Porphobilinogen, Quantitative, Random, Urine Clinical
Information Discusses physiology, pathophysiology, and general
clinical aspects, as they relate to a laboratory test The
porphyrias are a group of inherited disorders resulting from
enzyme defects in the heme biosynthetic pathway. Depending on
the specific enzyme involved, various porphyrins and their
precursors accumulate in different specimen types. The patterns
of porphyrin accumulation in erythrocytes and plasma and
excretion of the heme precursors in urine and feces allow for
the detection and differentiation of the porphyrias. The
porphyrias are typically classified as erythropoietic or hepatic
based upon the primary site of the enzyme defect. In addition,
hepatic porphyrias can be further classified as chronic or
acute, based on their clinical presentation. The primary acute
hepatic porphyrias: acute intermittent porphyria (AIP),
hereditary coproporphyria (HCP), and variegate porphyria (VP),
are associated with neurovisceral symptoms which typically