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Hereditary Coproporphyria

This information is being sent to you by the Canadian Association for Porphyria because you have, or believe you may have, hereditary coproporphyria (HCP). The information here is intended to apply to HCP in general and may include information which does not apply to your specific case. Hereditary coproporphyria (HCP) is rare in all parts of the world and less is know about it than about some of the other porphyrias. However, it is probable that some people who have inherited the gene for HCP will live their lives without problems from this condition.

How does the condition present?
Hereditary coproporphyria shows itself in 2 ways, as "acute attacks" (see below) and as skin problems. There may be a family history and this must be a blood relative. The name hereditary coproporphyria is used simply because it describes a laboratory finding in an inherited condition. 

Acute attacks of porphyria
Abdominal pain, nausea, vomiting and loss of appetite are the most frequent symptoms and are often accompanied by constipation and a fast pulse rate. The urine may be dark or it may darken on standing, particularly in sunlight. The abdominal pain is difficult to describe and does not closely fit descriptions for other diseases. It is important to avoid unnecessary surgery in an attempt to diagnose the cause of the pain.

Patients with HCP will usually not experience anything more severe than the symptoms listed above: let's call this " Stage 1 ". Beyond stage 1 the events to be described are quite rare.

Stage 2
There will be a change in the level of consciousness and various abnormalities of mental function. Problems may arise with salts and water in the body (technically called "hyponatremia"). The abdominal pain, vomiting, etc. may become worse.

Stage 3
Muscle weakness may develop. Nerves supplying both muscles and sensation do not conduct properly and the disturbances of brain function listed under stage 2 become more severe. Finally, the muscles that govern breathing may become paralyzed and under these circumstances, death is possible unless the patient is supported in a hospital. 

Stage 4
This is the stage of recovery. Recovery from stages 1 and 2 (above) will be complete. However, if the peripheral nerves have been affected, i.e. if muscles weakness has developed during the acute attack of HCP, some residual paralysis may remain and this may take from one-half to three years for recovery to be complete. In the occasional patient it may never be complete.

It cannot be over-stressed that the events described in stages 2, 3, and 4 are uncommon today and your chance is small of suffering such severe illness once you know you have HCP, are properly treated, and take reasonable precautions.

Skin Problems in Hereditary Coproporphyria
You may have family members who have had porphyria diagnosed (family history). You may have noticed blisters or open sores on the backs of your hands, on your face or on other sun-exposed areas of your body, or you may have suffered sunburn after an unusually short exposure to sunlight, or to sunlight exposed through glass. 

How is HCP diagnosed?
In hereditary coproporphyria the commonest situation is for neither skin problems nor acute attacks to occur, but either or both can occur in any one patient. When HCP is suspected, laboratory tests may be performed. During an acute attack, the laboratory tests will show increased aminolevulinic acid and porphobilinogen in the urine and at all times, patients with hereditary coproporphyria have increased porphyrin in their blood, in their urine, and in their stool. The particular porphyrin the laboratory looks for in HCP is coproporphyrin and the test on a stool sample is most important. At the present time no enzyme tests are easily available to diagnose HCP, even if uncertainty remains after blood, urine and stool has been examined.

What precautions should I take to avoid acute attacks of porphyria?
Part of the answer is "we don't know ", but there are important things we do know. One of these is that acute porphyria seems to have become a problem after the introduction of manmade organic chemicals as drugs in the late 19th century. Second, some drugs (barbiturates, sulfonamides, antiepileptic drugs, and a few others) will definitely precipitate acute porphyria in a person who carries the gene for HCP. Some women have clearly experienced acute attacks, usually to the "stage 1" severity at the time of their menstrual periods or in the middle of the menstrual cycle. There is clear evidence in some women of a relationship to hormone changes in the body, but exactly what changes precipitate the condition is not clear.

There is some evidence that starvation is particularly bad for patients with HCP and you should avoid going without food for more than 12 hours if possible, particularly, you should avoid diets which involve stringent reductions in food intake or fasting. Alcohol appears to be harmful to some patients with HCP, and it would be prudent to abstain from alcohol. There is reason to belive that cigarette smoking may be deleterious and there are, of course, many reasons for avoiding cigarettes. There are one or two accounts of acute porphyria being precipitated by exposure to sunlight; the reason for this is not understood, but sunbathing is a stress on the body which changes the secretion of some hormones and again, it would be wise to avoid this risk.

It is much easier to indicate what drugs are definitely bad than to say what drugs are definitely safe, in fact, this is almost impossible to do. We live in a society which tends to accept the idea of "a pill for every ill" and if you have the gene for HCP, you should avoid taking any drugs whether purchased in the pharmacy, over the counter, or given you by your doctor, unless you have a serious condition which requires to be treated. Do not take any drugs for trivial complaints like headache, etc.

What should I do if I think I am developing an acute attack of porphyria?
Let's deal with the acute attack first, because this is the most important situation where the diagnosis must be right and must be made fast. If you have acute porphyria, your urine will always contain increased amounts of aminolevulinic acid and porphobilinogen (see above). There is an easy test for the first of these but there is an easy test for porphobilinogen called "Watson-Schwartz" test. If it is suspected that you have abdominal pain or some other symptom due to acute porphyria, this test must be positive. If porphobilinogen cannot be measured in the hospital where you are, either the test must be run immediately somewhere else, or you should be transferred. If the porphobilinogen test is negative, some other cause for the symptoms must be sought. Further, the severity of the acute attack can be followed by observing daily porphobilinogen level in urine.

Will my children be affected?
Whether you are male or female, any child of yours has a 50% chance of inheriting the gene which determines HCP. Presently (1990), this cannot be recognized by laboratories in Canada unless abnormal amounts of porphyrins are found in blood or stool. This does not occur before puberty in girls or boys. Even after puberty, tests may fall within the ranges accepted as normal in individuals who, later on, do develop positive tests. This means that when a family is tested, falsely-negative results are possible. Better procedures are available in research laboratories and will become more widely available.

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