Diagnosis
As porphyria is very uncommon it is often missed or wrongly diagnosed by doctors. Diagnosis is difficult because most symptoms are non-specific, such as abdominal pain, and can often be caused by many other conditions. Even for people with porphyria, it is possible that symptoms can be caused by other underlying problems.
The way in which porphyrins accumulate and the enzyme deficiency that causes this to happen is unique to each porphyria. The doctors treating you cannot make a diagnosis or even distinguish between the various forms based on physical symptoms alone. They will have to carry out appropriate biochemical investigations and correctly interpret the results of these to identify which form of the disease you have.
Tests will examine the following:
- urine test – if you have a form of acute
porphyria, a urine test may reveal elevated levels of porphobilinogen and aminolevulinic acids, as well as other porphyrins. It is likely that your urine sample will be sent to a specialised laboratory for this test.
blood test – if you have a form of cutaneous porphyria, a blood test may show an elevation in the level of porphyrins in the clear, liquid part of your blood (plasma).
stool sample test – analysis of a stool sample may reveal elevated levels of some porphyrins that may not be detected in urine samples. This test may help doctors to determine the specifi c type of porphyria affecting you.
Since most types of porphyria are inherited, investigations should also be carried out on children and blood relatives of affected people.