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Related Subjects: |Acute Porphyrias |Variegate Porphyria |Acute Intermittent Porphyria (AIP) |Porphyria Cutanea Tarda (PCT) |Porphyria Testing
Acute porphyrias are hereditary disorders of haem biosynthesis; they have a prevalence of about 1 in 75 000 of the population. BNF states that if no safe alternative, drug treatment for serious or life-threatening conditions should not be withheld from patients with acute porphyria.
Type of Porphyria | Details |
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Acute Intermittent Porphyria (AIP) | The most common acute porphyria, caused by a deficiency in the enzyme porphobilinogen deaminase (PBGD). It typically presents with abdominal pain, neuropsychiatric symptoms, and autonomic dysfunction. |
Hereditary Coproporphyria (HCP) | Caused by a deficiency in coproporphyrinogen oxidase, leading to an accumulation of coproporphyrins. Symptoms are similar to AIP but may also include skin sensitivity to sunlight. |
Variegate Porphyria (VP) | Caused by a deficiency in protoporphyrinogen oxidase. It presents with both acute neurovisceral attacks and photosensitivity, leading to blistering of the skin upon exposure to sunlight. |
ALAD Deficiency Porphyria (ADP) | A rare type of porphyria caused by a deficiency in delta-aminolevulinic acid dehydratase (ALAD). It primarily presents with neurovisceral symptoms during acute attacks. |
Diagnostic Test | Details |
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Urine Test for Porphobilinogen (PBG) | The most important initial test during an acute attack. Elevated levels of PBG in urine are indicative of acute porphyrias, particularly Acute Intermittent Porphyria (AIP). |
Urine Test for Delta-Aminolevulinic Acid (ALA) | Elevated levels of ALA in the urine are also common during an acute attack and support the diagnosis of acute porphyrias. |
Plasma or Serum Fluorescence | Plasma or serum shows a characteristic fluorescence under ultraviolet light in cases of Variegate Porphyria (VP) and Hereditary Coproporphyria (HCP). |
Stool Analysis for Porphyrins | Useful in diagnosing Variegate Porphyria (VP) and Hereditary Coproporphyria (HCP), as these porphyrias cause elevated levels of porphyrins in stool samples. |
Genetic Testing | Confirms the specific type of porphyria by identifying mutations in the genes responsible for the enzyme deficiencies in the heme biosynthesis pathway. |
Liver Function Tests (LFTs) | While not diagnostic of porphyria itself, LFTs can help assess liver involvement and monitor potential hepatic complications in porphyria patients. |
Measurement of Enzyme Activity | Measuring the activity of specific enzymes (e.g., PBG deaminase) can help diagnose certain types of porphyrias, such as AIP. |
BNF: Haem arginate is administered by short intravenous infusion as haem replacement in moderate, severe, or unremitting acute porphyria crises. In the United Kingdom the National Acute Porphyria Service (NAPS) provides clinical support and treatment with haem arginate from two centres (Cardiff and Vale University Health Board and King's College Hospital) (see Useful resources).
Drugs to avoid (check all): Diclofenac, Alcohol, OCP, HRT, TCA, Benzodiazepines, Anaesthetic agents (barbiturates, halothane), Antibiotics (cephalosporins, sulfonamides, macrolides, tetracyclines, rifampicin, trimethoprim, chloramphenicol, metronidazole), Metoclopramide, ACEI, CCB, Statins, Anticonvulsants, Furosemide, Sulfonylureas, Lidocaine, Gold salts, Antihistamines, Amphetamine