Chapter 49 - The porphyrias: fundamentals and laboratory assessment

Abstract

The porphyrias are a group of rare diseases that arise from abnormalities in the enzymes responsible for the biosynthesis of heme, the iron-containing prosthetic group of hemoglobin. Inherited or acquired altered activity of specific enzymes required for heme synthesis leads to overproduction of metabolic intermediates that accumulate in tissues and are excreted in body fluids. These metabolites, porphyrinogens, porphyrins, and the precursor compounds aminolevulinic acid and porphobilinogen, produce disease symptoms that guide the selection of laboratory tests for diagnosis and monitoring of porphyrin disorders.