Quiz 9: Porphyrias and Hemoglobin

Question 1

The porphyrias can be classified according to disease symptoms as:

(a) Acquired at birth or acquired later in life
(b) Erythropoietic or hepatic
(c) Hematologic or muscular
(d) Neurologic or cutaneous

Answer 1

(b) Erythropoietic or hepatic

Question 2

Elevated urinary prophobilinogen (PBG) concentration with negative fecal porphyrin results indicates:

(a) Acute intermittent porphyria (AIP)
(b) Erythropoietic protoporphyria (EPP)
(c) Hereditary coproporphyria (HCP)
(d) Porphyria cutanea tarda (PCT)

Answer 2

(a) Acute intermittent porphyria (AIP)

Question 3

Porphyria cutanea tarda (PCT) is identified by:

(a) Chromatographic analysis of a 24-hour urine collection
(b) Scanning fluorescence of plasma
(c) Screening for PBG in a random urine specimen
(d) Separation of fecal porphyrins in a 24-hour specimen

Answer 3

(a) Chromatographic analysis of a 24-hour urine collection

Question 4

Suspected erythropoietic protoporphyria (EPP) is elevated by:

(a) Assessing plasma or whole blood for protoporphyrin
(b) Enzymatic measurement of hydroxymethylbilane synthase
(c) HPLC analysis of a urine specimen
(d) Molecular testing for ferrochelatase

Answer 4

(a) Assessing plasma or whole blood for protoporphyrin

Question 5

Porphobilinogen traditionally was measured in the urine using:

(a) Chromatography
(b) Electrophoresis
(c) Spectrophotometry
(d) The Watson-Schwartz method

Answer 5

(d) The Watson-Schwartz method

Question 6

Specimens collected for evaluation of porphyria should be:

(a) Allowed to clot at room temperature for an hour
(b) Diluted to less than 25 mg/dL creatinine
(c) Exposed to light and air to oxidize the analytes
(d) Protected from light and stored cold

Answer 6

(d) Protected from light and stored cold

Question 7

Inherited disorders in which a genetic defect causes abnormalities in rate and quantity of synthesis of structurally normal polypeptide chains/globin chains of the hemoglobin molecules are called:

(a) Hemoglobinopathies
(b) Molecular dyscrasias
(c) Porphyrias
(d) Thalassemias

Answer 7

(d) Thalassemias

Question 8

Molecular diagnostic techniques that can help diagnose hemoglobin disorders such as hemoglobinopathies and thalassemias include:

(a) Chemical separation, identification, and quantification of mixture components
(b) Separation of macromolecules and their fragments, based on their size and charge
(c) Reverse oligonucleotide probe hybridization, next generation sequencing
(d) The use of specific monoclonal antibodies

Answer 8

(c) Reverse oligonucleotide probe hybridization, next generation sequencing

Question 9

Which type of alpha-thalassemia results from deletion of three genes and produces a moderate hemolytic anemia?

(a) Hemoglobin Bart’s
(b) Hemoglobin H disease
(c) Hydrops fetalis
(d) Thalassemia trait

Answer 9

(b) Hemoglobin H disease

Question 10

The most effective way to quantitate hemoglobin A2 is by:

(a) Alkali denaturation test
(b) Citrate agar electrophoresis
(c) Column chromatography
(d) Densitometry

Answer 10

(c) Column chromatography

Question 11

Serum or plasma myoglobin concentrations are used as:

(a) An early marker of acute myocardial infarction
(b) An indicator of congestive heart failure
(c) Lead poisoning indicator
(d) Liver function tests

Answer 11

(a) An early marker of acute myocardial infarction

Question 12

Which of the following is the best test to differentiate beta-thalassemia minor from iron deficiency anemia?

(a) Complete blood count
(b) Hemoglobin A2 quantitation
(c) Hemoglobin electrophoresis (cellulose acetate, alkaline pH)
(d) Solubility test

Answer 12

(b) Hemoglobin A2 quantitation

Question 13

Which is the correct sequence of electrophoretic migration of hemoglobins from slowest to fastest on cellulose acetate at an alkaline pH?

(a) A, F, S, C
(b) C, A, S, F
(c) C, S, A, F
(d) C, S, F, A

Answer 13

(d) C, S, F, A

Question 14

What compound chelates iron and is the immediate precursor of heme formation?

(a) Porphobilinogen
(b) Protoporphyrinogen IX
(c) Uroporphyrinogen III
(d) Protoporphyrin IX

Answer 14

(d) Protoporphyrin IX

Question 15

A patient has an abnormal hemoglobin band that migrates with Hb S on cellulose acetate (pH 8.4) hemoglobin electrophoresis. The solubility test is negative. Which test should be performed next?

(a) Citrate agar (pH 6.2) electrophoresis
(b) Hb A2 quantitation
(c) Acid elution stain
(d) Blood film evaluation

Answer 15

(a) Citrate agar (pH 6.2) electrophoresis

Question 16

Silent carriers of alpha-thalassemia are missing how many alpha genes?

(a) 1
(b) 2
(c) 3
(d) 4

Answer 16

(a) 1

Question 17

Which hemoglobin contains four gamma chains and has an extremely high affinity for oxygen?

(a) Hb Bart’s
(b) Hb F
(c) Hb Gower I
(d) Hb Portland I

Answer 17

(a) Hb Bart’s

Question 18

A patient with Southeast Asian heritage is found to have a mild microcytic anemia and a few target cells. Hemoglobin electrophoresis on cellulose acetate at pH 8.4 reveals a major band that migrates with HbA2 and no Hb A. On citrate agar electrophoresis, the band travels in the position of Hb A. What is the most probable abnormal hemoglobin present?

(a) Hb A
(b) Hb C
(c) Hb D
(d) Hb E

Answer 18

(d) Hb E

Question 19

Detection of carriers of hereditary coproporphyria should include analysis of:

(a) 24-hour urine for porphobilinogen
(b) Fresh morning urine for delta-aminolevulinic acid
(c) Erythrocyte protoporphyria
(d) 24-hour urine for porphyrin

Answer 19

(d) 24-hour urine for porphyrin

Question 20

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

(a) ALA dehydrase
(b) Bilirubin synthetase
(c) PGB deaminase
(d) Uroporphyrinogen synthase

Answer 20

(a) ALA dehydrase