Porphyria cutanea tarda occurs throughout the world. The disorder results from low levels of the enzyme responsible for the fifth step in heme production. . Porphyria cutanea tarda is a rare deficiency of a liver enzyme essential for cellular metabolism. The enzyme deficiency may cause sun exposed skin to blister, ulcerate, turn dark, or bruise. Hair may increase on the forehead, cheeks, or forearms, and the urine may turn pink or brown. The most common presenting sign of PCT is fragility of sun-exposed skin after mechanical trauma, leading to erosions and bullae, typically on hands and forearms and occasionally on face or feet. Porphyria cutanea tarda results from underactivity of the enzyme uroporphyrinogen decarboxylase, which leads to accumulation of porphyrins in the liver. Skin damage occurs because porphyrins produced in the liver are transported by the blood plasma to the skin. Affected people get blisters on areas of the skin which are exposed to the sun. It also makes the skin sensitive to minor trauma. Crusting and scarring can also occur and will take a long time to heal. This skin damage happens because of the metabolite porphyrin.
People with porphyria cutanea tarda also have increased iron levels in the liver. Some people are born with the condition, but in the majority it appears later in life, having been caused by a toxin affecting the liver. Additional medical problems associated with some types of porphyria include a low number of red blood cells, enlargement of the spleen, abnormal liver function, and an increased risk of developing liver cancer.Other contributing factors can be the intake of alcohol, iron supplements and oestrogen-containing medicines. Porphyria cutanea tarda is the most readily treated porphyria. Avoiding alcohol and other precipitating factors is beneficial. People with porphyria cutanea tarda experience chronic, recurring blisters of various sizes on sun-exposed areas such as the arms, face, and especially the backs of the hands. The signs and symptoms of this condition are triggered by nongenetic factors such as alcohol abuse, excess iron, certain hormones, and viral infections. Porphyria cutanea tarda is the most easily treated porphyria. The primary treatment is phlebotomy, where a pint of blood is removed every 1-2 weeks. Phlebotomy reduces the amount of iron in the patient's system, and since iron inhibits the deficient enzyme this is very helpful.
Causes of Porphyria cutanea tarda
Porphyria cutanea tarda is due to a defective enzyme in the liver (uroporphyrinogen decarboxylase). This is involved in synthesis of the red pigment in blood cells. Infection with the human immunodeficiency virus is a less common precipitating factor. These factors are thought to interact with iron and oxygen in the liver and thereby inhibit or damage the enzyme uroporphyrinogen decarboxylase.
Common causes and risk factors of Porphyria cutanea tarda:
- Heredity problem.
- Estrogens and infection with hepatitis C or human immunodeficiency virus.
- Excess alcohol intake.
- Hormone replacement or liver disease.
Signs and Symptoms of Porphyria cutanea tarda
Some types of porphyria cause the skin to become overly sensitive to sunlight. Areas of the skin exposed to the sun are fragile and easily damaged. Exposed skin may develop redness, blistering, infections, scarring, changes in pigmentation, and increased hair growth. Hair growth on the face and other sun-exposed area may increase. Liver damage usually occurs; cirrhosis and even liver cancer may eventually develop. They accumulate in the liver and are transported to the skin by the blood plasma. When porphyrins are exposed to light and oxygen, they produced a charged, unstable oxygen which is harmful to the skin.
Sign and symptoms may include the following :
- Increased sensitivity to the sun.
- Hair growth on the face and other sun-exposed area may increase.
- Chronic, recurring blisters of various sizes on sun-exposed areas such as the arms, face, and especially the backs of the hands.
- Darkening and thickening of the skin.
Treatment for Porphyria cutanea tarda
Porphyria cutanea tarda is the most readily treated porphyria. A procedure called phlebotomy, in which a pint of blood is removed, is the most widely recommended treatment. Chemicals or medicines that are toxic to the liver or are known to be capable of aggravating the condition, including iron supplements, should be avoided. When the simple avoidance of liver-toxic chemicals is not enough, the medicines chloroquine - usually used in the treatment of malaria, or hydroxychloroquine may help by reducing liver porphyrin stores.
Treatment may include:
- When the simple avoidance of liver-toxic chemicals is not enough, the medicines chloroquine, usually used in the treatment of malaria, or hydroxychloroquine may help by reducing liver porphyrin stores.
- Phlebotomy is the primary symptom in which a pint of blood is removed. With phlebotomy, the excess iron is gradually removed, the activity of uroporphyrinogen decarboxylase in the liver returns toward normal.
- Aralen and Plaquenil are also effective in treating porphyria cutanea tarda. These drugs remove excess porphyrins from the liver.