ADAM Health Encyclopedia

Porphyria

Definition

Porphyrias are a rare group of disorders passed down through families in which an important part of hemoglobin, called heme, does not develop properly. Heme is also found in myoglobin, a protein found in certain muscles.

Alternative Names

Causes

Normally, the body breaks down chemicals, called porphyrins, into heme. The porphyrins leave the body through urine or stools. But persons with porphyria have a genetic defect that interrupts this process. As a result, porphyrins build up in the body. This can lead to rashes, light sensitivity, abdominal pain, and other symptoms.

There are many different forms of porphyria. The most common type is porphyria cutanea tarda.

Drugs, infection, alcohol, and hormones such as estrogen may trigger attacks of certain types of porphyria.

Symptoms

Porphyrias involve three major symptoms:

• Abdominal pain or cramping (occurs in only some forms of the disease)
• Light sensitivity causing rashes (photodermatitis)
• Problems with the nervous and muscular systems

Attacks can occur suddenly, usually with severe stomach pain followed by vomiting and constipation. Being out in the sun can cause pain, sensations of heat, blistering, and skin redness and swelling. Blisters heal slowly, often with scarring or skin color changes, and may be disfiguring. Urine may become red or brown following an attack.

Other symptoms that may occur include:

• Muscle pain
• Muscle weakness or paralysis
• Numbness or tingling
• Pain in the arms or legs
• Pain in the back
• Personality changes

Acute attacks can sometimes be life threatening, producing severe electrolyte imbalances, low blood pressure, and shock.

Exams and Tests

Your doctor will perform a physical exam, which includes listening to your heart. You may have tachycardia. The doctor may find that your deep tendon reflexes (knee jerks) do not work properly.

Blood and urine tests may reveal kidney problems or other problems. The PROTO blood test can measure porphyrins in the blood.

Some of the other tests that may be done include:

• Blood gases
• BUN
• Enzyme assay for specific porphyrins and other chemicals linked to this condition
• Creatinine clearance
• Serum creatinine
• Serum potassium
• Urinalysis

Treatment

Some of the medicines used to treat a sudden (acute) attack of porphyria may include:

• Hematin given through a vein (intravenously)
• Pain medication
• Sedatives to help you feel sleepy and less anxious
• Propranolol to control the heart beat

Other treatments may include:

• Fluids and glucose to boost carbohydrate levels, which helps limit the production of porphyrins
• Phlebotomy (removal of blood)
• Beta-carotene supplements

Depending on the type of porphyria you have, your doctor may tell you to:

• Avoid all alcohol
• Avoid drugs that may trigger an attack
• Avoid injuring the skin
• Avoid sunlight as much as possible and use sunscreen when outside
• Eat high-carbohydrate diet

Outlook (Prognosis)

Porphyrias are life-long diseases with symptoms that come and go. Some forms of the disease cause more symptoms than others. Proper treatment and avoidance of triggers can help reduce the time between attacks.

Possible Complications

• Coma
• Gallstones
• Lung failure
• Loss of movement (paralysis) that gets worse
• Scarring of the skin

When to Contact a Medical Professional

Seek medical attention as soon as you have signs of an acute attack. Talk to your doctor about your risk for this condition if you have a long history of undiagnosed abdominal pain, muscle and nerve problems, and sensitivity to sunlight.

Prevention

Genetic counseling may be of benefit to prospective parents with a family history of any type of porphyria.

Hoffman R, Benz EJ, Shattil SS, et al. Hematology: Basic Principles and Practice. 4th ed. Orlando, Fl: Churchill Livingstone; 2005.

Dombeck TA. The porphyrias. Emerg Med Clin North Am. Aug 2005; 23(3): 885-99, x.