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 It's being called iced-tea nephropathy by the New England Journal of
Medicine, which published a letter describing the case.
The source of the problem was an excessive amount of oxalate, a
compound found in many foods. Excessive amounts can also come from
"juicing," having gastric bypass surgery, and by consuming foods
with a lot of ascorbic acid such as beets, spinach, nuts and
strawberries.
But in this case, the man reported that he was drinking 16
nine-ounce glasses of iced tea each day, giving him more than 1,500
milligrams of oxalate per day.
The Academy of Nutrition and Dietetics advises consuming no more
than 40-50 mg of oxalate per day, the authors note.
"If you drink tea once or twice a day, it probably wouldn't exceed
what is the normal range for Americans. But this patient was taking
10 times that amount," said Dr. Umbar Ghaffa of the University of
Arkansas for Medical Sciences in Little Rock, a coauthor of the
letter.
Consuming too much oxalate can lead to kidney stones, which can
damage the kidney by blocking the flow of urine. "But in this case
there were oxalate crystals inside the kidney, and that generates an
inflammatory reaction," Ghaffar told Reuters Health. "If that's not
resolved it will cause scarring and loss of the kidney tissue. So
that's what probably was happening in this patient."
He ultimately needed dialysis and remained on it because his kidney
damage was so extensive.
"Usually if they're at the stage where they need dialysis, it would
be unusual for it to reverse," said Dr. Gary Curhan, a professor of
medicine at Harvard Medical School who was not involved with the
case.
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The irony is that previous research has suggested that "people who
take tea in the usual amounts actually have a lower risk of kidney
stones,” Curhan said.
“But in this case, the person was drinking huge amounts of oxalate,"
he said. "I would caution people against drinking that much, but
drinking a glass or two would not concern me."
Ghaffar and her colleagues speculated that such regular excessive
consumption of oxalate "may be an underrecognized cause of renal
failure."
"The summer season is coming and a lot of people use a lot of iced
tea in this season," she said. "We just want to make patients aware
that too much of anything is bad."
SOURCE: http://bit.ly/1F7ZPXm
New England Journal of Medicine, online April 1, 2015.
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