Starfruit toxicity

Background
Vertical, end view, and cross section of the ripe carambola "starfuit".
  • 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
  • In traditional Chinese medicine, used to treat diabetes mellitus[1]

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[1]
  • Raw fruit has high potassium content while juice does not[2], however hyperkalemia not found in many patients[3][4]

Clinical Features
  • Wide range of non-specific symptoms[1][2][3][4][5][6][7]
    • Persistent hiccups - most frequent symptom
    • Confusion
    • Agitation
    • Muscle twitching
    • Nausea
    • Vomiting
    • Seizures - associated with poor prognosis[3][8]
  • Symptoms of neurotoxicity may occur in patients with renal disease, even 1-2 fruits or small volumes of juice[5]
    • 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)[5][6][7]

Differential Diagnosis

Seizure

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[2][5]
  • Case reports of rapid improvement with charcoal hemoperfusion[4][9][10][11]

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[3]

See Also

References
  1. Garcia-Cairasco N. et al. Elucidating the neurotoxicity of the star fruit. Angewandte Chemie (International ed. in English). 2013;52(49):13067-70.
  2. Chang J. et al. Fatal outcome after ingestion of star fruit (Averrhoa carambola) in uremic patients. American journal of kidney diseases : the official journal of the National Kidney Foundation. 2000;35(2):189-93.
  3. Tsai M. et al. Status epilepticus induced by star fruit intoxication in patients with chronic renal disease. Seizure. 2005;14(7):521-5.
  4. Wu M. et al. Hemoperfusion as an effective alternative therapy for star fruit intoxication: A report of 2 cases. American journal of kidney diseases : the official journal of the National Kidney Foundation. 2006;49(1).
  5. Oliveira de. et al. Why eating star fruit is prohibited for patients with chronic kidney disease? Jornal brasileiro de nefrologia : 'orgao oficial de Sociedades Brasileira e Latino-Americana de Nefrologia. 2015;37(2):241-7.
  6. Abeysekera R. et al. Star fruit toxicity: A cause of both acute kidney injury and chronic kidney disease: A report of two cases. BMC research notes. 2015;8.
  7. Neto MM. et al. Star fruit: Simultaneous neurotoxic and nephrotoxic effects in people with previously normal renal function. 2009;2(6).
  8. Neto M. et al. Intoxication by star fruit (Averrhoa carambola) in 32 uraemic patients: Treatment and outcome. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2002;18(1):120-5.
  9. Chen L. et al. Chronic renal disease patients with severe star fruit poisoning: Hemoperfusion may be an effective alternative therapy. Clinical toxicology (Philadelphia, Pa.). 2005;43(3):197-9.
  10. Chan C. et al. Star fruit intoxication successfully treated by charcoal haemoperfusion and intensive haemofiltration. Hong Kong medical journal = Xianggang yi xue za zhi. 2009;15(2):149-52.
  11. Wu C. et al. Sustained low-efficiency daily diafiltration with hemoperfusion as a therapy for severe star fruit intoxication: A report of two cases. Renal failure. 2001;33(8):837-41.
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