Porphyria Cutanea Tarda - Canadian Porphyria Foundation

This information is being sent to you by the Canadian Association for Porphyria because you have, or believe you may have, porphyria cutanea tarda (PCT). The information here is intended to apply to PCT in general and may include information which does not apply to your specific case.

The "jaw breaker" of a name means chronic porphyria affecting the skin and it is probably the most confusing kind of porphyria. The trouble is that the skin problem referred to as "PCT" is exactly the same as a skin problem which occurs in two clearly inherited types of porphyria, variegate porphyria and hereditary coproporphyria. Nevertheless, the name is used to describe the skin symptoms of the two in inherited conditions and also a quite separate disease which is, as we shall see, quite benign. In these notes the term "porphyria cutanea tarda" will be used only to refer to this disease and not to the symptoms seen in other types of porphyria.

How do I know if I have PCT?
Usually there is no family history, even though we know that the tendency (NOTE: NOT the disease itself) to develop the disease is inherited. There will be the characteristic skin problem: water blisters and sores which heal poorly on the backs of the hands, the face and other sun-exposed areas on the body. There will often be an increased growth of fine hair on the face. The urine may have a reddish tinge, particularly in the morning, and usually there is a cause which may be a heavy alcohol intake, the use of oral contraceptive preparations or synthetic estrogens (female sex hormones) taken for therapeutic purposes. Examples of this would be after the female menopause or in men for treatment of cancer of the prostate. A further possible cause is exposure to chemicals in the work place although this is a most unlikely cause at the present time.

Finally, we come to the laboratory tests which confirm the presence of PCT. Porphyrin in the urine must be increased about 5-10 times above normal and the principal porphyrin found is uroporphyrin. However, if the disease is very active, the urine will also contain significant amounts of coproporphyrin and other porphyrins which come between uroporphyrin and coproporphyrin in the body's process of making these substances. Further, if the disease is active there will be an abnormal amount of porphyrin in the stool and this is where confusion with variegate porphyria and hereditary coproporphyria comes in. Only a few laboratories are able to distinguish the specific porphyrins in the stool which must be distinguished if the correct diagnosis is to be made. Of course, VP and HCP are inherited conditions and if neither mother nor father of the patient has an abnormal stool porphyrin, these conditions are unlikely and PCT becomes much more likely.

In most instances, an accurate diagnosis will be made by recording the history of the disease, identifying a precipitating toxin (alcohol, oral contraceptive, etc. ) and by finding a large increase in urine porphyrin with a relatively normal stool porphyrin.

Is porphyria cutanea tarda dangerous?
No, it is not, it is more a nuisance than anything else although the damage to the skin is a major problem for people who do rough work with their hands. Because of this, it is important that it be treated as soon as possible. There have been accounts of liver cancer developing in patients with PCT, but in Canada at least, this must be a rare event. Further, PCT is easily treated, although it must be realized that the occurrence of this problem is a warning that the liver has been subjected to a poison of some kind: if the cause is alcohol, there is a clear message that this is being abused. Note: This is not meant to imply that you are an alcoholic if you have PCT. For some patients with PCT two bottles of beer daily may be too much alcohol. It may be best to quit completely.

How is PCT treated?
To understand the treatment, you need to understand the three factors which operate to varying extents in any one patient to cause this problem. First, there is the issue of inheritance. It is clearly established that in some, perhaps 50% of patients with PCT, you are dealing with an inherited problem. The tendency to develop PCT has been inherited as a dominant characteristic from one parent. But in the remaining patients there may be no evidence for inheritance at all. Second, there is a toxic factor at work be it alcohol, the pill, synthetic estrogens, or some foreign chemical the body has been exposed to, e.g. at work. Third, there needs to be an excessive amount of iron in the liver.

In treating PCT nothing can be done about inheritance, but the toxin should be removed. When this is done, the condition probably would clear up eventually, but it may take years to do so. Excessive amounts of iron in the liver can be removed by withdrawing blood (about a pint) at regular intervals and discarding it. In making new blood the body uses iron and this will eventually take the extra iron away from the liver, permitting the PCT to improve. Finally, if patients with PCT are given a small dose of the drug chloroquine twice weekly for 3-6 months, urine porphyrin level usually return to normal and the skin heals up. However, for this effect to be permanent, removal of the offending toxin and/or the excess iron in the liver, is also required.

Will my skin get better?
Your skin will improve slowly. You should avoid exposure to sunlight until your doctor tells you that your urine porphyrin is not more than three times normal, or adopt other precautions. Your skin may never be completely normal again but certainly the tendency to blister and the open sores will heal completely and as the years pass, the effects of porphyria will become less and less noticeable.

You should understand that there are two factors which lead to the unsightly blisters and sores which occur: first, the skin is damaged because the porphyrins present absorb sunlight and the energy of the absorbed sunlight damages the skin. Second, the superficial layer of damaged skin easily separates and a water blister forms underneath this. If the blister bursts, the underlying skin is unhealthy and is slow to heal. Thus to look after your skin you should avoid exposure to sunlight and you should protect the skin from all kinds of damage.

Unfortunately, the ultraviolet light which damages your skin in porphyria is different (a longer wavelength) from the ultraviolet light which causes sunburn in other people. This means that the usual sunscreens do not work. If you want to use sunscreen, it must be one of the semi-opaque screens based on zinc oxide or titanium oxide. Alternatively, you can wear light cotton gloves when you go out in the sun or simply avoid sunlight. Some relief may be obtained if you take a drug called betacarotene which is simply the orange colouring material in carrots and other vegetables. Taking about 100mg of this harmless substance daily will give your skin a slightly orange colour but does provide some protection against the kind of ultraviolet light which causes problems in porphyria.

Will my children have PCT?
No. At worst, your children may inherit a susceptibility to develop PCT. But unless they are subjected to the same factors which have caused you to have PCT, i.e. alcohol, oral contraceptives, synthetic estrogens, etc., they are likely to live entirely normal lives in this regard.