Porphyria Health Article

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

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

Causes, incidence, and risk factors

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.

Signs 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