wiki:metabolic:porphyria

Porphyrias

a set of genetic (AD,AR and X-linked versions) metabolic disorders, each a defect in one of the 8 enzymes in the heme biosynthetic pathway resulting in the accumulation of precursors of heme. Porphyrins are the major precursors.
can be classified as hepatic or erythropoietic based on whether the heme precursors 1st accumulate in the liver or the bone marrow and red blood cells
also classified as acute and chronic or cutaneous porphyrias

“classic triad” suggesting acute porphyria:

abdominal pain
central nervous system abnormalities
peripheral neuropathy

Hepatic	Erythropoietic	Acute	Chronic
• acute intermittent porphyria (AIP) • variegate porphyria (VP) • aminolevulinic acid dehydratase deficiency porphyria (ALAD) • hereditary coproporphyria (HCP) • porphyria cutanea tarda (PCT)	• Congenital erythropoietic porphyria • Erythropoietic porphyria • Hepatoerythropoietic porphyria • X-linked protoporphyria	• Acute intermittent porphyria • ALA dehydratase deficiency porphyria (Doss porphyria) • Hereditary coproporphyria • Variegate porphyria	• Congenital erythropoietic porphyria • Erythropoietic porphyria • Hepatoerythropoietic porphyria • Porphyria cutanea tarda • X-linked protoporphyria

Hepatic porphyrias

presentation:
- generally neurological
- neuropathic abdominal pain is most common presentation.
- seizures, psychosis
- back pain
- acute polyneuropathy.
- Occasionally some cutaneous manifestations.

Investigations:
- Urine porphobilinogen (PBG)
- Decreased erythrocyte porphobilinogen deaminase (PBGD) activity
- commonly - hyponatraemia and raised transaminases

Management:
- supportive - IV fluid, analgesia
- IV haem arginate (human hemin) - 3mg/kg (to a maximum of 250mg) once daily for 4 consecutive days.

References include:

Acute Hepatic Porphyria review
Emed porphyrias