A rare autosomal dominant inherited disorder characterised by a partial deficiency of porphobilinogen deaminase, which leads to the accumulation of porphyrin precursors in the body.
Most patients remain asymptomatic, but symptoms can be triggered by use of certain drugs or alteration of nutritional status.
The most common presenting features include pain in the abdomen, extremities, back, and chest; tachycardia; hypertension; nausea and vomiting; constipation; and peripheral motor neuropathy.
The pain is neuropathic and is not accompanied by inflammation.
Red or brownish urine results from marked increases in urinary excretion of haem pathway intermediates. Porphyrins are reddish and fluoresce when exposed to long-wave ultraviolet light. Porphobilinogen is colourless but degrades on standing to form brownish pigments.
Acute intermittent porphyria (AIP) is a rare genetic disorder characterised by a partial deficiency of porphobilinogen deaminase (PBGD), also known as hydroxymethylbilane synthase, the third enzyme in the haem biosynthetic pathway. As a result, the porphyrin precursors, porphobilinogen (PBG), and delta-aminolevulinic acid (ALA) accumulate in the body. Urinary excretion of ALA, PBG, and porphyrins is increased. Most patients remain asymptomatic with little or no elevation in ALA, PBG, and porphyrins, but the condition can be activated after puberty by some drugs and corticosteroid hormones or by reducing dietary intake.
History and exam
- delta-aminolevulinic acid (ALA)
- plasma total porphyrins
- urinary porphyrins using high-performance liquid chromatography (HPLC)
- faecal total porphyrins
- faecal porphyrins using high-performance liquid chromatography (HPLC)
- erythrocyte porphobilinogen deaminase (PBGD) activity
- porphobilinogen deaminase (PBGD) gene sequencing
- serum sodium levels
- MRI brain
Gagan Sood, MD
Department of Medicine and Surgery
Baylor College of Medicine
GS is an author of a number of references cited in this topic.
Karl E. Anderson, MD
Departments of Preventive Medicine and Community Health and Internal Medicine
University of Texas Medical Branch
KEA has received grants from the National Institutes of Health, the US Food and Drug Administration, and Alnylam Pharmaceuticals; he is an author of a number of references cited in this topic.
Alexios Carayannopoulos, MD
Interventional Spine Physiatrist
Pain Medicine Specialist
AC declares that he has no competing interests.
Kenneth E.L. McColl, MD, FRCP
Professor of Medical Sciences
KELM declares that he has no competing interests.
Neville Pimstone, MD
Professor Emeritus of Medicine
Division of Gastroenterology
UC Davis Medical Group GI Unit
NP declares that he has no competing interests.
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