Makindo Medical Notes

Related Subjects: |Acute Porphyrias |Variegate Porphyria |Acute Intermittent Porphyria (AIP) |Porphyria Cutanea Tarda (PCT) |Porphyria Testing

AIP is the most common type of acute porphyria. It is five times more common in females and presents between 15 and 30 years of age.

About

• Amoxicillin and opiates thought to be safe in porphyria
• The porphyria of King George

Aetiology

• Defects in production/activity of porphobilinogen (PBG) deaminase.
• Autosomal dominant disorder with reduced PBG

Precipitants

• Attacks precipitated by fasting e.g. for surgery, and by many drugs
• E.g. phenobarbitone, alcohol, sulphonylureas and oestrogens and OCP.

Clinical

• Central abdominal pain, nausea, bilious vomiting, constipation or diarrhoea.
• Hypertension and neuropathy are common
• Muscle weakness, cranial nerve abnormality and seizures
• Affects Peripheral, Autonomic or Central nervous system (CNS).

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

The 6 Ps of AIP

• Porphobilinogen deaminase ↓
• Pain in abdomen (attacks in 95%)
• Persevering face
• Pee discolouration (dark red) Wine glass
• Psychiatric symptoms
• Peripheral neuropathy
• Precipitated by drugs + alcohol, Pill

Investigations: All samples collected must be protected from light.

• U&E: Low Na during an acute attack
• Elevated levels of 8-ALA and PBG
• In severe cases the urine develops a port wine colour due to the high content of porphobilinogen, an auto-oxidation product of PBG. Urinary porphobilinogen excretion raised between attacks
• Collection Bottles:
  • Blood - Purple EDTA
  • Urine - White plain 20 ml universal,
  • Faeces - Blue Faecal 20 ml universal

Management

• See Acute Porphyria topic link above
• Contact National Acute Porphyria Service (NAPS)

References

• Best practice guidelines on clinical management of acute attacks of porphyria and their complications