This page describes the synthesis, degradation and excretion of porphyrins, and some related topics in medical biochemistry. It includes information on porphyrin chemistry, the regulation of the porphyrin biosynthetic pathway, some of the diseases associated with porhyrin metabolism and the medical use of porphyrin compounds for photodynamic therapy. Information on other aspects of nitrogen metabolism can be found in the pages on amino acids and nucleotides. Click here to skip over the detailed contents section.