Flashcards in Porphyrias Deck (65):
What usually causes porphyrias?
Enzyme deficiencies in heme biosynthesis
Porphyrias result in the ______ and ________ of precursors in heme biosynthesis
overproduction and excretion
These are chemical intermediates in the synthesis of hemoglobin, myoglobin, and respiratory pigments
These are colorless and unstable metabolites of porphyrins
_______ is found in the urine of those with acute porphyria
Urine with porphobilinogen is ______ when fresh, but then turns _______
(turns black if heated to 100 C w/ dilute HCl)
What are disorders of heme synthesis?
Qualitative heme disorders are:
Hemoglobinopathies. Structural changes in globin molecule.
Quantitative heme disorders are:
What are porphrins?
Stable colored compounds. Usually red-violet to red-brown.
Porphrins fluoresce at ________
Porphyrin found in feces
porphyrin in urine and feces
porphyrin in urine
Porphyrinogens are readily ______ to porphyrins upon exposure to ______ or ________
light or oxygen
3 chemically altered hemoglobins:
T/F Most porphyrias are due to complete lack of enzymes
False- most are just deficiencies of enzymes
Inheritance pattern of porphyrias
Autosomal dominant (with one exception)
Porphyrias can be ______ or _______
inherited or aqcuired
What is the inheritance pattern of Congenital Erythropoietic Porphyria (CEP)?
Which porphyria is acquired?
Porphyria Cutanea Tarda
Where are the 2 main places heme precursors build up?
Bone marrow and liver
Erythropoietic porphyria is...
Heme precursors build up in marrow
Hepatic porphyria is...
Build up of precursors in liver
Acquired porphyrias can be differentiated from true porphyrias by measuring what?
Urinary ALA and PBG
Excess of early heme precursors leads to _______ porphyria
Excess of late heme precursors causes _______ porphyria
What are 2 examples of early heme precursors?
What are examples of late heme precursors?
Uroporphyrin, Coproporphyrin, Protoporphyrin
Regulation of this enzyme controls the rate of heme synthesis in the liver:
The main purpose of porphyrias in the body is...
to contribute to the synthesis of heme
Disease states corresponding to enzyme deficiencies have been linked to every step of heme synthesis except:
The diagnosis of porphyrias is made by a combo of ________ , _______ , and ________ findings
history, physical, laboratory
_________ is usually the presenting symptom of cutaneous porphyrias
ALAD porphyria is a _____ ________ disorder
What is the deficiency in ADP?
ALA dehydratase (ALAD)
What is precursor is measured in ADP?
ALA in urine
CEP stand for ______ and is a(n) ______ porphyria
Congenital erythropoietic porphyria; erythropoietic
AIP stands for __________ and is a(n) ________ porphyria
Acute intermittent hepatic porphyria; hepatic
HCP stands for ________ and is a(n) _______ porphyria
hereditary coproporphyria; hepatic
EPP stands for _______ and is a(n) ______ porphyria
erythropoetic protoporphyria; hepatic
mixed porphyrias as also known as...
Variegated porphyria (VP)
Accumulation of uroporphyrinogen & coproporphyrinogen in the body tissues lead to...
Excretion of these metabolites in urine & feces
Light sensitivity (tissues mutilate when exposed)
Most common of hepatic porphyrias is:
PCT (porphyria cutanea tarda). However, is classified as erythropoietic due to skin manifestations
PCT is mostly ______
acquired; few may be auto-dominant
what is deficient in PCT?
Decrease in Uroporphyrinogen decarboxylase leads to increased production of:
Some degree of _____ damage is seem in all PCT patients
AIP is an ________ porphyria with a _______ _______ inheritance pattern and is due to an deficiency in _______ ______.
What builds up in AIP?
porphobilinogen & ALA
Manifestation of AIP is mostly ________ symptoms
HCP is due to a deficiency of which enzyme?
This leads to build up of what metabolites?
Coproporphyrinogen (III) PBG & ALA
What is deficient in EPP?
What builds up?
Protoporphyrins in plasma and feces; possibly Coproporphyrinogen
This is the second most common porphyria
EEP leads to lifelong accumulation of protoporphyrins in _____
(light sensitivity seen)
What is the most severe complication of EEP?
Progressive hepatic failure due to accumulation of protoporphyrins in liver
What enzyme is deficient in VP?
How do we distinguish VP from EPP?
RBCs will fluoresce red in EPP
RBCs in VP have normal protoporphyrin levels- no fluorescence
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
What are the 2 most common screening tests for urinary porphobilinogen?
What is the principle of the Hoesch test?
Urine + Hoesch reagent
--> if PBG present, red color is formed
What's the principle of the Watson-Schwartz test?
Ehrlich reagent + sodium acetate + urine
--> If PBG present, pink pigment formed with reagent
Generally, the cutaneous manifestations of ___ are less severe than those of ___, ___ or ___
PCT, VP, HCP
These three porphyrias have neurological manifestations:
AIP, VP, HCP