Women over 50 should use an isotonic bowel prep before a colonoscopy, according to Queensland doctors reporting the case of severe hyponatraemia secondary to a hypertonic bowel prep.

A 61-year-old iron-deficient woman was admitted to a rural hospital for bowel preparation prior to an upper endoscopy and colonoscopy.

She was admitted as a precaution because of dizziness, chest tightness and nausea during a previous attempt to take the prep two months earlier.

Once in hospital, she was given one sachet of hypertonic bowel preparation in 250ml water and a second sachet two hours later, with both doses well tolerated, the Roma Hospital doctors reported in BMJ Case Reports.