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Porphyrias Flashcards

1
Q

What usually causes porphyrias?

A

Enzyme deficiencies in heme biosynthesis

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2
Q

Porphyrias result in the ______ and ________ of precursors in heme biosynthesis

A

overproduction and excretion

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3
Q

These are chemical intermediates in the synthesis of hemoglobin, myoglobin, and respiratory pigments

A

porphyrins

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4
Q

These are colorless and unstable metabolites of porphyrins

A

porphyrinogens

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5
Q

_______ is found in the urine of those with acute porphyria

A

Porphobilinogen

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6
Q

Urine with porphobilinogen is ______ when fresh, but then turns _______

A

normal
red/wine colored
(turns black if heated to 100 C w/ dilute HCl)

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7
Q

What are disorders of heme synthesis?

A

Porphyrias

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8
Q

Qualitative heme disorders are:

A

Hemoglobinopathies. Structural changes in globin molecule.

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9
Q

Quantitative heme disorders are:

A

Thalassemias

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10
Q

What are porphrins?

A

Stable colored compounds. Usually red-violet to red-brown.

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11
Q

Porphrins fluoresce at ________

A

400 nm

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12
Q

Protoporphyrin is…

A

Porphyrin found in feces

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13
Q

Coporporphyrin is…

A

porphyrin in urine and feces

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14
Q

Uroporphyrin is…

A

porphyrin in urine

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15
Q

Porphyrinogens are readily ______ to porphyrins upon exposure to ______ or ________

A

oxidized

light or oxygen

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16
Q

3 chemically altered hemoglobins:

A
  1. methemoglobin
  2. carboxyhemoglobin
  3. sulfhemoglobin
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17
Q

T/F Most porphyrias are due to complete lack of enzymes

A

False- most are just deficiencies of enzymes

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18
Q

Inheritance pattern of porphyrias

A

Autosomal dominant (with one exception)

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19
Q

Porphyrias can be ______ or _______

A

inherited or aqcuired

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20
Q

What is the inheritance pattern of Congenital Erythropoietic Porphyria (CEP)?

A

Autosomal recessive

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21
Q

Which porphyria is acquired?

A

Porphyria Cutanea Tarda

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22
Q

Where are the 2 main places heme precursors build up?

A

Bone marrow and liver

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23
Q

Erythropoietic porphyria is…

A

Heme precursors build up in marrow

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24
Q

Hepatic porphyria is…

A

Build up of precursors in liver

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25
Acquired porphyrias can be differentiated from true porphyrias by measuring what?
Urinary ALA and PBG
26
Excess of early heme precursors leads to _______ porphyria
Neuropsychiatric
27
Excess of late heme precursors causes _______ porphyria
cutaneous
28
What are 2 examples of early heme precursors?
ALA | Porphobilinogen
29
What are examples of late heme precursors?
Uroporphyrin, Coproporphyrin, Protoporphyrin
30
Regulation of this enzyme controls the rate of heme synthesis in the liver:
ALA synthase
31
The main purpose of porphyrias in the body is...
to contribute to the synthesis of heme
32
Disease states corresponding to enzyme deficiencies have been linked to every step of heme synthesis except:
ALAS
33
The diagnosis of porphyrias is made by a combo of ________ , _______ , and ________ findings
history, physical, laboratory
34
_________ is usually the presenting symptom of cutaneous porphyrias
Photosensitivity
35
ALAD porphyria is a _____ ________ disorder
rare genetic
36
What is the deficiency in ADP?
ALA dehydratase (ALAD)
37
What is precursor is measured in ADP?
ALA in urine
38
CEP stand for ______ and is a(n) ______ porphyria
Congenital erythropoietic porphyria; erythropoietic
39
AIP stands for __________ and is a(n) ________ porphyria
Acute intermittent hepatic porphyria; hepatic
40
HCP stands for ________ and is a(n) _______ porphyria
hereditary coproporphyria; hepatic
41
EPP stands for _______ and is a(n) ______ porphyria
erythropoetic protoporphyria; hepatic
42
mixed porphyrias as also known as...
Variegated porphyria (VP)
43
Accumulation of uroporphyrinogen & coproporphyrinogen in the body tissues lead to...
``` Excretion of these metabolites in urine & feces Light sensitivity (tissues mutilate when exposed) ```
44
Most common of hepatic porphyrias is:
PCT (porphyria cutanea tarda). However, is classified as erythropoietic due to skin manifestations
45
PCT is mostly ______
acquired; few may be auto-dominant
46
what is deficient in PCT?
Uroporphyrinogen decarboxylase
47
Decrease in Uroporphyrinogen decarboxylase leads to increased production of:
Uroporphyrinogen
48
Some degree of _____ damage is seem in all PCT patients
liver
49
AIP is an ________ porphyria with a _______ _______ inheritance pattern and is due to an deficiency in _______ ______.
acute autosomal dominant PBG deaminase
50
What builds up in AIP?
porphobilinogen & ALA
51
Manifestation of AIP is mostly ________ symptoms
Neurological
52
HCP is due to a deficiency of which enzyme? This leads to build up of what metabolites?
Coproporphyrinogen oxidase Coproporphyrinogen (III) PBG & ALA
53
What is deficient in EPP? What builds up?
Ferrochelatase Protoporphyrins in plasma and feces; possibly Coproporphyrinogen
54
This is the second most common porphyria
EPP
55
EEP leads to lifelong accumulation of protoporphyrins in _____
skin | light sensitivity seen
56
What is the most severe complication of EEP?
Progressive hepatic failure due to accumulation of protoporphyrins in liver
57
What enzyme is deficient in VP?
Protoporphyrinogen oxidase
58
How do we distinguish VP from EPP?
RBCs will fluoresce red in EPP RBCs in VP have normal protoporphyrin levels- no fluorescence
59
What is secondary porphyria and how is it distinguished from primary?
Secondary: Mild to moderate increase in porphyrins in urine. Not due to enzyme deficiency, but due to drugs, toxins, or other disorders. In secondary, urinary ALA will be increased but PBG normal
60
What are the 2 most common screening tests for urinary porphobilinogen?
Hoesch test | Watson-Schwartz test
61
What is the principle of the Hoesch test?
Urine + Hoesch reagent | --> if PBG present, red color is formed
62
What's the principle of the Watson-Schwartz test?
Ehrlich reagent + sodium acetate + urine | --> If PBG present, pink pigment formed with reagent
63
Generally, the cutaneous manifestations of ___ are less severe than those of ___, ___ or ___
EPP | PCT, VP, HCP
64
These three porphyrias have neurological manifestations:
AIP, VP, HCP
65
These porphyrias have cutaneous manifestations:
PCT, VP, HCP, EPP

Clin Chem (4 decks)

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