The detection of porphyria in photosensitive patients.

The biochemical diversity of the various porphyris often leads to incomplete investigation of photosensitive patients and porphyria may be excluded wrongly on the basis of normal urinary porphyrins alone. Establishing a biochemical referral centre for photosensitive patients suspected of having porphyria led to the diagnosis of 5 cases of porphyria cutanea tarda (PCT) and 2 cases of erythropoietic protoporphyria (EPP) among 34 patients referred by dermatologists over a period of 12 months. Iron overload was conformed in 3 the PCT patients by plasma ferritin assay. Studies on the available families of the two EPP patients revealed elevated red cell protoporphyrin levels in several clinically asymptomatic relatives.