The porphyrinogenic effects of kryptopyrrole in the rat and the occurrence of urinary kryptopyrrole in human hereditary hepatic porphyria.

1. Kryptopyrrole (2,4-dimethyl-3-ethyl pyrrole) was shown to elevate the urinary porphyrin excretion and the hepatic content of porphyrins in the rat. The simultaneous administration of sigma-aminolaevulinic acid increased these effects. 2. Kryptopyrrole was present in the urine of patients with hereditary hepatic porphyria, in attack and in remission, but not in those with latent porphyria.