The porphyrias are inherited or acquired disorders of certain enzymes in the haem biosynthetic pathway that is responsible for the synthesis of haemoglobin, myoglobin and cytochrome. They are broadly classified as hepatic porphyrias or erythropoietic porphyrias, based on the site of their overproduction and subsequent accumulation (or their chemical precursors).
Faeces protected from light, preferably collect during an attack
Up to 6 weeks
Not currently performed in house; this is a referred test.