Porphp Flashcards
Porphyrins
pigments containing a ring of 4
ALA
PBG
Sites of Heme Biosynthesis
How is heme biosynthesis regulated?
ALA synthase
Heme biosynthesis pathway
What triggers acute porphyria attacks?
Uncontrolled up regulation of ALAS1
- -> lipophilic drugs and chemicals
- -> def of glucose and heme
What converts Glycine and Succinate into ALA
ALAS1
ALA and PBG are:
highly water soluble
- -> determined by number of carboxyl groups (-COOH)
- —> they have none
Where would you find ALA and PBG
Urine and Plasma
not in stool
Which precursor can be found in urine, stool and plasma?
Coproporphyrin
Which precursor is water insoluble?
Protoporphyrin
Only found in stool and plasma
Soret Band
strong absorbance at 400 nm
Red fluorescence at:
exposure at 366 nm
Red-orange fluorescence at 550-650 nm
Classification of Porphyrias
LOCATION of enz deficiency
- Hepatic
- Erythropoietic
CLINICAL PRESENTATION
- Acute (sudden, severe)
- Chronic (gradual, cutaneous)
RBC enz def Por
Hepatic Porphyrias
Most common type of porphyria
Acute Intermittent Porphyria (AIP)
- autosomal dominant
Most common Chronic Porphyria
Porphyria Cutanea Tarda (PCT)
Clinical presentation of Acute Porphyria
- red brown urine
- GIT (ab pain, vomit, constipation)
- Neurological
- Cardiovascular
Lab evaluation
Urine PBG Screen
–> rapid and readily done
–> need to collect sample during (symptomatic) attack
–> protect from light, refrigerate, adjust pH to stabilize
Random urine (first morning void)
Quantitiative screen for urine ALA and PBG
Cation ALA
Anion PBG
What reagent is used to elute
Ehrlich’s reagent
553 nm ABS
Which test does not require symptoms?
DNA genetic analysis
100% sensitivity and specificity
$$$
Family carriers
Chronic
Skin condition without neurological symptoms
Photosensitivity
