Porphyrias

Definition: 

Porhyrias are metabolic disorders of heme synthesis, categorised by increased excretion of porphyrins or porphyrin precursors.

Porphyrias are either inherited or acquired. They are broadly classified into two major groups.

1. Hepatic: Enzyme defect lies in liver. It is classified into four porphyrias.
   i) Acute intermittent porphyria
   ii) Porphyria cutanea tarda
   iii) Hereditary coproporphyria
   iv) Variegate porphyria
2. Erythropoetic: Enzyme deficiency occurs in erythrocytes. It is classified into two porphyrias.
   i) Congenital erythropoetic porphyria
   ii) Protoporphyria