- 1. Porphyrin excreted in the urine in porphyrinuria; e.g., urobilin. 2. Class name for all porphyrins containing 4 acetic acid groups and 4 propionic acid groups in positions 1 through 8. SEE ALSO: porphyrinogens.- u. I porphin-1,3,5,7-tetraacetic acid-2,4,6,8-tetrapropionic acid; formed by the action of light on uroporphyrinogen I; elevated levels observed in certain porphyrias.- u. III porphin-1,3,5,8-tetraacetic acid-2,4,6,7-tetrapropionic acid; formed by the action of light on uroporphyrinogen III; elevated levels observed in certain porphyrias.
* * *uro·por·phy·rin .yu̇r-ō-'pȯr-fə-rən n any of four isomeric porphyrins C40H38N4O16 which contain acetic acid and propionic acid groups on the porphin nucleus and are closely related to the coproporphyrins
* * *n.a porphyrin that plays an intermediate role in the synthesis of protoporphyrin IX. It is excreted in significant amounts in the urine in porphyria.
* * *uro·por·phy·rin (u″ro-porґfə-rin) the porphyrin (q.v.) produced by oxidation of the methylene bridges in uroporphyrinogen. Excessive amounts of uroporphyrin I are excreted in congenital erythropoietic porphyria, and both types I and III are excreted in porphyria cutanea tarda. See uroporphyrinogen.
Medical dictionary. 2011.