investigations

Last reviewed 03/2022

• urine - colour and porphyrin level are diagnostic. The patient may have burgundy red urine if uroporphyrin is present and this is a constant finding in congenital erythropoietic porphyria. Urine in acute intermittent porphyria becomes brown, red or black on standing whilst that of porphyria cutanea tarda shows a pink fluorescence when illuminated. Particular porphyrins raised except in erythropoietic protoporphyria.

• serum - specific porphyrins raised except in variegate porphyria. Increase is moderate in porphyria cutanea tarda.

• stool - specific porphyrins raised except in acute intermittent porphyria.