitate all Apo B containing proteins

Dextran sulfate precipitates all Apo B–containing lipoproteins (chylomicrons, very-low-density lipoprotein [VLDL], intermediate density lipoprotein [IDL], and low-density lipoprotein [LDL]) leaving high-density lipoprotein (HDL) (Apo A–containing lipoprotein) in the supernatant. HDL is then mixed with the reagent cholesterol esterase and cholesterol oxidase to quantitate HDL concentrations.

Question 3

(3) Which of the following lipoproteins is the smallest of all the lipoproteins and is composed of 50% protein?

a. HDL
b. Chylomicrons
c. LDL
d. Triglycerides

Answer 3

a. HDL

Lipoproteins are characterized by size and density. High-density lipoprotein (HDL) is the smallest, most dense lipoprotein, carrying 50% of its weight as protein.

Question 4

(4) Which of the following would be most adversely affected by a nonfasting sample?

a. HDL
b. LDL
c. Cholesterol
d. Triglycerides

Answer 4

d. Triglycerides

Triglycerides are most adversely affected by recent food intake, and therefore a fast is always recommended for triglyceride analysis.

Question 5

(5) Which of the following apoproteins is responsible for receptor binding for IDL and the chylomicron remnant produced in fat transport?
a. Apo A1
b. Apo C
c. Apo E
d. Apo B

Answer 5

c. Apo E

Apo E is a ligand for the low-density lipoprotein (LDL) receptor, reverses cholesterol transport, and is a regulator of cell growth and immune responses.

Question 6

(6) Which of the following enzymes is found bound to HDL and LDL in blood plasma and acts to convert free cholesterol into cholesteryl esters?

a. Cholesterol esterase
b. Cholesterol oxidase
c. Lecithin-cholesterol acyltransferase
d. Lipase

Answer 6

c. Lecithin-cholesterol acyltransferase

Two enzymes are responsible for esterifying cholesterol, lecithin cholesterol acyl transferase (extracellular), and acetyl coenzyme A (acylCoA) cholesterol acyltransferase (intracellular).

Question 7

(7) Which of the following blood samples would serve best to assay lipoproteins because this anticoagulant acts to preserve lipoproteins?

a. EDTA plasma sample
b. Heparin plasma sample
c. Citrate plasma sample
d. Fluoride plasma sample

Answer 7

a. EDTA plasma sample

Although lipoproteins can be assayed using a variety of anticoagulants, the preferred anticoagulant is ethylenediaminetetraacetic acid (EDTA) because it preserves lipoproteins over time.

Question 8

(8) Exogenous triglycerides are transported in the plasma in which of the following forms?

a. VLDL
b. Chylomicrons
c. LDL
d. Cholesteryl esters

Answer 8

b. Chylomicrons

Triglycerides are transported throughout the body by means of two lipoproteins: very-low-density lipoprotein (VLDL) and chylomicrons. VLDL carries endogenously derived triglycerides, and chylomicrons carry exogenously derived triglycerides.

Question 9

(9) A patient presents to his physician for a lipid profile. The following results are received:

HDL = 50 mg/dL
Total cholesterol = 300 mg/dL
Triglycerides = 200 mg/dL

The calculated LDL cholesterol is:

a. 200
b. 210
c. 290
d. 350

Answer 9

b. 210

Low-density lipoprotein (LDL) cholesterol is calculated as follows:
LDL = TC - ( HDL + TG/5)
LDL = 300 - (50 + 200/5)
LDL = 300 - 90
LDL = 210 mg/dL

Question 10

(10) According to the National Cholesterol Education Program, which lipid or lipoprotein class is more important for therapeutic decision making (diet and medication decisions)?

a. Chylomicrons
b. LDL
c. HDL
d. Cholesterol

Answer 10

b. LDL

Low-density lipoprotein (LDL) is currently the only lipoprotein or lipid that is recommended for use by physicians for therapeutic lifestyle changes.

Question 11

(11) Which of the following mechanisms accounts for the elevated plasma level of b-lipoproteins seen in hyperbetalipoproteinemia (Fredrickson’s type II lipoproteinemia)?

a. Elevated insulin found in these patients
b. Apo B-100 receptor defect
c. Apo C-II–activated lipase deficiency
d. LCAT deficiency

Answer 11

b. Apo B-100 receptor defect

Both forms of hyperbetalipoproteinemia (types IIA and IIB) are due to either a defect in the low-density lipoprotein (LDL) receptor (type IIA) or a defect in Apo B-100 (type IIB).

Question 12

(12) Which enzyme is common to all enzymatic methods for triglyceride measurement?

a. Glycerol phosphate oxidase
b. Glycerol phosphate dehydrogenase
c. Pyruvate kinase
d. Glycerol kinase

Answer 12

d. Glycerol kinase

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.

Question 13

(13) A patient sample is assayed for fasting triglycerides and a triglyceride value of 1036 mg/dL. This value is of immediate concern because of its association with which of the following conditions?

a. Coronary heart disease
b. Diabetes
c. Pancreatitis
d. Gout

Answer 13

c. Pancreatitis

Marked increases in triglyceride levels, between 1000 and 2000 mg/dL have been associated with increased risk for the development of pancreatitis.

Question 14

(14) Which of the following apoproteins is inversely related to risk for coronary heart disease and is a surrogate marker for HDL?

a. Apo A-I
b. Apo B
c. Apo B100
d. APO E

Answer 14

a. Apo A-I

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.

Question 15

(15) What is the most appropriate fasting procedure when a lipid study of triglycerides, total cholesterol, HDL, and LDL tests are ordered?

a. 8 hours, nothing but water allowed
b. 10 hours, water, smoking, coffee, tea (no sugar or cream) allowed
c. 12 hours, nothing but water allowed
d. 16 hours, water, smoking, coffee, tea (no sugar or cream) allowed

Answer 15

c. 12 hours, nothing but water allowed

The recommended fasting state for the study of lipids involves nothing but water for 12 hours before the blood sample collection.

Question 16

(16) John Smithers (21 years of age) is in to see his physician for a pre-college physical and checkup. John has always been extremely healthy. The following laboratory results are received:

AStandard = 0.679
AControl = 0.650
ASmithers = 0.729
CStandard = 200 mg/dL
Control range 190-195 mg/dL

John’s cholesterol concentration is approximately:
a. 186 mg/dL
b. 199 mg/dL
c. 209 mg/dL
d. 215 mg/dL

Answer 16

c. 209 mg/dL

Using Beer’s law, the concentration of cholesterol in the patient (Smithers) serum is determined as follows: 0.679

Concentration cholesterol = Absorbance unknown / Absorbance standard x Concentration standard
Concentration cholesterol = 0.729/0.679 x 200 mg/dL
Concentration cholesterol = 209 mg/dL

[ANSWER IS FROM ELSEVIER; UNCLEAR]

Question 17

(17) Sucrose is considered a disaccharide that on hydrolysis yields which of the following sugars?

a. Glucose
b. Galactose and glucose
c. Maltose and glucose
d. Fructose and glucose

Answer 17

d. Fructose and glucose

Sucrose upon hydrolysis yields fructose and glucose.

Question 18

(18) Laboratory tests are performed for a postmenopausal, 57 year-old woman as part of an annual physical examination. The patient’s random serum glucose is 220 mg/dL, and the glycated hemoglobin (HbA1c) is 11%. Based on this information, this patient would mostly likely be classified as:

a. Normal
b. Impaired
c. Having type 1 diabetes
d. Having type 2 diabetes

Answer 18

d. Having type 2 diabetes

According to the American Diabetes Association criteria for the diagnosis of diabetes (below), this patient would most likely be classified as having type 2 diabetes.

Symptoms and a random plasma glucose ≥ 200 mg/dL or
Fasting plasma glucose ≥ 126 mg/dL or
2-hr OGTT ≥ 200 mg/dL or
Hbg A1c ≥ 6.5%

Question 19

(19) Which of the biochemical processes below is promoted by insulin?

a. Glycogenolysis
b. Gluconeogenesis
c. Esterification of cholesterol
d. Uptake of glucose by the cells

Answer 19

d. Uptake of glucose by the cells

Insulin lowers glucose levels by increasing the uptake of glucose into the cell and through increased glucose metabolism

Question 20

(20) Laboratory results for a patient with type 2 diabetes are as follows:

Glucose: 128 mg/dL
Total Cholesterol: 195 mg/dL
HDL: 45 mg/dL
LDL: 105 mg/dL
BUN: 38 mg/dL
Creatinine: 2.1 mg/dL
Microalbuminuria: 54 ug/Ml
AST: 28 U/L
ALT: 38 U/L

Which of the following statements is correct regarding this
patient?

a. Patient is at increased risk for cardiovascular disease
b. Patient is at increased risk for diabetic nephropathy
c. Patient is at increased risk for liver failure
d. Patient is at risk for hypoglycemia

Answer 20

b. Patient is at increased risk for diabetic nephropathy

The data presented indicate that the glucose and low-density lipoprotein (LDL) are mildly elevated, and the blood urea nitrogen (BUN), creatinine, and microalbuminuria results are moderately elevated. This information together indicates that the patient is at most risk for the development of diabetic nephropathy.

Question 21

(21) At what serum glucose concentration would glucose begin to appear in the urine?

a. 50 mg/dL
b. 75 mg/dL
c. 100 mg/dL
d. 170 mg/dL

Answer 21

d. 170 mg/dL

The renal threshold for glucose is 160 to 180 mg/dL. Once plasma levels of glucose hit that threshold, it will spill over into the urine.

Question 22

(22) Which of the following laboratory tests is the best marker to detect patients with diabetes who are at risk for developing diabetic nephropathy?

a. Creatinine
b. BUN
c. Microalbuminuria test
d. Glucose

Answer 22

c. Microalbuminuria test

Blood urea nitrogen (BUN) and creatinine are markers of kidney function; however, they are not sensitive enough markers to detect early diabetic nephropathy. The best test to use to detect diabetic nephropathy is the microalbuminuria test.

Question 23

(23) A 68-year-old obese woman visits her doctor reporting increased urination (especially at night), increased thirst, and increased appetite. Her glucose on examination was 210 mg/dL (fasting). Which of the following statements best fits with the given information above?

a. The patient most likely has type 1 diabetes mellitus
b. The patient would show a positive glucose in her urine
c. The patient would have a decreased glycated hemoglobin
d. Additional testing of this patient should include assessment of hypoglycemia

Answer 23

b. The patient would show a positive glucose in her urine

An obese, elderly patient with report of increased urination at night, increased thirst, and increased appetite is indicative of a diagnosis of diabetes, most likely type 2 diabetes in this case. With the patient being 68 years of age and obese with only mildly elevated levels of glucose, the diagnosis of type 1 is unlikely. Patients with diabetes would have increased glycated hemoglobin. With a fasting glucose of 210 mg/dL, the assessment of hypoglycemia is unwarranted.

Question 24

(24) Which of the following hemoglobin A1c results represents an impaired state according to the American Diabetes Association?

a. 4.5%
b. 5.5%
c. 6.0%
d. 6.5%

Answer 24

c. 6.0%

According to the American Diabetes Association, A1c results between 5.7% and 6.4% indicate an impaired state (prediabetes).

Question 25

(25) A plasma glucose result is 100 mg/dL. The corresponding glucose in whole blood would approximate:

a. 58 mg/dL
b. 87 mg/dL
c. 98 mg/dL
d. 114 mg/dL

Answer 25

b. 87 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.

Question 26

(26) Which of the following methods is virtually specific for glucose and employs G6PD as a second coupling step requiring magnesium?

a. Hexokinase
b. Glucose oxidase
c. Glucose dehydrogenase
d. Pyruvate kinase

Answer 26

a. Hexokinase

Of the three methods to measure glucose, glucose oxidase, hexokinase, and glucose dehydrogenase, the hexokinase method is considered virtually specific for glucose.

Question 27

(27) A 62-year-old patient presents to the physician with report of increased thirst and increased urination, particularly at night. The physician requests a series of tests over the next few days. The following data are received:

Random glucose: 186 mg/dL
Fasting glucose: 114 mg/dL
2-Hour OGTT: 153 mg/dL
HbA1c: 5.9%

Which of the following conclusions may be made regarding these data?

a. Data represents normal glucose status
b. Data represents an impaired glucose status
c. Data represents the presence of an insulinoma
d. Data represents the diagnosis of diabetes

Answer 27

b. Data represents an impaired glucose status

The cutoff points for normal, impaired, and diagnostic states are described below. According to the values below, the data suggest an impaired state.

NORMAL:
Resting plasma glucose: <200 mg/dL
Fasting plasma glucose: <100 mg/dL
2-Hr OGTT: <200 mg/dL
A1c: <5.7%

IMPAIRED:
Resting plasma glucose: 140-199 mg/dL
Fasting plasma glucose: 100-125 mg/dL
2-Hr OGTT: 140-199 mg/dL
A1c: 5.7%-6.4%

DIAGNOSTIC:
Resting plasma glucose: ≥ 200 mg/dL
Fasting plasma glucose: ≥ 126 mg/dL
2-Hr OGTT: ≥ 200 mg/dL
A1c: ≥6.5%

Question 28

(28) Which of the following renal conditions is associated with a recent group A b-hemolytic streptococcus infection?

a. Kidney obstruction
b. Acute renal failure
c. Uremic syndrome
d. Acute glomerulonephritis

Answer 28

d. Acute glomerulonephritis

Acute glomerulonephritis is often associated with a recent group A b-hemolytic Streptococcus infection. It is hypothesized that immune complex development associated with a group A b hemolytic Streptococcus infection directly injures the glomerular basement membrane of the glomerulus.

Question 29

(29) The red complex developed in the Jaffe method to determine creatinine measurements is a result of the complexing of creatinine with which of the following?

a. Alkaline picrate
b. Diacetyl monoxide
c. Sulfuric acid
d. Sodium hydroxide

Answer 29

a. Alkaline picrate

The classic Jaffe reaction involves complexing of creatinine with an alkaline picrate solution to produce a red complex (Janovski complex).

Question 30

(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?

a. Reabsorption of H ions in the proximal convoluted tubule
b. Reaction of H ions with Na in the descending loop of Henle
c. Reaction of H ions with filtered bicarbonate ions
d. Reaction of H ions with ADH in the collecting ducts

Answer 30

c. 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.

Question 31

(31) Given the data below, the calculated creatinine clearance corrected for body surface area approximates __________.

Serum creatinine: 1.2 mg/dL
Urine creatinine: 120 mg/dL
Urine volume: 1.75 L/day
Surface area: 1.80 m^2

a. 16 mL/min
b. 115 mL/min
c. 126 mL/min
d. 210 mL/min

Answer 31

b. 115 mL/min

[[Urine creatinine (mg/dL) x Urine volume (mL/min] / Serum creatinine (mg/dL)]] x (1.73 m^2 / Surface area of patient)

Urine volume: 1.75 L/day x 1000 mL/1 L x 1 hr/60 min = 1.22 mL/min

= [(120 mg/dL x 1.22 mL/min) / 1.2 mg/dL] x (1.73 m^2 / 1.80 m^2) = 117 mL/min

Question 32

(32) Which formula is most accurate in predicting plasma osmolality?

a. Na + 2(Cl) +BUN +Glucose
b. 2(Na) + 2 (Cl) +Glucose + BUN
c. 2(Na) +Glucose/18 +BUN/2.8
d. 2(BUN) +Glucose/18 + Cl/2.8

Answer 32

c. 2(Na) +Glucose/18 +BUN/2.8

2 Sodium (mmol/L) +Glucose mg/dL/18 +Blood
urea nitrogen (BUN) mg/dL/2.8

Question 33

(33) Which of the following statements regarding serum urea is true?

a. Levels are independent of diet
b. High BUN levels can result from necrotic liver disease
c. BUN is elevated in prerenal as well as renal failure
d. BUN rises earlier and quicker than creatinine in renal damage

Answer 33

c. BUN is elevated in prerenal as well as renal failure

Blood urea nitrogen (BUN) and creatinine are considered 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.

Question 34

(34) Osmolality can be defined as a measure of the concentration of a solution based on:

a. The number of particles present
b. The number and size of particles present
c. The density of particles present
d. The isoelectric point of a particle

Answer 34

a. The number 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.

Question 35

(35) An increased osmole gap is most commonly seen in which of the following?

a. Type 2 diabetes
b. Pancreatitis
c. Presence of toxins such as ethanol and ethylene glycol
d. Liver failure

Answer 35

c. Presence of toxins such as ethanol and ethylene glycol

The osmolal gap (difference between calculated and measured osmolality) when increased is indicative of the presence of osmotically active substances present other than sodium, blood urea nitrogen (BUN), and glucose. Other osmotically active substances may include ethanol, methanol, ethylene glycol, lactate, or b-hydroxybutyrate.

Question 36

(36) A patient with type 2 diabetes is in for a routine examination with the physician. A series of laboratory tests are performed, including calculation of an eGFR. The patient’s calculated eGFR is 64 mL/min. This result is most indicative of:

a. A normal state
b. Abnormal glucose control
c. Mild kidney damage
d. Kidney failure

Answer 36

c. Mild kidney damage

According to the National Kidney Foundation, a glomerular filtration rate of 60 to 89 indicates mild kidney damage.

Question 37

(37) A healthy 28-year-old female sees her physician for a routine examination and receives a “relatively” clean bill of health except for the results below.

Total bilirubin 2.8 mg/dL
Direct bilirubin 0.1 mg/dL
Indirect bilirubin 2.7 mg/dL

These results most likely indicate which of the
following?

a. Normal bilirubin metabolism
b. Extrahepatic obstruction
c. Dubin-Johnson syndrome
d. Gilbert’s disease

Answer 37

d. Gilbert’s disease

Dubin-Johnson syndrome and extrahepatic obstruction are conditions that cause elevations in total bilirubin, with the major fraction increased being the conjugated fraction (direct). Gilbert’s disease is a condition resulting from genetic mutation in the gene that produces the enzyme uridyl diphosphate glucuronyl transferase, the enzyme responsible for the conjugation of bilirubin. Therefore Gilbert’s disease will manifest as unconjugated hyperbilirubinemia.

Question 38

(38) Which of the following is measured using glutamate dehydrogenase and is a measure of advanced stages, poor prognosis, and coma in liver disease?

a. Total bilirubin
b. Ammonia
c. Unconjugated bilirubin
d. Urea

Answer 38

b. Ammonia

Severe liver disease is the most common cause of altered ammonia metabolism. Therefore the monitoring of ammonia levels may be used to determine prognosis.

Question 39

(39) In which of the following disease states would you see an elevation in total bilirubin and conjugated bilirubin only?

a. Biliary obstruction
b. Hemolysis
c. Neonatal jaundice
d. Hepatitis

Answer 39

a. Biliary obstruction

Hemolysis and neonatal jaundice would manifest with elevations in total bilirubin primarily as a result of the unconjugated fraction. Biliary obstruction manifests as conjugated hyperbilirubinemia.

Question 40

(40) In which of the following conditions does no activity of glucuronyl transferase result in increased unconjugated bilirubin and kernicterus in neonates and eventual death within 18 months?

a. Gilbert’s disease
b. Dubin-Johnson syndrome
c. Crigler-Najjar syndrome
d. Intravascular hemolysis

Answer 40

c. Crigler-Najjar syndrome

Crigler-Najjar syndrome is an inherited disorder of bilirubin metabolism. Neonates with CriglerNajjar syndrome have no uridyl diphosphate glucuronyl transferase and therefore cannot conjugate bilirubin for excretion. In neonates this increased unconjugated bilirubin will cause kernicterus without aggressive treatment.

Question 41

(41) As a reduction product of bilirubin catabolism, this compound is partially reabsorbed from the intestines through the portal circulation for reexcretion by the liver. What is this compound?

a. Urobilinogen
b. Azobilirubin
c. Biliverdin
d. Urobilin

Answer 41

a. Urobilinogen

When bilirubin becomes conjugated it can enter the intestines. In the gastrointestinal tract, bacteria convert conjugated bilirubin to urobilinogen. Three things will happen to the urobilinogen: (1) it is excreted in the feces; (2) it enters extrahepatic circulation, where it is absorbed and recirculated to the liver and excreted in the feces; and (3) it enters systemic circulation and is excreted in the urine.

Question 42

(42) In the liver, bilirubin is conjugated in the presence of which of the following?

a. b-Glucuronidase
b. Bilirubin oxidase
c. Uridine diphosphate (UDP)–glucuronyl transferase
d. Peroxidase

Answer 42

c. Uridine diphosphate (UDP)–glucuronyl transferase

The enzyme responsible for bilirubin conjugation is uridyl diphosphate glucuronyl transferase.

Question 43

(43) 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

Answer 43

a. Serum AST and ALT levels

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are the most sensitive markers of hepatocellular damage. γ-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.

Question 44

(44) Which of the following conditions is caused by deficient secretion of bilirubin into the bile canaliculi?

a. Gilbert’s disease
b. Physiologic jaundice of the newborn
c. Dubin-Johnson syndrome
d. Hemolytic jaundice

Answer 44

c. Dubin-Johnson syndrome

Dubin-Johnson is an autosomal recessive disorder resulting in a defect in the ability of the liver cell to secrete conjugated bilirubin into the bile.

Question 45

(45) Which of the following enzymes is responsible for the conjugation of bilirubin?

a. Biliverdin reductase
b. Peroxidase
c. UDP–glucuronyl transferase
d. b-Glucuronidase

Answer 45

c. UDP–glucuronyl transferase

UDP-glucuronyl transferase is the enzyme that is responsible for the conjugation of bilirubin.

Question 46

(46) Which of the following analytes is the best indicator of hepatobiliary damage?

a. AST
b. ALT
c. ALP
d. Bilirubin

Answer 46

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are markers of hepatocellular damage, whereas γ-glutamyl transferase (GGT) and alkaline phosphatase (ALP) are markers of hepatobiliary damage.

Question 47

(47) Which of the following fractions of bilirubin in high concentrations is associated with kernicterus in newborns?

a. Delta bilirubin
b. Unconjugated bilirubin
c. Conjugated bilirubin
d. Unconjugated and delta bilirubin

Answer 47

b. Unconjugated bilirubin

Unconjugated bilirubin is insoluble in water and must be transported by albumin to the liver for further metabolism. Albumin binding prevents unconjugated bilirubin from crossing cell membranes and accumulating in cells. Extremely high levels of unconjugated bilirubin can exceed albumin-binding capacity and allow unconjugated bilirubin to cross the immature blood brain barrier in neonates, causing kernicterus (toxic damage to the cells in the basal ganglia).

Question 48

(48) The characteristic laboratory finding in alcoholic cirrhosis includes:

a. Moderate elevations in AST and ALT, normal GGT, and normal ALP
b. Slight elevations in AST and ALT, marked elevations in ALP, normal GGT
c. Slight elevations in AST, ALT, and GGT and marked elevations in 5’ nucleotidase
d. Slight elevations in AST and ALT (AST>ALT), marked elevations in GGT, slight elevations in ALP

Answer 48

d. Slight elevations in AST and ALT (AST>ALT), marked elevations in GGT, slight elevations in ALP

With chronic alcohol abuse, the amount of alanine aminotransferase (ALT) declines, which results in an increased ratio of aspartate aminotransferase (AST) to ALT.
γ-Glutamyltransferase (GGT) is a membrane-bound enzyme that is markedly increased with ethanol use, and alkaline phosphatase (ALP) is slightly elevated with alcohol use.

Question 49

(49) Which of the following liver conditions shows an increase in both conjugated bilirubin and ALP, manifests with antimitochondrial antibodies, and shows a characteristic lipoprotein X on electrophoresis?

a. Hemochromatosis
b. Primary biliary cirrhosis
c. Alcoholic fatty liver
d. Hepatic tumors

Answer 49

b. Primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune disorder that targets the bile ducts. PBC is associated with antimitochondrial antibodies and the presence of lipoprotein X (an abnormal lipoprotein produced in individuals with obstructive biliary tract disease).

Question 50

(50) Which set of results is consistent with uncompensated metabolic acidosis?

a. pH 7.25, HCO3 15 mmol/L, PCO2 37 mm Hg
b. pH 7.30, HCO3 16 mmol/L, PCO2 28 mm Hg
c. pH 7.45, HCO3 22 mmol/L, PCO2 40 mm Hg
d. pH 7.40, HCO3 25 mmol/L, PCO2 40 mm Hg

Answer 50

a. pH 7.25, HCO3 15 mmol/L, PCO2 37 mm Hg

Acidosis will manifest with a pH less than 7.35; because it is metabolic, it would be driven by low levels of bicarbonate (HCO3- <22 mol/L). Because it is an uncompensated condition, the respiratory parameter would be in the normal range (PCO2 35-45 mm Hg).

Question 51

(51) A patient with emphysema who has fluid accumulation in the alveolar sacs (causing decreased ventilation) is likely to be in which of the following acid-base clinical states?

a. Respiratory alkalosis
b. Respiratory acidosis
c. Metabolic acidosis
d. Metabolic alkalosis

Answer 51

b. Respiratory acidosis

A decrease in ventilation would cause the accumulation of the acidic gas PCO2, causing respiratory acidosis.

Question 52

(52) 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

Answer 52

d. Bicarbonate/carbonic acid

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.

Question 53

(53) To maintain electrical neutrality in the red blood cell, bicarbonate leaves the red blood cell and enters the plasma through an exchange mechanism with which of the following?

a. TCO2
b. Sodium
c. Chloride
d. Phosphate

Answer 53

c. Chloride

This process of exchange between bicarbonate and chloride as bicarbonate leaves the red blood cell is termed the chloride shift

Question 54

(54) Increased PCO2 in a patient most commonly results in which of the following primary acid-base abnormalities?

a. Respiratory acidosis
b. Metabolic acidosis
c. Respiratory alkalosis
d. Metabolic alkalosis

Answer 54

a. Respiratory acidosis

PCO2 is an acidic gas controlled by the lungs (respiratory system) and when in increased concentrations will cause respiratory driven acidosis.

Question 55

(55) Which of the following changes will occur with a blood gas sample exposed to room air?

a. pH increased
b. pCOO2 increased
c. pO2 decreased
d. Ionized calcium increased

Answer 55

a. pH 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.

Question 56

(56) Which of the following is the correct collection and handling for the analysis of blood gases?

a. Plastic syringe, dry heparin, store on ice, assay within 1 hour
b. Glass syringe, liquid heparin, store on ice, assay within 15 minutes
c. Glass syringe, no additive, store on ice, assay within 15 minutes
d. Plastic syringe, dry heparin, store at room temperature, assay within 15 minutes

Answer 56

d. Plastic syringe, dry heparin, store at room temperature, assay within 15 minutes

Ideal blood gas collection should include collection in a plastic syringe containing dry heparin; it should be collected, delivered to the laboratory, and assayed within 15 minutes at room temperature. If the process will exceed 15 minutes, samples are stable for 45 minutes stored on crushed ice.

Question 57

(57) What is the blood pH when the partial pressure of carbon dioxide (pCO2) is 45 mm Hg and the bicarbonate is 28 mmol/L?

a. 7.00
b. 7.11
c. 7.33
d. 7.41

Answer 57

d. 7.41

The pH may be calculated using the Henderson-Hasselbalch equation for the bicarbonate–carbonic acid buffer system as follows (NOTE: In plasma and at body temperature [37°C] the pKa of the bicarbonate buffering system is 6.1):

pH = pKa + log (HCO3- / (0.03) (PCO2)
pH = 6.1 + log28 / (0:03) (45)
pH = 6.1 + log20.7
pH = 7.42

Question 58

(58) What is the normal ratio of bicarbonate to dissolved carbon dioxide in arterial blood?

a. 1:10
b. 10:1
c. 20:1
d. 1:20

Answer 58

c. 20:1

In healthy individuals when the kidneys and lungs are functioning at full capacity the ratio of bicarbonate to carbonic acid is 20:1.

Question 59

(59) Which of the following sets of blood gas data is considered normal?

a. pH 7.33, HCO3 18 mmol/L, pCO2 32 mm Hg
b. pH 7.30, HCO3 16 mmol/L, pCO2 28 mm Hg
c. pH 7.45, HCO3 22 mmol/L, pCO2 40 mm Hg
d. pH 7.40, HCO3 25 mmol/L, pCO2 40 mm Hg

Answer 59

d. pH 7.40, HCO3 25 mmol/L, pCO2 40 mm Hg

Reference intervals for arterial blood gases are as follows:
pH = 7.35-7.45
PCO2 = 35-45 mm Hg
PO2 = 80-110 mmol/L
HCO3- =22-26 mmol/L

Question 60

(60) Which of the following values would be seen in uncompensated metabolic acidosis?

a. pH 7.38
b. pCO2 52 mm Hg
c. HCO3- 15 mmol/L
d. pH 7.53

Answer 60

c. HCO3- 15 mmol/L

In uncompensated metabolic acidosis the pH would be decreased (<7.35), and this decrease would be driven by the metabolic component (HCO3-). HCO3- would be decreased (<22 mmol/L). Because it is uncompensated, the respiratory component (PCO2) would be normal (34-45 mmol/L).

Question 61

(61) Which of the following blood gas disorders is most commonly associated with an abnormal anion gap?

a. Metabolic acidosis
b. Metabolic alkalosis
c. Respiratory acidosis
d. Respiratory alkalosis

Answer 61

a. Metabolic acidosis

The anion gap, especially when elevated, is useful in diagnosing the type of metabolic acidosis and in indicating if a mixed disorder exists.

Question 62

(62) Which of the following statements best describes the predominant feedback system associated with endocrinology?

a. Decreased levels of circulating hormones directly result in the production of hormone from the target organ
b. Increased circulating levels of hormones directly result in the production of releasing factor from the hypothalamus
c. Increased circulating levels of hormones directly result in the production of inhibiting factor from the hypothalamus
d. Normal levels of circulating hormones directly result in the production of hormone from the target organ

Answer 62

c. Increased circulating levels of hormones directly result in the production of inhibiting factor from the hypothalamus

The predominant feedback system associated with the endocrine system is negative feedback, in which increased levels of hormones feed back negatively to the hypothalamus and pituitary.

Question 63

(63) The following laboratory results are from a 54-yearold woman complaining of weight gain, intolerance to heat, fatigue, and not being able to stay awake.

Na = 140 mmol/L
K = 4.0 mmol/L
Glucose = 75 mg/dL
Aldosterone = 8 ng/dL
Ionized Ca = 4.8 mg/dL
Mg = 2.0 mEq/L
Phos = 3.0 mg/dL
TSH = 7.2 µU/mL
FT4 = 1.0 ng/dL
Cortisol = 10 µg/dL

Which of the following conditions best fits with the
history and data?

a. Hyperthyroidism
b. Cushing’s syndrome
c. Hyperaldosteronism
d. Hypothyroidism

Answer 63

d. Hypothyroidism

All results are normal except for the result for thyroid-stimulating hormone (TSH), which is increased. Because TSH is produced at the pituitary, increased TSH results indicate a hypothyroid condition.

Question 64

(64) A 42-year-old woman presents to her physician with truncal obesity, bruising, hypertension, hyperglycemia, and increased facial hair. The physician suspects an endocrine disturbance. Significant test results are as follows:

TSH = 3.0 µU/mL
FT4 = 1.0 ng/dL
Glucose = 90 mg/dL
Serum cortisol (8 AM) = 45 µg/dL
Plasma ACTH (8 AM) = 152 pg/mL
Urine free cortisol = Increased

Dexamethasone suppression tests
Overnight 300 nmol/L
High dose >50% suppression

What is the most probable condition?
a. Pituitary tumor
b. Addison’s disease
c. Adrenal adenoma
d. Ectopic ACTH production

Answer 64

a. Pituitary tumor

The three main noniatrogenic causes of Cushing’s syndrome (hypercortisolism) include (1) a pituitary tumor (Cushing’s disease), (2) an adrenal adenoma (Cushing’s syndrome), and (3) ectopic adrenocorticotropic hormone (ACTH) production. Pituitary-driven Cushing’s disease is ACTH dependent and results from a benign pituitary adenoma that produces ACTH. Therefore ACTH values are increased. During bilateral inferior petrosal sinus sampling the gradient between the inferior petrosal sinus and peripheral venous site after corticotropin-releasing hormone administration in Cushing’s disease is greater than 3 (often close to 50).

Question 65

(65) Hypothyroidism is best characterized by which of the following sets of test results?

a. TSH 0.2 µU/mL, FT3 8.9 pg/mL, FT4 4.5 ng/dL
b. TSH 8.5 µU/mL, FT3 1.0 pg/mL, FT4 0.5 ng/dL
c. TSH 0.1 µU/mL, FT3 1.1 pg/mL, FT4 0.8 ng/dL
d. TSH 3.9 µU/mL, FT3 3.0 pg/mL, FT4 1.0 ng/dL

Answer 65

b. TSH 8.5 µU/mL, FT3 1.0 pg/mL, FT4 0.5 ng/dL

Hypothyroidism is a condition in which thyroid hormone levels are low; therefore because of positive feedback the thyroid stimulating hormone will be increased.

Question 66

(66) The release of thyroid-releasing hormone (TRH) would result in which of the following actions from the HPT axis?

a. Decreased release of thyroid-stimulating hormone from the pituitary gland
b. Increased release of thyroid-stimulating hormone from the thyroid gland
c. Increased release of thyroid hormones from the thyroid glands
d. Increased release of thyroid hormones from the pituitary gland

Answer 66

c. Increased release of thyroid hormones from the thyroid glands

Thyroid-releasing hormone (TRH) is a tripeptide produced from the hypothalamus. TRH acts directly on the pituitary gland to produce TSH, which acts on the thyroid gland to produce T3 and T4.

Question 67

(67) A serum thyroid panel reveals an increase in total T4, normal TSH, and a normal fT4. What is the most likely cause of these results?

a. Increased thyroxine-binding protein
b. Secondary hyperthyroidism
c. Subclinical hypothyroidism
d. Subclinical hyperthyroidism

Answer 67

a. Increased thyroxine-binding protein

Thyroid-stimulating hormone (TSH) is the most sensitive indicator of thyroid dysfunction. When TSH levels are normal is it unlikely that a thyroid abnormality exists. The only abnormal result provided is the total T4 levels, which inherently are subject to false elevations in individuals with abnormal binding proteins. This is why total levels of thyroid hormones (TT3 and TT4) are not routinely obtained in clinical practice.

Question 68

(68) Thyroid hormones are derived from which of the following?

a. Histidine
b. Cholesterol
c. Tyrosine
d. Phenylalanine

Answer 68

c. Tyrosine

Two essential components needed for thyroid hormone production include tyrosine and iodine.

Question 69

(69) In patients with developing subclinical hyperthyroidism, TSH levels will likely be ______, and fT4 will likely be ______.

a. Decreased, increased
b. Increased, decreased
c. Decreased, normal
d. Increased, normal

Answer 69

c. Decreased, normal

The term subclinical refers to a condition that can be detected using sensitive laboratory tests, but has not progressed to the point of producing symptoms or abnormal thyroid hormone levels. In subclinical hypothyroidism, the thyroid stimulating hormone will be decreased but the thyroid hormone levels will still be normal.

Question 70

(70) A 30-year-old woman is admitted to the hospital. She has truncal obesity, buffalo humpback, moon face, purple striae, hypertension, hyperglycemia, increased facial hair and amenorrhea. The physician orders endocrine testing. The results are as follows:

Urine free cortisol = Increased
Serum cortisol (8 AM) = Increased
Plasma ACTH = Decreased

Dexamethasone suppression test
Overnight: No suppression
High dose: No suppression

What is the most probable condition?

a. Addison’s disease
b. Cushing’s disease
c. Conn’s syndrome
d. Cushing’s syndrome

Answer 70

d. Cushing’s syndrome

The three main noniatrogenic causes of Cushing’s syndrome (hypercortisolism) include (1) a pituitary tumor (Cushing’s disease), (2) an adrenal adenoma (Cushing’s syndrome), and (3) ectopic adrenocorticotropic hormone (ACTH) production. Cushing’s syndrome driven by an adrenal adenoma is ACTH independent, resulting in an adrenal adenoma producing cortisol. Because the pituitary gland is functional, it is still responsive to negative feedback to the pituitary because of the increased cortisol levels and the ACTH result will be decreased. During a bilateral inferior petrosal sinus sampling the gradient between the inferior petrosal sinus and peripheral venous site after corticotropin-releasing hormone administration in Cushing’s syndrome is less than 2.

Question 71

(71) Trophic hormones are produced by the ______, and releasing factors are produced by the ______.

a. Hypothalamus; pituitary
b. Pituitary; hypothalamus
c. Specific endocrine glands; hypothalamus
d. Pituitary; target gland

Answer 71

b. Pituitary; hypothalamus

Releasing and inhibiting factors are produced from the hypothalamus, and trophic hormones are produced from the pituitary.

Question 72

(72) When free thyroxine cannot be measured directly, the free thyroxine index (FT4I) may be calculated by using which measured laboratory data?

a. TSH and T3 resin uptake
b. T4 and T3 resin uptake
c. TSH and T4
d. T3 and T3 resin uptake

Answer 72

b. T4 and T3 resin uptake

The free thyroxine (FT4) index is calculated as follows:
FT4I = TT4 x Thyroid hormone binding ratio/100

Question 73

(73) The most commonly used challenge test to assist in evaluating a potential growth hormone deficiency is the:

a. Insulin challenge test
b. Dexamethasone suppression test
c. Oral glucose tolerance test
d. Captopril suppression test

Answer 73

a. Insulin challenge test

Assuming that a screening test is abnormal, a definitive stimulation test is often performed. The definitive test involves looking at the growth hormone response after intravenous insulin infusion.

Question 74

(74) Symptoms of primary adrenal insufficiency (Addison’s disease) include which of the following?

a. Hypercortisolism
b. Hypokalemia
c. Hypertension
d. Acidosis

Answer 74

b. Hypokalemia

Pheochromocytoma is a rare and usually benign tumor arising from the adrenal gland that results in the increased production of catecholamines (epinephrine and norepinephrine). Total catecholamine levels are not recommended for diagnosis because catecholamines are highly labile and increase as a result of stress and pain. Therefore the recommendation is to assay plasma free metanephrines (metanephrines and normetanephrines), which are the metabolites of epinephrine and norepinephrine.

[explanation from Elsevier unclear]

Question 75

(75) A TRH stimulation test is performed, and a flat response is received from this test procedure. This most likely indicates:

a. Secondary hypothyroidism
b. Tertiary hypothyroidism
c. Primary hypothyroidism
d. Secondary hyperthyroidism

Answer 75

a. Secondary hypothyroidism

Thyrotropin-releasing hormone (TRH) is a tripeptide produced from the hypothalamus that acts on the pituitary to produce thyroid-stimulating hormone (TSH). When exogenous TRH is administered to a person and there is no response, it is indicative of a nonfunctioning pituitary gland. Thyroid gland disorders arising from a problem with the pituitary gland are referred to as secondary conditions.

Question 76

(76) The first step in the synthesis of thyroid hormones is:

a. Iodide trapping
b. Binding of thyroglobulin
c. Oxidation of iodine
d. Oxidation of TG molecule

Answer 76

a. Iodide trapping

Thyroid hormone production occurs in five steps: (1) iodide trapping, (2) organification, (3) coupling, (4) storage, and (5) secretion.

Question 77

(77) Which of the following conditions is a result of catecholamine excess, includes two classifications (MEN 1 and MEN 2), and may result in death from severe cardiovascular complications?

a. Cushing’s syndrome
b. Conn’s syndrome
c. Addison’s disease
d. Pheochromocytoma

Answer 77

d. Pheochromocytoma

Pheochromocytoma results in the excess production of catecholamines, which increase cardiac output and blood pressure to divert blood to muscle or brain, mobilize fuel from storage, and cause hypertension. If pheochromocytoma is untreated, death may occur from cardiovascular complications.

Question 78

(78) The main estrogen produced by the ovaries and used to evaluate ovarian function is:

a. Estriol
b. Estradiol
c. Epiestriol
d. Estrogen

Answer 78

b. Estradiol

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.

Question 79

(79) The Michaelis-Menten theory states which of the following?

a. E + S + I → ES +EI + ESI → E+P
b. E + S ⇿ ES → E+P
c. E + S + I → ES +EI → E+P
d. E ⇿ ES → E+P

Answer 79

b. E + S ⇿ ES → E+P

The general relationship among an enzyme, its substrate, and its product is represented using the Michaelis-Menten theory, which is represented as E + S ⇿ ES → E + P, where E is the enzyme, S is the substrate, ES is the enzyme substrate complex, and P is the product.

Question 80

(80) Which of the following enzymes is the best indicator of pancreatic function?

a. AST
b. ALT
c. GGT
d. Lipase

Answer 80

d. Lipase

Lipase and amylase are both markers of pancreatic function; however, lipase is considered more specific because it remains elevated longer in acute pancreatitis.

Question 81

(81) Which of the following enzymes catalyzes the conversion of p-nitrophenyl phosphate to a colored pnitrophenol product?

a. AST
b. ALT
c. ALP
d. GGT

Answer 81

c. ALP

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.

Question 82

(82) One international unit of enzyme activity is the amount of enzyme that under specified reaction conditions of substrate concentration, pH, and temperature, causes usage of substrate at the rate of:

a. 1 millimole/min
b. 1 micromole/min
c. 1 nanomole/min
d. 1 picomole/min

Answer 82

b. 1 micromole/min

One international unit of enzyme activity is the amount of enzyme that uses substrate at the rate of 1 μmole/min.

Question 83

(83) 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°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

Answer 83

d. Reject the sample because the citrate will interfere

The recommended sample of choice for analysis of creatinine kinase (CK) is serum or heparin plasma. Anticoagulants other than heparin may inhibit CK activity.

Question 84

(84) 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

Answer 84

c. Highest levels are seen in Duchenne’s muscular dystrophy

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.

Question 85

(85) Which of the following conditions can “physiologically” elevate serum alkaline phosphatase?

a. Hyperparathyroidism
b. Diabetes
c. Third-trimester pregnancy
d. Nephrotic syndrome

Answer 85

c. Third-trimester pregnancy

Elevated alkaline phosphatase (ALP) levels may be seen with bone and liver disorders. In addition, ALP will also be increased physiologically during periods of bone growth, when bone fractures are healing, and in pregnancy.

Question 86

(86) 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

Answer 86

a. Linear phase

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.

Question 87

(87) 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

Answer 87

a. Red top

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.

Question 88

(88) Which of the following enzymes catalyzes the conversion of starch to glucose and maltose?

a. Lipase
b. Amylase
c. ALT
d. GGT

Answer 88

b. Amylase

Amylase is an enzyme that can degrade complex carbohydrate molecules such as starch.

Question 89

(89) Hyperparathyroidism is most consistently associated with which of the following?

a. Hypocalcemia
b. Hypercalciuria
c. Hypophosphatemia
d. Metabolic alkalosis

Answer 89

c. Hypophosphatemia

Parathyroid hormone (PTH) is responsible for maintaining calcium levels by acting on bone and the kidneys and by activating vitamin D. PTH acts on the bone to release calcium and phosphorus through osteoclastic activity. Once released from bone, PTH acts on the kidneys to allow absorption of calcium and excretion of phosphorous. High levels of PTH would most likely manifest with hypercalcemia and hypophosphatemia.

Question 90

(90) What percentage of serum calcium is in the ionized form?

a. 30%
b. 50%
c. 60%
d. 80%

Answer 90

b. 50%

Calcium exists in three forms, 45% unbound (ionized), 45% bound to albumin, and 10% bound to other anions. Only the ionized (unbound form) is the physiologically active form.

Question 91

(91) Which of the following best describes the action of parathyroid hormone?

a. PTH increases calcium and phosphorus reabsorption in the kidney
b. PTH decreases calcium and phosphorus release from bone
c. PTH decreases calcium and increases phosphorus reabsorption in the liver
d. PTH increases calcium reabsorption and decreases phosphorus reabsorption in the kidney

Answer 91

d. PTH increases calcium reabsorption and decreases phosphorus reabsorption in the kidney

Parathyroid hormone (PTH) is responsible for maintaining calcium levels by acting on bone and the kidneys and by activating vitamin D. PTH acts on the bone to release calcium and phosphorus through osteoclastic activity. Once released from bone, PTH acts on the kidneys to cause the kidneys to absorb calcium and excrete the phosphorous.

Question 92

(92) Which of the following is most likely to produce an elevated plasma potassium result?

a. Hypoparathyroidism
b. Cushing’s syndrome
c. Diarrhea
d. Hemolysis

Answer 92

d. Hemolysis

Hemolysis is the most common cause of hypercalcemia.

[[NOTE: I think it should be “Hemolysis is the most common cause of HYPERKALEMIA” since the question was pertaining to potassium levels]]

Question 93

(93) Which of the following hormones involved in calcium regulation acts by decreasing both calcium and phosphorous?

a. PTH
b. Calcitonin
c. Vitamin D
d. Cortisol

Answer 93

b. Calcitonin

Calcitonin is a hormone produced by the C cells of the thyroid. Calcitonin is involved in calcium regulation and inhibits bone breakdown; thus it decreases calcium and phosphorus.

Question 94

(94) Which of the following electrolytes is the chief plasma cation whose main function is maintaining osmotic pressure?

a. Chloride
b. Potassium
c. Sodium
d. Bicarbonate

Answer 94

c. Sodium

Sodium is the predominant plasma cation and maintains osmotic pressure.

Question 95

(95) Which of the following conditions is associated with hypernatremia?

a. Diabetes insipidus
b. Hypoaldosteronism
c. Diarrhea
d. Acidemia

Answer 95

a. Diabetes insipidus

Diabetes insipidus is a condition resulting from a deficiency in antidiuretic hormone that manifests with excessive thirst and excretion of large amounts of severely diluted urine. Because the body cannot conserve water, sodium levels rise and dehydration may occur.

Question 96

(96) Which of the following conditions will elevate ionized calcium?

a. Diabetes mellitus
b. Hyperlipidemia
c. Acidosis
d. Alkalosis

Answer 96

c. Acidosis

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.

Question 97

(97) The anion gap is useful (among other things) as an inexpensive measure of quality control for which of the following analytes?

a. Blood gas analyses
b. Sodium, potassium, chloride, and total carbon dioxide
c. Calcium, phosphorus, and magnesium
d. AST, ALT, GGT, and ALP

Answer 97

b. Sodium, potassium, chloride, and total carbon dioxide

The anion gap is often reported with electrolyte measurements as a means of identifying shifts that may occur in these assays. Because the anion gap is a calculation parameter, it is an inexpensive and easy quality control check.

Question 98

(98) Pseudohyperkalemia is most commonly a result of which of the following?

a. Metabolic acidosis
b. Hemolysis
c. Hyperaldosteronism
d. Hyperparathyroidism

Answer 98

b. Hemolysis

Hemolysis can often result from a tourniquet being on the arm too long.

Question 99

(99) The following results were seen on a blood sample:

Na+ = 140 mEq/L
Cl- = 105 mEq/L
K+ = 15.0 mEq/L
HCO3 = 22 mmol/L

The technologist should do which of the following?

a. Report the results
b. Repeat and check the chloride result
c. Repeat and check the Na+ result
d. Check the sample for hemolysis

Answer 99

d. Check the sample for hemolysis

A potassium value of 15 mEq/L is too high to be considered physiologic. The sample should be checked for a potential preanalytical interference, including hemolysis and incorrect collection tube (contamination via an anticoagulant).

Question 100

(100) The major intracellular cation is which of the following?

a. Potassium
b. Sodium
c. Chloride
d. Bicarbonate

Answer 100

a. Potassium

The major intracellular cation is potassium. Sodium is the major extracellular cation.