It's an interesting idea, but I'm not sure I agree 100%, though I could be more convinced.

A quick search of Wikipedia turns up no fewer than nine different types of porphyria classified by the organs they primarily affect.

Out of those nine, Henry cannot have possibly had 7 of those types.  One of those types is found only in infants who receive UV light treatment for jaundice.  Five of the remaining six are characterized by photosensitivity.  Three of those include photosensitivity so severe the patient exhibits skin lesions or blisters of some sort.  Henry was very athletic in his youth and known to be outdoors frequently hunting or something of the sort.  Someone would have noticed blisters and commented on it–probably not to Henry, but to someone else.  One of the remaining three with photosensitivity also includes developmental delay as a symptom and Henry was clearly not developmentally delayed.  Even without all that, of all the complications and issues involved in Henry's health, I don't think I've ever heard of anyone mentioning even simple photosensitivity and it seems like people with porphyria have pretty severe photosensitivity.  So, we're down to two remaining possible types of porphyria:  one of these is an X-linked porphyria which, in and of itself doesn't disqualify it as a contender.  But it is an erythopoietic porphyria, and it doesn't seem that symptoms of any of the erythropoietic porphyrias include neurological or psychiatric symptoms.

So, the only porphyria remaining on the list is acute intermittent porphyria which IS a possibility.  I don't know much about the chief physical complaints Henry had in the late years of his life and most of the symptoms (except for the purple urine and the psychotic episodes) are pretty typical of many older people.  My chief hang-up with this one is that it is autosomal dominant.  Unless Henry had a spontaneous genetic mutation (which is ENTIRELY possible!), one of his parents would have also had to have the condition.  Maybe someone who knows more about Henry VII can convince me because I honestly know very little about H8's parents.

Lorraine said:

His mother was known to suffer from Porphyria, Elizabeth of York, and it also straddled over the family line with Mary Queen of Scots having the condition as well.

It could also explain the massive loss of babies through miscarriages and dying in the first few weeks of their lives, if the genetic mutation was quite bad.  Henry blames his wives, for their failure, also his son the young King Edward VI died aged 16 years was known to be a sickly child all of his life.

If Elizabeth suffered from porhyria, then Mary could have inherited it from her grandmother Margaret Tudor.

However Edward showed very few signs of ill-health until his last year.

Ok, quickly before my kids realize the computer is open:

I can't find any information on Elizabeth of York having porphyria and AIP is usually really severe in women because of female hormone interference.  But it could be I'm looking in the wrong places.

It seems that no one knows what “triggers” AIP in some people and not in others who carry the gene.  However, we know that Henry's diet was not the healthiest and we know that he liked to be his own apothecary so it's possible that something he was self-medicating with triggered the condition in him.

I know nothing about this disease, but I just finished reading John Guys book, “My Heart Is My Own, about Mary Queen of Scots.  There were claims that George III may have suffered from porphyria.  Medical historians tried tracing the disease through the Stuart line to James I.  But many claimed he did not suffer from porphyria, but that he was manic depressive. Guy also states that even if James had the disease, it could have come from his father's side.  As for Mary and the illnesses she suffered in her youth, there is significant evidence they were unrelated to porphyria.