Porphyria

1. Porphyria Dr S Spijkerman

2. Porphyria • Aheterogenic group of inborn errors in the haem biosynthesis pathway. • An enzyme deficiency at any point in the pathway can cause accumulation of haem precursors. • These precursors cause the neuropathy which is responsible for the symptoms of the acute attacks of the disease. Different enzyme defects cause the different kinds of porphyria

3. Haem at the end of pathway → negative feedback to the rate-limiting enzyme in the pathway, called ALA synthase. • This prevents the formation of excessive precursors • Some events may trigger an acute attack in a genetically enzyme deficient (porphyric) patient in one of the following ways: • Induction of ALA synthase activity → ↑formation of precursors → accumulation due to genetically deficient enzyme (can’t cope with ↑ load). • Increase in haem demand, thus decreasing the haem pool and reducing the negative feedback on ALA synthase.

4. Haem pathway

5. Triggers

6. Table 2: Drugs

7. Clinical presentation • Chronic types cause skin reactions (bullae, rash etc) → not life threatening

8. Clinical presentation – acute attack

9. Diagnosis

10. Treatment of acute attack

11. Treatment (cont)

12. A “safe” anaesthetic technique