Porphyrias

The porphyrias are caused by loss (or gain, in the case of X-linked erythropoietic protoporphyria [XLP]) of specific enzyme functions in the heme biosynthesis pathway. Signs and symptoms of porphyrias are variable and nonspecific.  Porphyrias are generally classified as either acute or cutaneous, but some types can have overlapping symptoms, which can complicate diagnosis. The acute porphyrias (also referred to as acute hepatic porphyrias), which include acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), and variegate porphyria (VP), are characterized by neurovisceral attacks that can cause neurologic damage and death if not treated promptly. Individuals with any of the cutaneous porphyrias, which include porphyria cutanea tarda (PCT), congenital erythropoietic porphyria (CEP), erythropoietic protoporphyria (EPP), and XLP, can experience photosensitivity resulting from sun exposure, which can manifest as either blisters and scarring or immediate redness and pain. PCT is the most common porphyria and is most often seen in middle-aged adults; however, a child or infant who presents with photosensitivity is most likely to have EPP.

Initial testing includes porphobilinogen (PBG) measurement, urine porphyrin fractionation, and erythrocyte protoporphyrin measurements. Treatment should be initiated immediately if any first-line test result is positive. An accurate and prompt diagnosis is important during an acute attack of an acute porphyria because delayed treatment can cause permanent damage or death.  Secondary testing includes porphyrin analysis of stool and plasma. All specimens should be protected from light to preserve sample integrity. Genetic testing can provide definitive diagnosis  but is usually not required.  See the Porphyrias Testing Algorithm for testing recommendations for suspected porphyria types.

Tabs Content
Content Review: 
May 2019

Last Update: May 2019