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Kidney Week

Abstract: SA-PO089

Spilling the Tea ON AKI

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

  • Carroll, Gabrielle V., University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States
  • Primera, Gabriella, Baystate Medical Center, Springfield, Massachusetts, United States
  • Chen, Connie, Baystate Medical Center, Springfield, Massachusetts, United States
  • Patel, Parth, Baystate Medical Center, Springfield, Massachusetts, United States
  • Jobbins, Kathryn, Baystate Medical Center, Springfield, Massachusetts, United States
  • Landry, Daniel L., Baystate Medical Center, Springfield, Massachusetts, United States
Introduction

Oxalate nephropathy (ON) is characterized by oxalate crystal deposition in the tubulointerstitium leading to acute kidney injury (AKI) and possible chronic kidney disease (CKD).1 We present two cases of ON from excessive black tea consumption with full recovery.

Case Description

Case 1: A 52-year-old diabetic male was admitted after two weeks of poor solid food intake complicated by three days of acute left-sided vision loss and creatinine 8.5 mg/dl (baseline 1.6 mg/dl). Urinalysis showed benign sediment without proteinuria. Renal ultrasound revealed no hydronephrosis. MRI orbit showed bilateral increased optic nerve enhancement. Renal biopsy demonstrated acute tubular injury with calcium oxalate deposits and underlying diabetic nephropathy (DN). He later reported consumption of 5.5 liters of black tea a day for several weeks. He had full recovery of his renal function 2 months later after complete cessation of black tea intake. He never regained left eye vision, which was likely due to acute oxalate vasculopathy.

Case 2: A 70-year-old diabetic male was admitted for abnormal creatinine of 5.9 mg/dL (baseline 1.2 mg/dl) in the setting of one week of diarrhea. He denied toxic ingestion but had consumed large volumes of black tea for months to lose weight. He had a benign urinary sediment and enlarged kidneys on ultrasound (13 cm). Renal biopsy revealed DN changes with acute ON.2 Avoidance of black tea led to full renal recovery within 4 months.

Discussion

Hyperoxaluria is defined as a urine oxalate level greater than 40-45 mg/day.2 US diets contain approximately 150 mg/day of oxalate with intake over 1000 mg/day associated with toxicity.3 A recent 2020 study described 4.1% of biopsies in the New York City metro area containing oxalate deposits, contributing to CKD progression in 3.6% of cases.4

Causes of hyperoxaluria include primary hyperoxaluria type1 and 2, and secondary hyperoxaluria from nutritional deficiencies, increased intestinal absorption, impaired excretion, or excessive intake of oxalate-rich foods or precursors.2 Black tea contains 50-100 mg of oxalates per 100ml.5

Treatment of ON includes supportive care and calcium supplementation to bind intestinal oxalate. Over-ingestion of black tea is an underrecognized cause of acute ON. While acute ON can lead to residual CKD, our cases are notable for full renal recovery after timely cessation of the offending agent.