Porphyria: theories of etiology and treatment

Hepatic porphyrias

The porphyrias are metabolic disorders characterized by abnormal heme biosynthesis with excessive accumulation and excretion of porphyrias or porphyrin precursors. Defects in the enzymes of the heme biosynthetic pathway result in porphyria. Several of the disorders have been classified as hepatic because the major site of the biochemical defect has been localized to the liver. This article describes the enzymes of the heme biosynthetic pathway, the clinical features of the hepatic porphyrias and management of the disorders.

Porphyrin enzyme analysis in an oral pathology practice: a look back over four years

The porphyrias are defined by specific enzymes having diminished activity. More enzymes have become available for routine testing. Measurement of urine and stool porphyrin and porphyrin precursor elevations are important, but in many instances are not found or found in confusing patterns. The use of enzyme analysis can often be helpful in identifying those patients with a genetically diminished enzyme activity level. Looking back over the last four years, modifications in evaluating patients for porphyria were developed and are related in this article. In 91 patients, patterns of enzyme deficiencies were seen that have been observed by others; however, new observations have been made. While many of the enzymes in the porphyrin pathway are available for testing, others need to come on line as soon as possible, particularly protoporphyrinogen oxidase.

Fatigue syndromes: new thoughts and reinterpretation of previous data

Recently, the author has identified 19 patients who have complained of marked fatigue that had abnormal responses to copper test bracelets or necklaces. At this time, 8 have been shown to have at least one enzyme deficiency in the heme pathway. These patients have been diagnosed with multiple sclerosis, chronic fatigue syndrome and other non-specific diagnoses. A lengthy but still limited review of the literature was performed regarding the following conditions: multiple sclerosis (MS), hepatic porphyria (HP), chronic fatigue syndrome (CFS) and paralytic polio (PP). The text will focus on similar epidemiologies, laboratory findings and clinical courses. Copper as a common but not unique etiologic agent will be discussed; as will the heme pathway, a biologic process that may be disordered in all.

Excretion of porphyrins and porphyrin precursors during neuromuscular paralysis produced by dithiobiuret

Urinary excretion of porphyrin precursors delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) and total porphyrins was measured during intoxication of rats with 2,4-dithiobiuret (DTB), a chemical which produces delayed-onset neuromuscular weakness, in an attempt to ascertain whether or not DTB poisoning in the rat would serve as an animal model of the neurologic symptoms of acute intermittent porphyria. Daily administration of DTB (1 mg/kg/day, i.p.) produced flaccid skeletal muscle weakness first detected after 4 to 5 days of treatment. Onset of skeletal muscle weakness was associated with a significant increase in urinary excretion of ALA. The excretion of PBG and total porphyrin was also increased; however, the increase was not significant. The increase in porphyrins and porphyrin precursors was due to increased urine output which coincided with the onset of neuromuscular weakness; urinary concentrations of ALA, PBG, and porphyrins were not increased by DTB. Measurements of free-erythrocyte protoporphyrin, taken after 7 days of DTB treatment, indicated a significant elevation of free erythrocyte protoporphyrin concentration. The pattern of alterations in the heme precursors associated with DTB-induced paralysis in rats is quite different from that observed in humans afflicted with acute intermittent porphyria. Therefore, we conclude that DTB-induced paralysis in the rat does not represent an accurate animal model of acute intermittent porphyria.