Hereditary Coproporphyria - Diagnosis

Diagnosis

The diagnosis of any porphyria is often delayed due to the rarity of the disease as well as the varied and non-specific findings that patients present with. Bedside measurement of urine porphobilinogen is recommended as a screening test for patients suspected of having an acute porphyria. Elevated porphobilinogen is indicative of an acute porphyria, and additional testing can be done to narrow down the specific type.

The identification of a specific porphyria is based on the results of laboratory findings, including blood, urine and stool tests. HCP can be distinguished from most other acute porphyrias by the cutaneous findings. VP presents similarly, but can be distinguished based on urine and stool porphyrin analysis, typically done using high performance liquid chromatography with fluorescence detection. The results of biochemical testing for porphyrias are most informative when samples are collected during an acute attack. Typically, the distinguishing metabolite for HCP and VP is the presence of protoporphyrin in the plasma and feces of individuals affected with VP.

Elevated coproporphyrin is a common finding in urine, known as coproporphyrinuria as it is the predominant porphyrin species in urine. This is a non-specific finding that is not necessarily due to an acute porphyria. Coproporphyrinuria can be caused by other stressors to the heme biosynthetic pathway, such as liver disease, lead poisoning and certain bone marrow disorders.