| Acute Porphyrias
| Variegate Porphyria
| Acute Intermittent Porphyria (AIP)
| Porphyria Cutanea Tarda (PCT)
| Porphyria Testing
PCT causes blistering of the backs of hands and the forehead which usually heals with a small scar and milia formation. Autosomal dominant inheritance of a single mutation of the UROD gene.
- Porphyrins produced in PCT are photoactive molecules that absorb light energy strongly in the visible violet spectrum.
- Photoexcited porphyrins in the skin mediate oxidative damage to biomolecular targets, causing cutaneous photosensitivity reactions.
- Deficient activity of the heme-synthetic enzyme uroporphyrinogen decarboxylase (URO-D) in the liver.
- 80% of all cases are acquired; 20% are familial
- Autosomal dominant inheritence
- Overproduction of porphyrins accumulate in the liver and plasma
- Blistering Photosensitive eruption worsens to light exposure
- Hypertrichosis and milia formation (keratin-containing cysts)
- Fragility of sun-exposed skin after mechanical trauma
- Leads to erosions and bullae, worst on dorsal hands, forearms and face
- Urinary porphyrin levels are high in PCT in a 24-hour period. The porphyrin pigment is often grossly evident in visible light and yields a pink fluorescence under Wood lamp (black light) radiation
- Faecal coproporphyrin fraction is often abnormally high
- Measure UROD enzyme activity assay in red blood cells where available
- Avoid sunlight, alcohol and smoking and oestrogens
- Therapeutic phlebotomy reduces iron stores, which improves heme synthesis disturbed by Ferro-mediated inhibition of uroporphyrinogen decarboxylase (UROD).
- The goal of therapy is to reduce serum ferritin levels to the lower limit of the reference range. Ensure Hb > 11 g/dl.
- Oral chloroquine phosphate or hydroxychloroquine sulfate can be effective.
- Chelation with desferrioxamine is an alternative means of iron mobilization when venesections are not practical.
All samples collected must be protected from light. Collection Bottles: Blood - Purple EDTA, Urine - White plain 20ml universal,
Faeces - Blue Faecal 20 ml universal