Gross Anatomy: Tea Time in the ED
by Sarah Wickline Wallan
Staff Writer, MedPage Today
Last spring, a 54-year-old man in Arkansas presented to the emergency department with weakness, fatigue, and body aches. A urine sample revealed “remarkable” sediment with “abundant” calcium oxalate crystals but no blood, Fahd Syed, MD, of the Central Arkansas Veterans Healthcare System in Little Rock, and colleagues wrote in the New England Journal of Medicine.
Calcium oxalate crystals, a hallmark of kidney stones, or the consumption of antifreeze, led the physicians down several diagnostic paths.
But the patient hadn’t ever had a kidney stone and his kidney ultrasound was normal.
The patient had an elevated serum creatinine level of 4.5 mg/dL, a marked increase over the 2.5 mg/dL he had a year ago, and the 1.2 mg/dL he had 6 months before that.
The physicians decided to do a renal biopsy. Among the oxalate crystals, they found interstitial inflammation with eosinophils, and interstitial edema consistent with oxalate nephropathy.
The man’s urinary excretion levels of oxalate were more two to 14 times the norm at 99 mg in 24 hours. Despite the levels in the literature on the amount that Americans consume (152 to 511 mg per day), the Academy of Nutrition and Dietetics recommends no more than 50 mg per day.
This patient was in renal failure, and it was time for dialysis.
The docs asked about consumption of known sources of acute oxalate nephropathy: antifreeze, star fruit, juice fasts, things containing ascorbic acid, cucumber tree fruit, rhubarb, and peanuts.
The patient finally admitted to drinking 16 8-oz glasses of iced black tea per day. Black tea contains 50 to 100 mg per 100 ml of oxalate. The authors estimated the man’s consumption of oxalate exceeded 1,500 mg per day.
In the end, Syed’s team speculated that oxalate nephropathy, which may result from excessive consumption of iced tea, “may be an underrecognized cause of renal failure.”