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Porphyria

Definition

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

Alternative Names

Acute intermittent porphyria; Hereditary coproporphyria; Congenital erythropoietic porphyria; Erythropoietic protoporphyria

Causes, incidence, and risk factors

Normally, the body makes heme in a multi-step process. Porphyrins are made during several steps of this process. Patients with porphyria have a deficiency of certain enzymes needed for this process. This causes abnormal amounts of porphyrins or related chemicals to build up in the body.

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

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 (only in some forms of the disease)
• Light sensitivity causing rashes, blistering, and scarring of the skin (photodermatitis)
• Problems with the nervous system and muscles (seizures, mental disturbances, nerve damage)

Attacks can occur suddenly, usually with severe abdominal 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. They may be disfiguring. Urine may turn red or brown after an attack.

Other symptoms may include:

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

Attacks can sometimes be life threatening, producing:

• Low blood pressure
• Severe electrolyte imbalances
• Shock

Signs and tests

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

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

Some of the other tests that may be done include:

• Blood gases
• Comprehensive metabolic panel
• Porphyrin levels and levels of other chemicals linked to this condition (often checked in the urine)
• Ultrasound of the abdomen
• 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
• Propranolol to control the heartbeat
• Sedatives to help you feel sleepy and less anxious

Other treatments may include:

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

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 a high-carbohydrate diet

Support Groups

Expectations (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 prolong the time between attacks.

Complications

• Coma
• Gallstones
• Paralysis
• Respiratory failure (due to weakness of chest muscles)
• Scarring of the skin

Calling your health care provider

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 benefit people who want to have children and who have a family history of any type of porphyria.

References

Anderson K. The porphyrias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 229.

Wiley JS, Moore MR. Heme biosynthesis and its disorders: porphyrias and sideroblastic anemias. In: Hoffman R, Benz EJ Jr., Shattil SJ, et al, eds. Hoffman Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingstone Elsevier; 2008:chap 38.