porphobilinogen

[ pôr′fō-bī-lĭnə-jən, -jĕn′ ]

n.

A porphyrin precursor found in large quantities in the urine in cases of acute or congenital porphyria.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.