Differentiation of porphyria cutanea tarda symptomatica from other types of porphyria by measurement of isocoproporphyrin in faeces.

The faecal porphyrin patterns of 24 patients with porphyria cutanea tarda symptomatica (PCTS), eight patients with variegate porphyria, three patients with other types of porphyria, and 20 non-porphyrics subjects have been compared using a two-demensional thin layer chromatographic technique that separates porphyrins of the isocoproporphyrin series from other faecal porphyrins. The 'isocoproporphyrin': coproporphyrin ratio ranged from 0-1 to 5-6 for patients with PCTS, whereas in other types of porphyria and non-porphyric subjects it was 0-05 or less.