porphyria Flashcards
most common types of porphyrias?
- acute intermittent porphyria (AIP)
- porphyria cutanea tarda (PCT)
- erythropoietic protoporphyria (EP)
- variegate porphyria (VP)
what is porphyria cutanea tarda?
-a blistering skin condition caused by a deficiency of the haem synthesis enzyme uroporphyrinogen decarboxylase causing a build up in the precursor uroporphyrinogen leading to a build up of caporporphyrinogen iii
what is there a deficiency of in porphyria cutanea tarda?
deficiency in the production of the liver enzyme:
UROPORPHYRINOGEN DECARBOXYLASE
what is the most common porphyria?
porphyria cutanea tarda (deficiency in uroporphyrinogen decarboxylase)
who is porphyria cutanea tarda most common in?
-middle aged, caucasian males
in porphyrea cutanea tarda there is a deficiency in the liver enzyme (1)________ leading to a build up in the precursor (2) _____ which forms (3)______
- deficiency in uroporphyrinogen decarboxylase
- build up of precursor uroporphyrinogen
- build up of caproporphynogen iii
presentation of porphyria cutanea tarda?
- vesiscles/ bullae/ blisters on sun exposed sites
- skin fragility
- hyperpigmentation
- hypertrichosis (hairy cheeks)
- red coloured urine
investigations for porphyria cutanea tarda?
Examine urine under WOOD’S LAMP= pink fluorescence
-porphyrin plasma levels
management of porphyria cutanea tarda?
Treat underlying disease
Lifestyle modifications:
- avoid iron, alcohol and oestrogen
- high factor sun cream/ avoidance UV exposure
If still symptomatic:
- chloroquine
- venesection
what is erythropoietic protoporphyia?
-a blistering skin condition caused by the insufficienct production of the haem synthesis enzyme ferrochelatase causing a build up of protoporphyin ix
what is there a difficiency of in erythropoietic protoporphyria?
deficiency in ferretochelatase
what is there a build up of in erythropoietic protoporphyria and why?
- deficiency in ferretochelatase
- this leads to a build up in protoporphyrin IX
presentation of erythropoietic protoporphyria?
- child crying in sunlight
- vesicles/ bullae/ blisters
- skin fragility
- solar urticaria and associated pain
due to deficiency in ferrochelatase leasing to a build up of protoporphyrin IX
investigations for erythropoietic protoporphyria?
- Flourescence of RBC
- Quantitative RBC porphyrins (raised protoporphyin levels)
- screen/ monitor for associated liver damage
what is acute intermittent porphyria?
-a severe form of porphyria resulting from reduced production of porphobilinogen deaminase (PBGD) causing a build up of hydroxymethylbilane
