Porphyria Flashcards
PCT
Defect in?
Caused by?
Most common hepatic porphyria
Inherited defect in uroporphyrinogen decarboxylase
Caused by hepatocyte damage e.g. alcohol, Hep C, oestrogens
PCT
Features
Photosensitive rash with blistering skin fragility on the face and dorsal aspects of the hands
Hypertrichosis
Hyperpigmentation
PCT
Ix
Urine:
Elevated uroporphyrinogen and pink fluorescence under Wood’s lamp
PCT
Mx
Chloroquine
Venesection
AIP
Defect in?
Results in?
Presents with?
AD
Defect in porphobilinogen deaminase and ?HMB synthase
Results in toxic accumulation of delta aminolaevulinic acid and porphobilinogen
Presents with abdominal and neuropsychiatric symptoms in 20-40y/o
More common in F (5:1)
AIP
Features
Abdo: abdo pain and vomiting
Neuro: motor neuropathy
Psychiatric: e.g. depression
Hypertension and tachycardia are common
AIP
Dx
Urine turns deep red on standing
Raised urinary porphobilinogen
Assay of red cells for porphobilinogen deaminase
Raised serum levels of delta aminolaevulinic acid and porphobilinogen
Hereditary Coproporphyria
Defect in?
Acute porphyria
Coproporphyrinogen oxidase
Autodomal dominant
Acute neurovisceral attack
Skin lesions:
- Blistering
- Skin fragility
Variegate Porphyria
Defect in?
Acute porphyria
Protoporphyrinogen oxidase
Autosomal dominant
Acute attacks
Skin lesions
Congenital eryrthopoietic porphyria
Defect in?
Non-acute porphyria
Uroporphyrinogen III synthase
Erythorpoietic protoporphyria
Defect in?
Non-acute porphyria
Ferrochetolase
Photosensitivity only, no blisters
Only erythroid cells affected, therefore need to measure RBC protoporphyrin
AIP
Precipitating factors
ALA synthase inducers:
Barbiturates, steroids, ethanol, anticonvulsants
Stress:
Infection, surgery
Reduced caloric intake
Endocrine factors:
More common in women and premenstrual
AIP
Tx
Avoid attacks:
Adequate nutritional intake
Precipitant drugs
Prompt treatment infection/illness
iv carbohydrate
iv haem arginate
