Interesting:
http://www.snopes.com/food/warnings/starfruit.asp

Star fruit contains a neurotoxin that affects the brain and nerves but which people with healthy kidneys are able to filter out; it therefore poses no danger to those whose kidneys function normally. However, those with renal problems lack protection from that neurotoxin and thus risk "star fruit intoxication," a condition that manifests with insomnia, hiccups, vomiting, numbness of limbs, decreased muscle power, twitching of
muscles, confusion, and convulsions, with the time between ingestion and onset of symptoms varying from thirty minutes to fourteen hours. Intractable hiccups are often the first symptom to present itself.

While the majority of those hospitalized for star fruit intoxication do recover, some deaths have been associated with this condition. Star fruit-exacerbated complications in kidney patients are rare, but they are potentially fatal, and thus this fruit is best avoided by those with kidney problems, including those on dialysis. Indeed, dialysis is the only treatment known to be effective in treating this illness, yet it must be both daily and intensive to have the desired effect, and continuous dialysis has been recommended for severe cases.

The National Kidney Foundation (NKF) advises in its Dietary Guidelines for Adults Starting on Hemodialysis: "Always AVOID star fruit (carambola)."