Canadian Association for Porphyria

About Porphyria

Types of porphyria

For the most part, the various syndromes that are classified under the collective name of porphyria are differentiated from each other on the basis of a combination of clinical symptoms and abnormal biochemical findings in blood, urine, and stool. On the basis of our current understanding of molecular biology this classification is somewhat unsatisfactory and illogical.

One of the earliest classifications was based on whether the major activity of the defective enzyme system is associated with the liver (hepatic) or with the bone marrow (erythropoietic). Often however the same defective metabolic process takes place in both organs. The porphyrias can also be classified by identifying the specific tissues in which the abnormal porphyrin concentrations exert their major toxic effects such as in the skin where they are called cutaneous porphyrias or in the liver where they are called hepatic porphyrias. Other organs such as the nervous system are frequently affected. Frequently, the disease is classified as latent because the patient is asymptomatic until some other outside stimulus such as drugs or sunlight initiates the onset of symptoms in a person who has the genetic predisposition for this disease. In these cases the patient may not even be aware that they are suffering from porphyria until something happens to change the activity of the enzyme system and precipitate the symptoms of the disease.

The most useful and perhaps most popular classification system is grouping certain types of porphyria as acute, occurring suddenly onset of serious potentially life threatening symptoms, or as chronic with intermittent problems that develop gradually over months and persist for years.

Porphyrias Symptoms Red Blood Cell Urinary Stool

  Porphyrins Porphyrins Porphyrins

    & Precursors  
acute intermittant porphyria N none ALA, PBG none
variegate porphyria N, P none ALA, PBG coproporphyrin

    coproporphyrin protoporphyrin
herediatry coproporphyria N, P none ALA, PBG coproporphyrin

ALAD deficiency porphyria N protoporphyrin ALA none
erythropoietic porphyria P uroporphyrin uroporphyrin coproporphyrin

  coproporphyrin coproporphyrin  
erythropoietic protoporphyria P protoporphyrin none protoporphyrin
porphyria cutanea tarda P none uroporphyrin isocoproporphyrin
hepatoerythropoietic porphyria P protoporphyrin uroporphyrin isocoproporphyrin
N = neurological
P = photosensitizing

Source: This information originally appeared in a booklet written for the Canadian Porphyria Foundation: A Guide to Porphyria (1991) by Dr. Barry A. Tobe, MD, Ph.D, FRCP(C), Toronto, Ontario, Canada. The content has been updated by Dr. Brian M. Gilfix, MDCM, PhD, FRCPC, DABCC, FACB on 22/03/2015. 

Last Updated: 22/March/2015

Medical Disclaimer

Care has been taken to ensure that the information on this website is accurate at the time of publication. This information is, however, intended for general guidance only and is not meant to substitute consultation from a recognized health professional. The Canadian Association for Porphyria/Association Canadienne de Porphyrie disclaims for itself and for the author of this information, all responsibility for any mis-statements or for consequences of actions taken by any person while acting on information contained herein. Physicians and patients must make their own decisions about therapy according to the individual circumstances of each case.

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