Doctors traced a man's kidney failure to an unusual cause - his habit of drinking almost four litres of iced tea each day.
They ruled out several potential causes before stumbling on a reason for the 56-year-old Arkansas man's kidney problems. He said he drank about 16 glasses of iced tea every day. Black tea has a chemical known to cause kidney stones or even kidney failure in excessive amounts.
"It was the only reasonable explanation," said Dr Umbar Ghaffar of the University of Arkansas for Medical Sciences in Little Rock. She and two other doctors describe the case in yesterday's New England Journal of Medicine.
The unidentified man went to the hospital last May with nausea, weakness, fatigue and body aches. Doctors determined his kidneys were badly clogged and inflamed by the food chemical called oxalate.
The man is on dialysis, perhaps for the rest of his life, Ghaffar said.
Besides black tea, oxalate is found in spinach, rhubarb, nuts, wheat bran and chocolate. In rare cases, too much oxalate can lead to kidney trouble, but often there's also a contributing intestinal problem. That didn't seem to be the case for the Arkansas man, and he had no family or personal history of kidney disease.