Hereditary Coproporphyria (HCP)

This is an autosomal dominant form of hepatic Porphyria that is similar to AIP, except that some patients develop skin photosensitivity as well as acute attacks. The deficient enzyme is coproporphyrinogen oxidase.  In acute attacks, urine PBG is elevated as in AIP. Latent carriers exhibit excess coproporphyrin (especially coproporphyrin type III) in urine and stool. It should be noted that a high coproporphyrin in urine only, as an isolated finding (without elevated urine PBG or fecal coproporphyin), is nonspecific. Liver disease, which is far more common than acute porphyria, frequently causes elevation of urine coproporphyrin.  A definitive diagnosis may require DNA analysis, as described for AIP


**Diagnostic Testing for the Acute Porphyrias - Clarification of Testing Results**
Important Update - Click to view