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Liz's Clinical Chemistry Module 2 > Porphyrins > Flashcards

Porphyrins Flashcards

1
Q

Two anatomical sites in the body where porphyrins are synthesized

A
  • Marrow of long bones

- Liver

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2
Q

Chemical structure of heme (# f pyrrole rings and the valence of iron)

A

Tetrapyrole ring (4 rings) w/ alpha/beta chains and iron w/ a 2+ valence

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3
Q

What is the most common porphyria?

A

Porphyria cutanea tarda

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4
Q

Enzyme deficiency in porphyria cutanea tarda

A

Uroporphyrinogen decarboxylase

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5
Q

Enzyme deficiency in acute intermittent porphyria

A

Porphobilinogen (PBG) deaminase

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6
Q

Enzyme deficiency in congenital erythropoietic porphyria

A

Uroporphyrinogen III cosynthase

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7
Q

Enzym deficiency resulting in erythropoietic protoporphyria; the enzyme necessary for the incorporation of iron in protoporphyrin X

A

Ferrochelatase

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8
Q

Porphyrinogens (reduced porphyrins)

  • Relative stability
  • Color
  • Fluorescent properties
A
  • Relative stability: unstable
  • Color: colorless
  • Fluorescent properties: non-fluorescent
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9
Q

Porphyrins

  • Relative stability
  • Color
  • Fluorescent properties
A
  • Relative stability: stable
  • Color: colored (dark red or purple)
  • Fluorescent properties: fluorescent (excite at 420nm; emission at 620nm)
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10
Q

What is the reagent used in the porphyrin screening test?

A

Ehrlich’s reagent

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11
Q

What is the best method for quantitative porphyrin assays?

A

Liquid Chromatography (LC) or LC/MS

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12
Q

3 most common porphyrias

A
  • Acute intermittent porphyria
  • Porphyria cutanea tarda
  • Erythropoietic porphyria/protoporphyria
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13
Q

Acute intermittent porphyria

- 1 typical symptom

A

Acute abdominal pain

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14
Q

Acute intermittent porphyria

- Exacerbating factors

A
  • Drugs/alcohol
  • Fasting/dieting
  • Oral contraceptives
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15
Q

Acute intermittent porphyria

- Porphyrin that is increased

A

Porphobilinogen (PBG)

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16
Q

Acute intermittent porphyria

- What happens as a urine sample from a patient is left at room temperature for at least 2 hours?

A

Urine gets darker (red/port wine color) as it sets

17
Q

What is the nickname for porphyria cutanea tarda?

A

“Vampire’s Disease”

18
Q

Porphyria cutanea tarda

- 4 typical symptoms

A
  • Fragile skin
  • Blisters
  • Scarring
  • Hyperpigmentation
19
Q

Porphyria cutanea tarda

- Porphyrin that is increased

A

Urinary uroporphyrinogen III

20
Q

Erythropoietic protoporphyria

- 2 symptoms

A
  • Painful skin

- Skin swelling (congenital or acquired)

21
Q

4 physical characteristics of a patient w/ congenital erythropoietic porphyria

A
  • Extreme photosensitivity
  • Reddish/brown teeth staining
  • Mental retardation
  • Abnormal growth patterns
22
Q

Color of urine in a patient w/ congenital erythropoietic porphyria

A

Urine is pink/red

23
Q

Two enzymes in the heme biosynthetic pathway that are inhibited in lead poisoning

A
  • ALA dehydrogenase

- Ferrochelatase

24
Q

What is typically analyzed in the lab to definitively diagnose lead poisoning?

A
  • Increased urinary delta-ALA and coproporphyrin
  • Increased RBC zinc protoporphyrin
  • Increasedlead in whole blood
25
Q

Enzyme deficiency/inhibition in lead toxicity

A

Gamma-aminolevulinic acid dehydratase

26
Q

A qualitative screening test for diagnosis of acute intermittent porphyria, in which Ehrlich’s reagent and saturated sodium acetate are added to the urine

A

Watson-Schwartz screening test

27
Q

What two substances turn pink/red upon addition of Ehrlich’s reagent in the Watson-Schwartz screening test?

A

Pink/red color indicates the presence of either porphobilinogen (PBG) or urobilinogen (UBG)

28
Q

Interpret the differential test results of the Watson-Schwartz screening test w/ both chloroform and butanol extraction

A
  • A positive PBG indicates a porphyria; in chloroform extraction, PBG is at the top b/c chloroform is heavier than water; in a butanol extraction, PBG is at the bottom
  • A positive UBG does not indicate a porphyria; in a chloroform extraction, UBG is at the bottom; in a butanol extraction, UBG is at the top

Liz's Clinical Chemistry Module 2 (9 decks)

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