Heme Derivatives (Chemistry)

Question 1

Hemoglobin A1C represents:

A) valine substitution for glutamine at the 6th position of the beta chain of hemoglobin
B) ketone formation due to hydrolysis of the alpha and beta C-terminus forming an abnormal hemoglobin
C) glycosylation of valine in the polypeptide N-terminus of normal adult hemoglobin
D) glucose reduction in the presence of oxygen at the N-terminus of the polupeptide chains of hemoglobin

Answer 1

C) glycosylation of valine in the polypeptide N-terminus of normal adult hemoglobin

Question 2

The principle of the occult blood test depends upon the:

A) coagulase ability of blood
B) oxidative power of atmospheric oxygen
C) hydrogen peroxide in hemoglobin
D) peroxidase-like activity of hemoglobin

Answer 2

D) peroxidase-like activity of hemoglobin

Question 3

A breakdown product of hemoglobin is:

A) lipoprotein
B) bilirubin
C) hematoxylin
D) Bence Jones protein

Answer 3

B) bilirubin

Question 4

Hemoglobin S can be separated from hemoglobin D by:

A) electrophoresis on a different medium and acidic pH
B) hemoglobin A2 quantitation
C) electrophoresis at higher voltage
D) Kleihavuer-Betke acid elution

Answer 4

A) electrophoresis on a different

Question 5

On electrophoresis at alkaline pH, which of the following is the slowest migrating hemoglobin?

A) HgbA
B) HgbS
C) HgbC
D) HgbF

Answer 5

C) HgbC

Question 6

The hemoglobin that is resistant to alkali (KOH) denaturation is:

A) A
B) A2
C) C
D) F

Answer 6

D) F

Question 7

The following bilirubin results are obtained on a patient:

Day 1: 4.3 mg/dL (73.5 umol/L)
Day 2: 4.6 mg/dL (78.7 umol/L)
Day 3: 4.5 mg/dL (77.0 umol/L)
Day 4: 2.2 mg/dL (37.6 umol/L)
Day 5: 4.4 mg/dL (75.2 umol/L)
Day 6: 4.5 mg/dL (77.0 umol/L)

Given that the controls were within range each day, what is a probable explanatino for the result on day 4?

A) no explanation necessary
B) serum, not plasma, was used for testing
C) specimen had prolonged exposure to light
D) specimen was hemolyzed

Answer 7

C) specimen had prolonged exposure to light

Question 8

Urobilinogen is formed in the:

A) kidney
B) spleen
C) liver
D) intestine

Answer 8

D) intestine

Question 9

In bilirubin determinations, the purpose of adding a concentrated caffeine solution or methyl alcohol is to:

A) allow indirect bilirubin to react with color reagent
B) dissolve conjugated bilirubin
C) precipitate protein
D) prevent any change in pH

Answer 9

A) allow indirect bilirubin to react with color reagent

Question 10

If the total bilirubin is 3.1 mg/dL (53.0 umol/L) and the conjugated bilirubin is 2.0 mg/dL (34.2 umol/L), the unconjugated bilirubin is:

A) 0.5 mg/dL (8.6 umol/L)
B) 1.1 mg/dL (18.8 umol/L)
C) 2.2 mg/dL (37.6 umol/L)
D) 5.1 mg/dL (87.2 umol/L)

Answer 10

B) 1.1 mg/dL (18.8 umol/L)

Question 11

The principle of the tablet test for bilirubin in urine or feces is:

A) the reaction between bile and 2,4-dichloronitrobenzene to a yellow color
B) the liberation of oxygen by bile to oxidize orthotolidine to a blue-purple color
C) chemical coupling of bile with a diazonium slat to form a brown color
D) chemical coupling of bilirubin with a diazonium salt to form a purple color

Answer 11

D) chemical coupling of bilirubin with a diazonium salt to form a purple color

Question 12

Ten heparinized plasma samples samples were assayed for bilirubin by Jendrassik-Grof method on analyzer 2, in a method comparison study. The results were all 10-20% higher from analyzer 2 most likely because:

A) the caffine-benzoate stabilizer in the 2nd analyzer prevented falsely decreased results as found in analyzer 1
B) fibrinogen in the plasma samples caused falsely decreased results in the Jendrassik-Grof method
C) alcohol reagents in the second method cause precipitation of proteins and increased background turbidity
D) hemolysis caused greater interference in method 1 than in method 2

Answer 12

C) alcohol reagents in the second method cause precipitation of proteins and increased background turbidity

Question 13

Serial bilirubin determinations performed by Jendrassik-Grof method are charted below:

Day 1:
Time: 7 am
Assayed: 8 am
Result: 14.0 mg/dL (239.4 umol/L)

Day 2:
Time: 7 am
Assayed: 6 pm
Result: 9.0 mg/dL (153.9 umol/L)

Day 3:
Time: 6 am
Assayed: 8 pm
Result: 15.0 mg/dL (256.5 umol/L)

The best explanation for the results is:

A) sample on day 2 has mild hemolysis and hemoglobin deterioration
B) sample on day 2 has exposure to light
C) sample on day 2 shows normal day to day variation
D) reagent deterioration is evident on day 3

Answer 13

B) sample on day 2 has exposure to light

Question 14

In the liver, bilirubin is concerted to:

A) urobilinogen
B) urobilin
C) bilirubin-albumin complex
D) bilirubin diglucuronide

Answer 14

D) bilirubin diglucuronide

Question 15

In which of the following disease states is conjugated bilirubin a major serum component?

A) biliary obstruction
B) hemolysis
C) neonatal jaundice
D) erythroblastosis fetalis

Answer 15

A) biliary obstruction

Question 16

Kernicterus is an abnormal accumulation of bilirubin in:

A) heart tissue
B) brain tissue
C) liver tissue
D) kidney tissue

Answer 16

B) brain tissue

Question 17

In which of the following conditions does decreased activity of glucuronyl transferase result in increased unconjugated bilirubin and kernicterus in neonates?

A) Gilbert disease
B) Rotor disease
C) Dubin-Johnson syndrome
D) Crigler-Najjar syndrome

Answer 17

D) Crigler-Najjar syndrome

Question 18

A 21 year old with nausea, vomiting, and jaundice has the following laboratory findings:

total serum bilirubin
Patient Value: 8.5 mg/dL (145.4 umol/L)
Reference Range: 0-1.0 mg/dL (0.0-17.1 umol/L)

conjugated serum bilirubin
Patient Value: 6.1 mg/dL (104.3 umg/dL)
Reference Range: 0-0.5 mg/dL (0.0-8.6 umol/L)

urine urobilinogen: increased
fecal urobilinogen: decreased
urine bilirubin: positive

AST
Patient Value: 300 U/L
Reference Range: 0-50 U/L

alkaline phosphatase
Patient Value: 170 U/L
Reference Range: 0-150 U/L

These can best be explained as representing:

A) unconjugated hyperbilirubinemia, probably due to hemolysis
B) unconjugated hyperbilirubinemia, probably due to toxic liver damage
C) conjugated hyperbilirubiemia, probably due to hepatocellular disease
D) conjugated hyperbilirubinemia, probably due to hepatocellular obstruction

Answer 18

C) conjugated hyperbilirubiemia, probably due to hepatocellular disease

Question 19

A stool specimen that appears black and tarlike should be tested for the presence of:

A) occult blood
B) fecal fat
C) trypsin
D) excess mucus

Answer 19

A) occult blood

Question 20

What substance gives feces its normal color?

A) uroerythrin
B) urochrome
C) urobilin
D) urobilinogen

Answer 20

C) urobilin

Question 21

A condition in whihc erythrocute protoporhyrin is increased is:

A) acute intermittent prophyria
B) iron deficiency anemia
C) porphyria cutanea tarda
D) acute porphyric attack

Answer 21

B) iron deficiency anemia

Question 22

The definitive diagnosis for hereditary coproporphyria (HPC) is a markedly increased:

A) urine delta-aminolevulinic acid (ALA)
B) urine prophobilinogen (PBG)
C) fecal coproporphurin III
D) erythrocyte protoprophyrin

Answer 22

C) fecal coproporphurin III

Question 23

A fresh urine sample is received for analysis for “porphyrins” or “porphuria” without further information or speifications. Initial analysis should include:

A) porphyrin screen and quantitative total porphyrin
B) quantitative total porphyrin and porphobilinogen screen
C) porphyrin and porphobilinogen screen
D) porphobilinogen screen and ion-exchange analysis for porphobilinogen

Answer 23

C) porphyrin and porphobilinogen screen

Question 24

Which of the following enzymes of heme biosynthesis is inhibited by lead?

A) aminolevulinate synthase
B) porphobilinogen synthase
C) uroporphyrinogen synthase
D) bilirubin synthetase

Answer 24

B) porphobilinogen synthase

Question 25

In amniotic fluid, the procedure used to detect hemolytic disease of the newborn is:

A) measurement of absorbance at 450 nm
B) creatinine
C) lecithin/sphigomyelin
D) estriol

Answer 25

A) measurement of absorbance at 450 nm

Question 26

Hemoglobin S can be separated from hemoglobin D by which of the following methods?

A) citrate agar gel electrophoresis at pH 5.9
B) thin-layer chromatography
C) alkali denaturation
D) agarose gel electrophoresis at pH 8.4

Answer 26

A) citrate agar gel electrophoresis at pH 5.9

Question 27

Before unconjugated bilirubin can react with Ehrlich diazo reagent, which of the following must be added?

A) acetone
B) ether
C) distilled water
D) caffeine

Answer 27

D) caffeine

Question 28

The most widely used mehtods for bilirubin measurements are those based on the:

A) Jaffe reaction
B) Schales and Schales method
C) 8-hydroxyquinoline reaction
D) Jendrassik-Grof method

Answer 28

D) Jendrassik-Grof method

Question 29

In the Malloy and Evelyn method for the determination of bilirubin, the reagent that is reacted with bilirubin to form a purple azobilirubin is:

A) dilute sulfuric acid
B) diazonium sulfate
C) sulfobromphthalein
D) diazotized sulfanilic acid

Answer 29

D) diazotized sulfanilic acid

Question 30

In the Jendrassik-Grof method for the determination of serum bilirubin, concentration, quantitation is obtained by measuring the green color of:

A) azobilirubin
B) bilirubin glucuronide
C) urobilin
D) urobilinogen

Answer 30

A) azobilirubin

Question 31

In the Jendrassik-Grof reaction for total bilirubin, alkaline tartrate is added to:

A) form diazo bilirubin, a reddish chromogen
B) eliminate many spectrophotometric interferences
C) act as an accelerator
D) react with delta-bilirubin

Answer 31

B) eliminate many spectrophotometric interferences

Question 32

In amniotic fluid, the procedure used to detect Rh isosensitization is:

A) human amniotic placental lactogen (HPL)
B) alpha-fetoprotein
C) measurement of absorbance at 450 nm
D) creatinine

Answer 32

C) measurement of absorbance at 450 nm