Psychiatryniche
A 26-year-old woman with a two-year eating disorder is admitted with cramps and profound weakness. She weighs 58 kg and has not lost weight. She denies vomiting and denies taking any medication, and her bowels open once daily and are formed. Investigations: sodium 138 mmol/L (135-145), potassium 2.7 mmol/L (3.5-5.2), chloride 88 mmol/L (95-110), bicarbonate 35 mmol/L (22-32), pH 7.50 (7.35-7.45), and spot urinary chloride 8 mmol/L. Which one of the following behaviours best explains this biochemical pattern?