Starfruit toxicity

Background

• Starfruit (Averrhoa carambola) is a fruit native to Southeast Asia, but is also grown in South America, the Caribbean, Africa, and the United States
• Can be consumed raw or as juice, jam, pickles, and in cooked dishes

Mechanism of Toxicity

• Toxicity caused by two compounds, oxalic acid and caramboxin
  • Oxalic acid, a vitamin C metabolite, can worsen renal function but does not cause neurotoxicity
  • Caramboxin, an amino acid neurotoxin, stimulates glutamate receptors, which leads to seizures

Clinical Features

• Symptoms of neurotoxicity may occur in patients with renal disease, even 1-2 fruits or small volumes of juice
  • Case reports of AKI in patients with previously normal renal function who consumed large amounts (over 10 fruits or greater than 1 L of juice)
• Persistent hiccups - most frequent symptom
• Confusion
• Agitation
• Muscle twitching
• Nausea
• Vomiting
• Seizures - associated with poor prognosis

Differential Diagnosis

Seizure

• Epileptic seizure
  • First-time seizure
  • Seizure with known seizure disorder
  • Status epilepticus
  • Temporal lobe epilepsy
  • Non-compliance with anti-epileptic medications
  • Hyponatremia
  • INH toxicity
• Non-epileptic seizure
  • Meningitis
  • Encephalitis
  • Brain abscess
  • Intracranial hemorrhage
  • Alcohol withdrawal
  • Benzodiazepine withdrawal
  • Barbiturate withdrawal
  • Baclofen withdrawal
  • Metabolic abnormalities: hyponatremia, hypernatremia, hypocalcemia, hypomagnesemia, hypoglycemia, hyperglycemia, hepatic failure, uremia
  • Eclampsia
  • Neurocysticercosis
  • Posterior reversible encephalopathy syndrome
  • Impact seizure (head trauma)
  • Acute hydrocephalus
  • Arteriovenous malformation
  • Seizure with VP shunt
  • Toxic ingestion (amphetamines, anticholinergics, cocaine, INH, organophosphates, TCA, salicylates, lithium, phenothiazines, bupropion, camphor, clozapine, cyclosporine, fluoroquinolones, imipenem, lead, lidocaine, metronidazole, synthetic cannabinoids, theophylline, Starfruit)
  • Psychogenic nonepileptic seizure (pseudoseizure)
• Intracranial mass
• Syncope
• Hyperventilation syndrome
• Migraine headache
• Movement disorders
• Narcolepsy/cataplexy
• Post-hypoxic myoclonus (Status myoclonicus)

Evaluation

• CBC
• Chemistry
• LFTs
• CSF studies
• Urine toxicology
• CT Head without contrast
• EKG

Management

• Mixed results with hemodialysis, with some studies reporting no improvement even with repeated hemodialysis
• Case reports of rapid improvement with charcoal hemoperfusion

Disposition

• If seizing, admit for monitoring and further workup
  • One study showed mortality as high as 75% in seizing patients, 0.03% in patients without seizures

See Also

• Toxicology (Main)
• Traditional chinese medicine toxicology