1. Labelled glycine and/or δ-aminolaevulinic acid (ALA) were administered to a child with congenital erythropoietic porphyria (Günther's disease), to three normal children and to three patients with erythropoietic protoporphyria.
2. The utilization of [15N]ALA for the synthesis of faecal ‘urobilin’ in the congenital erythropoietic patient was normal.
3. This suggests there is no significant increase of hepatic bile-pigment formation in congenital erythropoietic porphyria.
4. The utilization of glycine for synthesis of faecal ‘urobilin’ and protoporphyrin in all three patients with erythropoietic protoporphyria was increased. There was a similarly high utilization of [4-14C]ALA administered either orally or intravenously to one of the patients.
5. The utilization of [4-14C]ALA was not affected by phlebotomy.
6. Utilizations of both ALA and glycine for free erythrocyte and plasma protoporphyrins were low.
7. This study provides further evidence that in erythropoietic protoporphyria there is a greatly increased hepatic contribution to the early labelled fraction of bile pigment and that in this disease the excessive protoporphyrin is formed mainly in the liver.