Porphyria

Overview

Porphyria refers to a group of mostly inherited disorders that affect how the body makes heme, an essential part of hemoglobin, the molecule that carries oxygen in red blood cells. Heme is built in several steps, each helped by a specific enzyme. In porphyria, one of these enzymes does not work well, so substances called porphyrins or their precursors build up and cause symptoms.

There are several types of porphyria, generally divided into two broad groups. Acute porphyrias mainly affect the nervous system and can cause sudden attacks, while cutaneous porphyrias mainly affect the skin, often making it sensitive to sunlight. Some types cause both. Symptoms vary widely, and many people have triggers that bring on episodes. With diagnosis and management, most people can reduce attacks and control symptoms.

Symptoms

Symptoms depend on the type of porphyria.

• Acute porphyrias (nervous system): Episodes of severe abdominal pain, nausea and vomiting, constipation, muscle weakness, numbness or tingling, rapid heartbeat, high blood pressure, confusion, anxiety, and sometimes seizures. Urine may turn reddish or brown during an attack.
• Cutaneous porphyrias (skin): Skin that is fragile or sensitive to sunlight, with blisters, redness, swelling, itching, or scarring on sun-exposed areas.

Acute attacks can be severe and even life threatening, and they require urgent medical care. Between attacks, many people feel well.

Causes

Most porphyrias are caused by inherited changes in the genes that provide instructions for the enzymes used to make heme. When an enzyme is deficient, porphyrins or their precursors accumulate. One common type that affects the skin can also be acquired and is linked to factors that affect the liver.

Even in inherited forms, many people who carry a gene change never develop symptoms unless something triggers an attack. Common triggers include certain medications, fasting or crash dieting, alcohol, infections, stress, hormonal changes, smoking, and, for skin types, sun exposure.

Risk Factors

• A family history of porphyria
• Carrying an inherited gene change affecting heme production
• Use of medications that can trigger acute attacks
• Fasting, crash dieting, or low calorie intake
• Alcohol use and smoking
• Hormonal changes, such as during the menstrual cycle
• Liver-related factors for some skin types

Diagnosis

Porphyria can be difficult to diagnose because symptoms overlap with many other conditions. Testing usually involves measuring porphyrins and their precursors.

• Urine, blood, and stool tests: To measure porphyrins and related chemicals, which is most useful during or soon after an attack for acute types.
• Specialized testing: To identify the specific type of porphyria.
• Genetic testing: To confirm an inherited form and help test family members.

Testing during symptoms improves accuracy for acute porphyrias, so it is important to be evaluated promptly during an attack.

Treatment

Treatment depends on the type and focuses on relieving symptoms, treating attacks, and preventing future episodes.

• Acute attacks: Treated in the hospital with measures that may include intravenous glucose, specific medication to reduce porphyrin production, fluids, pain control, and monitoring, since severe attacks can be dangerous.
• Avoiding triggers: Stopping or avoiding medications and other triggers known to provoke attacks.
• Cutaneous types: Sun protection, including clothing and avoiding sunlight, and treatments aimed at reducing porphyrin levels.
• Long-term management: Sometimes ongoing treatments to prevent recurrent attacks, and care from a specialist.

Prevention

You cannot prevent inherited porphyria, but you can reduce attacks and symptoms by avoiding triggers:

• Carry a list of safe and unsafe medications and share it with all your clinicians
• Avoid fasting and eat regular, balanced meals
• Limit or avoid alcohol and avoid smoking
• Protect your skin from the sun if you have a cutaneous type
• Manage stress and treat infections promptly
• Consider genetic counseling for affected families

When to See a Doctor

See a doctor if you have unexplained recurring severe abdominal pain, especially with muscle weakness, numbness, or confusion, or if you have skin that blisters easily in sunlight. Seek emergency care during an acute attack, particularly if you have:

• Severe abdominal pain with vomiting
• Muscle weakness, difficulty breathing, or trouble moving
• Confusion, hallucinations, or a seizure
• A very fast heartbeat or signs of dehydration

Tell emergency staff if you have porphyria, since some medications can worsen an attack.

Related Topics

Frequently Asked Questions

References

1. American Porphyria Foundation.
2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Porphyria.
3. MedlinePlus, U.S. National Library of Medicine. Porphyria.
4. Genetic and Rare Diseases Information Center (GARD), National Institutes of Health.