Porphyria

Porphyria 

Updated: 02/09/2021

© Jun Wang, MD, PhD

General features
  • Non-inflammatory blistering disorder
  • Autosomal dominant except congenital erythropoietic porphyria (autosomal recessive)
  • Various systemic involvement and clinical presentation
  • Acute and chronic forms
  • Subepidermal vesicles as skin manifestation
Pathogenesis
  • Disturbance of porphyrin metabolism
  • Accumulation and increased excretion of porphyrins and precursors
Acute intermittent porphyria
  • Autosomal dominant 
  • Defects in porphobilinogen-deaminase
  • Accumulation of porphobilinogen and amino-levulinic acid
  • More common in women
  • Commonly become symptomatic around 18-40
  • Most commonly presents with neurologic dysfunctions
    • Peripheral and autonomic neuropathies 
    • Psychiatric presentations: Depression most common
    • Seizures, delirium, cortical blindness, coma, etc
  • Other clinical presentations
    • Abdominal pain: commonly epigastric colicky pain
    • Constipation
  • Usually DO NOT have skin rash
  • Diagnosis: Urine porphobilinogen > 6 mg/L during an acute attack
  • Management
    • Aim at reduce heme synthesis and production of porphyrin precursors:
      • High dose glucose
      • Hematin: once started, do not need glucose
    • Pain control
    • Other symptomatic treatments
Porphyria Cutanea Tarda
  • Most common type
  • Familial or acquired
  • Uroporphyrinogen decarboxylase deficiency 
  • Autosomal dominant if familial, due to mutation of UROD gene
  • Rarely due to congenital susceptibility of UROD inhibition, with normal gene, in acquired form
  • Clinical presentations more common in adults
  • Clinical presentations usually occurs after abnormal liver functions due to alcohol, hemochromatosis, viral infection, estrogen or other environmental factors
  • Clinical presentations
    • Most common: Skin fragility and blistering, especially sun exposed areas
    • Hypertrichosis 
    • Melasma like hyperpigmentation
    • Urine discoloration
    • Digital shortening, atrophy, and contractures in severe cases
  • Diagnosis
    • Suspected in adults with blistering lesions on sun-exposed skin
    • No neurovisceral symptoms
    • Screening test: Total porphyrin, if normal, no porphyrin
    • Plasma and urine porphyrins levels
    • Uroporphyrinogen decarboxylase activity assay
    • Molecular analysis for UROD
  • Management
    • Sun light avoidance
    • Cessation of alcohol, tobacco, etc
    • Adjust estrogen therapy if needed
    • Other management focused on underlying disorders, such as hemochromatosis
    • Hydroxychloroquine or chloroquine


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