Case report

A 76 year old woman was admitted with rectal bleeding. Her past medical history included hypertension—treated with nifedipine—and long standing use of tobacco. Physical examination was unremarkable.

Laboratory results were normal—haemoglobin 106 g/l, white cell count 7.2×10⁹/l, platelets 357×10⁹/l, sodium 132 mmol/l, potassium 4.3 mmol/l, urea 6.2 mmol/l, and creatinine 98 µmol/l.

She underwent flexible sigmoidoscopy after being given a sodium phosphate enema (Fleet Ready-to-use; De Witt) the night before (day 1). Colonoscopy was performed on day 4 after she took two sachets of oral sodium phosphate solution (Fleet Phospho-soda; De Witt). Histological findings were consistent with chronic active ulcerative colitis. She was discharged and prescribed mesalazine.

On day 6 she presented with acute renal failure (creatinine 541 µmol/l). She received intravenous fluids and mesalazine was replaced by prednisolone enemas. A renal consultation was obtained.

Urinalysis was unremarkable. She was normocalcaemic (2.4 mmol/l) but mildly hyperphosphataemic (1.54 mmol/l). Results of a screen for glomerulonephritis and renal tract ultrasonography were normal. Interstitial nephritis secondary to mesalazine was considered and she underwent renal biopsy.

Twenty seven glomeruli were …