Porphyrins are a group of compounds that are mainly synthesized in the bone
marrow. They play an important role in many chemical reactions in the
body, e.g., with proteins to build hemoglobin. They are later converted
to bile pigments mainly in the liver. Porphyrinuria (increase of
porphyrins in the urine) may be caused by chronic liver
diseases. Hepatitis C is a major cause of porphyria throughout the world
and may cause many symptoms, including excess blood iron - important in
conjunction with an interferon therapy (since elevated blood iron seems
to reduce the effect of interferon).
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. It
now appears that hepatitis C is the most common trigger of porphyria in
people who are predisposed.
Topical sunscreens do not prevent the skin lesions. Avoidance of alcohol and removal of iron by repeated phlebotomy (blood removal) or taking medication that binds to iron sometimes helps. Chloroquine (an anti-malaria drug), which removes a toxic by-product of the enzyme deficiency, may help, as well.
