Diet-induced oxalate nephropathy from excessive nut and seed consumption

BMJ Case Rep. 2020 Nov 30;13(11):e237212. doi: 10.1136/bcr-2020-237212.

Abstract

Oxalate is a metabolite consumed in nuts, beans and leaves, and excreted in urine. Oxalosis can cause nephropathy. We describe a rare case of a high-oxalate diet intended for irritable bowel syndrome (IBS) treatment causing oxalate nephropathy. A 59-year-old woman with a history of controlled hypertension presented with creatinine 1.8 mg/dL, increased from baseline 1.3 mg/dL. She denied recent illness, urinary stones, medication adjustments, herbal supplements and non-steroidal anti-inflammatory drugs use. Diet included six tablespoons of chia seeds and five handfuls of almonds daily to manage IBS symptoms. Her electrolytes, urinalysis and renal ultrasound were unremarkable. Her 24-hour urine output revealed increased oxalate and low citrate. Renal biopsy showed glomerulosclerosis, fibrosis and calcium oxalate deposition. She switched to a low-oxalate diet, with improvement in laboratory markers. An earlier dietary history could have raised concern for oxalosis prior to renal biopsy. Providers should be trained to identify at-risk patients and provide appropriate dietary counselling.

Keywords: acute renal failure; diet; irritable bowel syndrome.

Publication types

  • Case Reports

MeSH terms

  • Calcium Oxalate / analysis*
  • Creatinine / blood
  • Diet / adverse effects*
  • Female
  • Glomerulonephritis / etiology*
  • Humans
  • Hyperoxaluria / etiology
  • Kidney / chemistry
  • Kidney / pathology*
  • Middle Aged
  • Nuts / adverse effects
  • Oxalates / adverse effects*
  • Oxalates / urine
  • Prunus dulcis / adverse effects*
  • Renal Insufficiency, Chronic / complications
  • Seeds / adverse effects*

Substances

  • Oxalates
  • Calcium Oxalate
  • Creatinine