Porphyrias

Question 1

what are porphyrias

Answer 1

a group of disorders leading to the build up of porphyrin in the body

Question 2

what is porphyrin

Answer 2

a pre-cursor protein to haem which formed haemoglobin

Question 3

what are the 4 main presentations of porphyrias

Answer 3

phytotoxic skin porphyrias

blistering and fragile skin

Acute attack

Severe congenital

Question 4

what are the 3 types of porphyria

Answer 4

Erythropoetic protoporphyria (EPP)

Porphyria cutaneous trade (PCT)

Acute intermittent porphyria

Question 5

what is porphyria cutanea tarda

Answer 5

uroprophyrinogen decarboxylase abnormality (usually acquired)

Question 6

what are some potential causes of PCT

Answer 6

alcohol excess
viral hepatitis 
oestrogens 
haemochromatosis 
hepatoma

Question 7

how do you investigate PCT

Answer 7

Wood’s lamp - shine light on urine - goes pink if excess porphyrins

Spectrophotometer - shine light through plasma, if it goes red they have PCT

can do skin biopsy

Question 8

management of PCT

Answer 8

determine the underlying cause (eg, hepatoma, cirrhosis) and treat that

Question 9

what is erythropoietic protoporphyria

Answer 9

a genetic disease due to an inherited deficiency in the FERROCHELATASE enzyme.

Question 10

how does erythropoietic protoporphyria present

Answer 10

symptoms present in childhood

uncomfortable pain/burning sensation on skin after sun exposure

later develop pitted scars, crusty thickened skin

Question 11

which porphyria has a risk of liver disease

Answer 11

erythropoietic protoporythria

Question 12

investigations for erythropoietic protoporphyria

Answer 12

UV microscopy - red blood cell fluoresence

Quantative RBC protoporphryns count

Question 13

management of erythropoietic protoporphyria

Answer 13

genetic counselling 
6 monthly LFTs 
visible light protection measures 
Porphylactic TL-01 phototherapy 
Vitamin D supplements (for those who completely avoid the sun)

Question 14

what are some visible light protection measures

Answer 14

Behavioural (eg. avoid sun)
Clothing
Environmental (shade, window films etc)
Topical sin creams

Question 15

what is acute intermittent porphyria

Answer 15

rare autosomal dominant metabolic disorder

deficiency of porphobinogen deaminase enzyme (PBG)

Question 16

how does acute intermittent porphyria present

Answer 16

GI symptoms 
Confusion, hallucinations 
urinary retention 
muscle weakness 
back, arm, leg pain