Porphyrins, Urine (7 Analytes)

The Porphyrins, Urine (7 Analytes) panel, also known as urinary porphyrin fractionation with porphobilinogen (PBG), supports diagnosis and subtype classification of primary (inherited) porphyrias. Quantification of uroporphyrin fractions and coproporphyrins I and III together with PBG helps distinguish acute hepatic porphyrias from cutaneous porphyrias and cholestatic conditions. This assay also assists in identifying secondary porphyrinurias due to hepatobiliary disease, hemolysis, or toxic exposures, including lead, mercury, organic solvents, and certain medications. Interpretation should be integrated with the clinical picture and other biochemical studies.

Porphyrins are orange-red fluorescent tetrapyrroles generated during heme biosynthesis. Heme is produced from glycine and succinyl-CoA via δ-aminolevulinic acid and porphobilinogen intermediates. Disruption of this pathway leads to accumulation and increased urinary excretion of porphyrins and their precursors. Primary porphyrias are inherited enzyme deficiencies that produce characteristic urinary patterns of porphyrins and precursors. Secondary porphyrinurias develop in acquired conditions, including hepatobiliary disorders, hemolytic anemias, and toxic exposures such as lead, alcohol, and certain industrial chemicals. Fractionated urinary porphyrin analysis—reporting total uroporphyrins, higher carboxylated porphyrins (hepta-, hexa-, and penta-carboxyl species), coproporphyrins I and III, and porphobilinogen—enables pattern recognition for differential diagnosis and assessment of toxic effects.