Porphyrias

Question 1

what is the pathogenesis of porphyrias ?

Answer 1

deficiencies of enzymes in haem biosynthesis

- therefore causes an overproduction of toxic haem precursors

Question 2

state two common effects the toxic haem precursors cause ?

Answer 2

induce photosensitivity

neurotoxic

Question 3

what is the commonest porphyria ?

Answer 3

porphyria cutanea tarda

Question 4

what is the second commonest porphyria ?

Answer 4

acute intermittent porphyria

Question 5

what type of genetic disorder is acute intermittent porphyria ?

Answer 5

autosomal dominant with partial penetrance

Question 6

what gender is more affected by acute intermittent porphyria ?

Answer 6

females

Question 7

what age is most affected by acute intermittent porphyria ?

Answer 7

20-40yrs

Question 8

what is the presentation of acute intermittent porphyria ?

Answer 8

abdo pain, constipation
sympathetic over activity (increased HR and BP)
seizures, psychosis
red urine, fever, proteinuria, increased WCC, reduced Na/K

Question 9

state some precipitants of acute intermittent porphyria ?

Answer 9

P450 inducers - alcohol, OCP/HRT, AEDs
infection/stress
pre menstrual
fasting

Question 10

what two things will be increased in the urine during acute intermittent porphyria ?

Answer 10

porphobilinogen (PBG) 
Aminolevulinic Acid (ALA)

Question 11

what is the treatment of acute intermittent porphyria ?

Answer 11

analgesia - opiates
IV fluids
beta blockers
IV haematin

Question 12

what is the presentation of porphyria cutanea tarda

Answer 12

blistering skin lesions

facial hyper pigmentation and hypertrichosis (excess hair growth)

Question 13

what is the treatment of porphyria cutanea tarda ?

Answer 13

avoid sun
iron chelators
chloroquine