Porphyria, hepatic

Porphyria, Hepatic Porphyria, hepatic, refers to a group of rare metabolic disorders that result from a deficiency of certain enzymes in the heme biosynthesis pathway, primarily affecting the liver. These disorders lead to the accumulation of porphyrins or porphyrin precursors, which can cause a variety of symptoms, particularly affecting the skin and nervous system.

Overview

Hepatic porphyrias are characterized by the overproduction and accumulation of porphyrins or their precursors in the liver. The main types of hepatic porphyrias include:

• Acute Intermittent Porphyria (AIP)
• Hereditary Coproporphyria (HCP)
• Variegate Porphyria (VP)
• Porphyria Cutanea Tarda (PCT)

Each type is associated with a specific enzyme deficiency in the heme biosynthesis pathway.

Pathophysiology

The heme biosynthesis pathway involves eight enzymatic steps, and deficiencies in these enzymes lead to the accumulation of porphyrins or their precursors. In hepatic porphyrias, the liver is the primary site of overproduction. The accumulation of these compounds can cause:

• Neurovisceral attacks, characterized by abdominal pain, vomiting, and neurological symptoms.
• Photosensitivity, leading to skin damage upon exposure to sunlight.

Symptoms

The symptoms of hepatic porphyrias can vary depending on the specific type but often include:

• Severe abdominal pain
• Neurological disturbances such as seizures, confusion, and peripheral neuropathy
• Hypertension and tachycardia
• Skin lesions and blistering in response to sunlight (in some types)

Diagnosis

Diagnosis of hepatic porphyrias involves:

• Measuring porphyrins and their precursors in urine, blood, and stool.
• Genetic testing to identify specific enzyme deficiencies.
• Clinical evaluation of symptoms and family history.

Treatment

Management of hepatic porphyrias includes:

• Avoidance of triggering factors such as certain drugs, alcohol, and fasting.
• Administration of glucose or hemin to reduce porphyrin production during acute attacks.
• Symptomatic treatment for pain and neurological symptoms.

Prognosis

The prognosis for individuals with hepatic porphyrias varies. With proper management and avoidance of triggers, many patients can lead relatively normal lives. However, acute attacks can be life-threatening and require prompt medical attention.

Research and Future Directions

Ongoing research aims to better understand the genetic and biochemical basis of hepatic porphyrias, develop new treatments, and improve diagnostic methods. Gene therapy and enzyme replacement are potential future therapies under investigation.

See Also

• Heme Biosynthesis
• Porphyrin
• Photosensitivity

External Links

• [American Porphyria Foundation](https://www.porphyriafoundation.com/)
• National Organization for Rare Disorders

NIH genetic and rare disease info

• NIH info on Porphyria, hepatic

Porphyria, hepatic is a rare disease.