I would also like to add to your wonderful summary that mercury toxicity can also be responsible for causing an excess amount of porphyrins.
Altered Porphyrin Metabolism as a Biomarker for Mercury Exposure and Toxicity
Also on the subject of testing, yes biochemical testing is confusing and in many cases handled improperly. However, in the last few years, Mt. Sinai has been DNA testing for certain forms of porphyria. According to the laboratory, they will test for AIP, HCP, VP, (they also have a combined test for the acute forms) as well as DNA tests for CEP, PCT and EPP.
Many patients assume that they need biochemical evidence before pursuing DNA testing, but from what I have read, this is not the case. So, even though the testing may be expensive, it may be worth doing DNA testing instead of regular biochemical tests.
In my own case, I was dxed long ago with porphyria and told it was AIP. However, through my own research I have realized how misunderstood porphyrins and porphyrias really are and that even though the symptoms that alerted my doctors to a possible porphyria are classic porphyria symptoms (kool-aid urine, severe abdominal pain, skin issues etc. AND I have excess porphyrins in my urine and feces), it now appears that mercury can do the same. I have even read of a dental assistant who's mercury toxicity was fatal. Her case documented VERY similar symptoms to my own illness such as the red urine, proteinuria and abdominal pain. However, there is no mention of her having any porphyrin tests so that also makes me wonder since porphyria was not ruled out first. Because I was definitely exposed to mercury while working (also as an assistant), it is not a far putt to the idea that this is the cause of my illnesses with porphyria specific symptoms. Here is the name of the article about the assistant: "Fatal Mercury Intoxication in a Dental Surgery Assistant" by T.A. Cook and Peter O. Yates. Believe it or not the date on it is December 16, 1969!
I have also noticed that there are different groups of people, all not aware of each other apparently, who excrete porphyrins but are classified in various ways. For example:
* One group is obviously the patients who truly suffer from a form of porphyria. (yet, they too are misdiagnosed repeatedly)
* The next group appears to be those who have been poisoned by something (whether it be lead, mercury, other toxic metals, agent orage, pesticides or whatever).
* The next group are the autism patients and their parents who's blogs I sometimes read and wonder what in the world is going on because these children are also excreting porphyrins. The theory is that the cause is from mercury in vaccines, but I truly wonder why a form of porphyria is not also being ruled out just to be sure?
* The next group is similiar to the second group of those who have been exposed to something. I seperate them into their own group because of the event itself that appears to have caused it. These individuals I just recently read about who live near the area in TN where the ash spill occured not long ago. A few individuals have tested postitive for porphyrins in their urine. Now, it may be obvious that an exposure occurred, but what is the signficance of all of this? It reminds me of the event in Turkey where thousands of people developed porphyria due to ingesting wheat or something that was tainted somehow with chemicals (this is very well documented, but I flatline on remembering the name of the chemical).
I could ask a thousand questions and still probably ask some more. I guess my point is that something is being overlooked about porphyrins. Mainly that there is no consensus about what the cause of thier elevations really are.
I have been babbling for awhile now so will say thanks for posting and hop off :)