Porphyria is a condition that affects how heme is made and broken down by the body. Heme is the part of hemoglobin containing the iron atom that carries oxygen to the cells of the body.
What is going on in the body?
Hemoglobin is the main oxygen-carrying component of blood. Part of the hemoglobin molecule is a protein (the "globin"). The other part is heme, a molecule known as a porphyrin. This part is built to contain the iron atom that carries oxygen to the cells of the body.
Heme is built (synthesized) from other porphyrins in a series of stages. The porphyrins are made in various places in the body. When one of the stages in heme construction goes awry, either because the body is missing a constructing tool (an enzyme) for genetic reasons, or due to a disruption of the pathway caused by a toxin, certain porphyrins build up to abnormal levels in the body.
Porphyrias are classified by where in the body the excess porphyrins are made. They include:
erythropoietic, with extra production in the bone marrow
hepatic, with extra production in the liver
- erythrohepatic, with extra production in the bone marrow and liver
What are the causes and risks of the disease?
Most cases of porphyria are caused by genetic disorders. Some cases are caused by toxic substances, such as ingestion or exposure to lead or associated with chronic infections. Menstruation may increase symptoms in women.
What can be done to prevent the disease?
Prevention of porphyria is not always possible. Avoiding things that trigger symptoms may decrease the risk of symptoms. These triggers include:
- excessive bright sunlight
- certain medications, such as oral contraceptives, alcohol, and barbiturates
may be helpful to couples with a family history of porphyria.
How is the disease diagnosed?
The diagnosis of porphyria depends on the symptoms and what type of porphyria is suspected. Steps in diagnosis may include:
- a medical history, and history of activity or trauma
- a thorough medical exam
- blood tests, including a complete blood count or CBC, which counts the number of each kind of cell in the blood
- a blood test to measure porphyrins in the blood
- stool tests and cultures to look for any blood, infection, or porphyrins in the stool
- urine tests to check for porphyrins and lead in the urine
Long Term Effects
What are the long-term effects of the disease?
A person with porphyria may have recurrent and severe symptoms. Some forms of porphyria may lead to gallstones or chronic skin or liver problems. Electrolyte or salt imbalances in the blood can occur. If untreated, porphyria may also lead to respiratory distress, shock, and death.
What are the risks to others?
Porphyria is not contagious. It can be passed genetically to offspring.
What are the treatments for the disease?
Treatment depends on the type of porphyria. Treatment of acute, or short term, intermittent porphyria includes intravenous fluids and glucose. Other treatments may include:
strong pain medications for abdominal pain.
hematin, an enzyme inhibitor that can help prevent or treat attacks
tranquilizers to reduce anxiety
medications such as beta-carotene to reduce light sensitivity and the effects of sunlight
a diet high in carbohydrates
surgery, removal of the spleen to treat anemia
- withdrawal of offending agents such as medicines or exacerbating conditions such as sunlight to sensitive skin
What are the side effects of the treatments?
Pain medications may cause stomach upset, irritability, and drowsiness. Surgery can be complicated by bleeding, infection, or an allergic reaction to the anesthetic.
What happens after treatment for the disease?
A person with porphyria may have relapses, in which the condition worsens and symptoms return.
How is the disease monitored?
The person is monitored for relapses. Blood and urine tests may also be used to monitor the levels of porphyrins in the blood and urine. Further treatment is given when symptoms or attacks occur. Any new or worsening symptoms should be reported to the healthcare professional.
Harrison's Principles of Internal Medicine, Fauci et al, 1998
Complete Guide to Symptoms, Illness, and Surgery, Griffith, 2000
Professional Guide to Diseases, Burlew et al, 1995