I have been doing a literature review of porphyria. There is a lot of literature that states PBG levels is the indicator for determining that a person is having an acute attack. But this does not seem to be consistent with lived experiences or several case studies and not all types of porphyria have elevated PBG.
Karen
At the Norwegian Porphyria Centre (NAPOS) we have experienced several times that patients with diagnosed and manifest porphyria have had negative urinary ALA and PBG taken shortly after clinical symptom that the patients themselves interpreted as an acute attack. Their abdominal pain or other symptoms must, however be due to other causes than an acute porphyria attack.
Pathogenesis of the acute attack
In the acute porphyrias it is believed that the acute attack is the result of hyperinduction of the haem synthetic pathway. In response to a trigger factor, the rate-limiting enzyme ALAS-1 is derepressed, resulting in is a massive flux of porphyrinogens and their precursors through the haem synthetic pathway which in turn results in the elevated levels of ALA and PBG.
Diagnosis of the acute attack
It is essential that the acute attack is always confirmed by the appropriate biochemical tests. The most reliable test is demonstration of elevated urinary ALA and PBG levels by a quantitative technique.
Making a diagnosis of the acute attack of porphyria on clinical grounds alone frequently leads to misidentification and the labeling of patients as having acute attacks when in fact they have nothing of the sort.
I agree with Dr. Brun's response. It wouldn't be unusual for people to be labelled as having acute porphyria without undergoing the appropriate biochemical testing. There exists a limitation of certain laboratories in not being able to process the body fluid samples(for PBG, ALA) correctly - possibly from the infrequency of these tests being ordered or errors in sending the sample to the lab. The sample should also be obtained when the person is having symptoms in order to increase its yield.
Despite decades of porphyria research, a lot remains to be learned about this disorder. As an example, the American Porphyria Foundation (apf.org) has been working with the NIH and our Porphyrias Consortium in generating studies.
As an aside, there will be an International Congress on Porphyrins and Porphyrias in September 2015 at Dusseldorf.
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