Deck 20: Iron, Porphyrins, and Hemoglobin

Question 1

Which of the following compounds initially condenses to form aminolevulinic acid?

A) Coproporphyrinogen and urobilinogen
B) Glutamic acid and alanine
C) Acetylcholine and epinephrine
D) Succinyl coenzyme A and glycine

Answer 1

Succinyl coenzyme A and glycine

Question 2

What is the required oxidation state (valence) of iron that enables it to bind to a chromogen in most spectrophotometric assays?

A) +1
B) +2
C) +3
D) -3

Answer 2

+2

Question 3

Which of the following compounds chelates iron and is the immediate precursor of heme formation?

A) Uroporphyrinogen
B) Coproporphyrinogen I
C) Protophorhyrin IX
D) Urobilinogen

Answer 3

Protophorhyrin IX

Question 4

Which of the following chromogens will produce a colored complex with iron?

A) Biuret
B) Ferrozine
C) Molybdic acid
D) 8-hyroxyquinoline

Question 5

Which of the following specimens is appropriate to determine the concentration of lead in body fluids?

A) Serum
B) Cerebrospinal fluid
C) Whole blood
D) EDTA plasma

Question 6

Free erythrocyte protoporphyrin levels are useful for assessing exposure to which of the following metals?

A) Lead
B) Chromium
C) Zinc
D) Copper

Question 7

What complex makes up transferrin?

A) Apo-B·Transferrin
B) Apotransferrin·Fe³⁺
C) Lipoprotein A·Transferrin
D) Apotransferrin·Fe²⁺

Question 8

A 30-year-old male with ALA-dehydratase deficient porphyria (ADP) may present with which of the following clinical features?

A) Severe chest pain, shortness of breath, and rapid heart rate (tachycardia)
B) Abdominal pain and neurological dysfunction
C) Photosensitivity and cutaneous lesion
D) Bulging eyes, goiter in the neck, and heat intolerance

Question 9

Total iron binding capacity (TIBC) is equal to:

A) The sum of the serum iron and unsaturated iron binding capacity (UIBC).
B) The sum of the serum iron and serum ferritin.
C) The sum of the serum transferrin and transferrin saturation.
D) Serum iron minus unsaturated iron binding capacity (UIBC).

Question 10

Hemochromatosis is best described as which of the following?

A) A disorder characterized by an iron overload without associate tissue injury.
B) A genetically related disorder in which the body accumulates excess amounts of iron.
C) A genetically related disorder in which the body develops an iron deficiency.
D) A disorder characterized by an accumulation of porphyrins in the blood.

Question 11

Which of the following statements is correct when procuring specimens for measuring porphyrin compounds?

A) Do not expose the blood specimen to air for prolong period of time.
B) You must add 0.5 N hydrochloric acid to urine specimens to preserve it while storing.
C) It not necessary to collect the specimen in low actinic glassware.
D) Protect the specimen from light.

Question 12

A 40-year-old male patient with hemochromatosis often presents to his clinician with which of the following triad of symptoms?

A) Bronzing of the skin, cirrhosis, and diabetes
B) Polyuria, polydipsia, and polyphagia
C) Yellowing of the sclera of the eyes, shortness of breath, and chest pain
D) Abdominal pain, chest pain, and grayish-blue lips

Question 13

Protoporphyrins that chelate iron are called:

A) Hemin.
B) Hemoglobin.
C) Heme.
D) Hemosiderin.

Question 14

The biosynthesis of heme commences with which two compounds?

A) Glycine and succinyl CoA
B) Alanine and glycine
C) Glycerin and acetyl-CoA
D) Lysine and globulin

Question 15

A patient with acute intermittent porphyria is deficient in which enzyme?

A) Coproporphyrinogen oxidase
B) Aminolevulinic acid synthase
C) Ferrochelatase
D) Hydroxymethylbilane synthase

Question 16

What is the unique quality that many porphyrin compounds possess that allows for their detection within body tissues and in a test tube?

A) They emit gamma radiation that can be detected using a radiation sensor.
B) They fluoresce and are detected by exposing them to EMR at a specific wavelength.
C) They absorb heat and can be detected using a thermal sensor.
D) They emit an odor that is characteristic of the particular type of porphyrin.

Question 17

Heme is defined as:

A) Protoporphyrins that chelate iron.
B) Protoporphyrins that chelate lead.
C) Ferricheme associated with hydroxide.
D) The reduced form of a porphyrin.

Question 18

Which of the following laboratory test groups and results best reflects a patient with iron deficiency anemia?

A) Serum iron, decreased; serum TIBC, increased; transferring saturation, decreased
B) Serum iron, increased; serum TIBC, increased; transferrin saturation, increased
C) Serum lead, increased; serum TIBC, increased; transferrin saturation, increased
D) Serum iron, decreased; serum TIBC, decreased; transferrin saturation, decreased

Question 19

The addition of sufficient Fe³⁺ to saturate iron binding site of transferrin is referred to as which of the following?

A) Total iron binding saturation
B) Unsaturated iron binding capacity
C) Serum transferrin saturation
D) Total iron index

Question 20

Which of the following porphyria's best reflect this patient's symptoms and laboratory results?
A 42-year-old white South African male presents to his clinician experiencing acute neurological attacks and sensitivity of his skin to sunlight. The patient's urine showed PBG>ALA. Urine porphyrins analysis revealed elevation of urinary coproporphyrinogen III.

A) ALA-dehydratase deficient porphyria
B) Acute intermittent porphyria
C) Erythropoietic protoporphyria
D) Variegate porphyria

Question 21

A 25-year-old female visits her physician complaining of lethargy and wants to take a nap all of the time. Her physician orders laboratory tests and the results are shown below. Which of the following conditions best represent this patient's status?
$\begin{array}{|l|l|l|l|}\hline\text { Serum iron \( (\mu \mathrm{g} / \mathrm{dL}) \)} & \text {TIBC \( (\mu \mathrm{g} / \mathrm{dL}) \) }& \text { Transferrin saturation } (\%)& \text {Serum Ferritin \( (\mu \mathrm{g} / \mathrm{L}) \)} \\\\\hline \text { Dec }&\text { Inc }& \text { Dec }& \text { Dec} \\\hline\end{array}$

A) Thalassemia major
B) Iron deficiency anemia
C) Variegate porphyria
D) Hemochromatosis