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