By Afsaneh Khetrapal, BSc (Hons)
Porphyria cutanea tarda (PCT) is a common form of hepatic porphyria characterized by symptoms such as fragile, blister-prone skin particularly on sun-exposed areas.
The condition occurs due to an acquired or inherited deficiency in the activity of hepatic uroporphyrinogen decarboxylase (UROD), an enzyme in the heme biosynthetic pathway. This deficiency leads to the accumulation of porphyrins – this is common in states of increased oxidative stress in the hepatocytes usually due to increased hepatic iron or less commonly alcohol, smoking, estrogens, or viral infections.
There is no established cure for PCT; however, it is still considered as one of the most manageable porphyrias and the prognosis is very promising. The treatment approaches include:
- Phlebotomy – this is the frontline treatment for PCT. The procedure involves blood removal via a vein. As the red blood cells contain such a considerable proportion of the body’s iron repeated phlebotomies (venesection) can be effective in lowering the body’s iron levels. Nearly 0.5 L blood is removed every 1-2 weeks until hemoglobin and iron levels drop to within normal physiological range. Improvement could take 12-24 weeks.
- Sun Protection – avoidance of the sun is recommended whenever possible in addition to using sufficient protection (opaque sunscreen and appropriate clothing) when outside. This is because porphyrins are known to efficiently absorb radiant energy of very long ultraviolet and visible light wavelengths.
- Anti-malaria Treatment – this is generally seen as an option when the patient is not eligible for phlebotomies, e.g. if the patient is anemic. A low dosage regime of chloroquine (125mg) or hydroxychloroquine (100mg) is recommended twice a week to reduce excess hepatic porphyrins. The dosage is decided such that it is not high enough to expel porphyrins too rapidly, transiently exacerbate PCT and induce liver damage before a remission of PCT is seen.The precise mechanism by which these drugs act with respect to PCT has yet to be determined. However, it is plausible that they bind with lysosomal porphyrins in the hepatocytes until they are eventually expelled through the urine.
- Iron Awareness – whilst foods high in iron do not usually aggravate PCT significantly, it is strongly recommended that dietary supplements containing iron are ceased. Additionally, Vitamin C intake should be adequate as this is necessary for iron absorption in the body.
- Avoidance of Environmental Triggers – a well-established example of a trigger is alcohol which not only exacerbates Hepatitis C infection greatly and inflicts liver damage, but may also worsen PCT. Other triggers include the smoking of cigarettes or pharmaceutical intake of estrogen (in birth control tablets) which may induce a bout of PCT.
- Antiviral treatment – the treatment of concomitant Hepatitis C infection with interferon alpha and ribavirin therapy has been shown to be favorable in some with PCT by resulting in a decrease in cutaneous lesions. That said, it appears that PCT should be addressed before hepatitis infection.
- Treatment of HIV infection might also be considered in PCT patients due to the association between the conditions.
- Iron chelators – These are drugs that bind to iron in the body and alter its water solubility to allow its expulsion through the kidneys. Therapy with iron chelators is less effective than phlebotomy or anti-malarials in treating PCT cases. Despite this, it may have a role in treating a subsection of affected individuals, e.g. individuals suffering from end stage renal disease require hemodialysis and are therefore not suitable for phlebotomy.
Reviewed by Susha Cheriyedath, MSc
Last Updated: Jun 24, 2016