He was then transferred to a local rehabilitation hospital and was found to have severe hypercalcaemia with a serum corrected calcium peak of 3.16 mmol/l (RR 2.10–2.60 mmol/l) (Fig. 1). At this stage he was consuming a regular diet and ambulating 50 m daily using a walking frame, and his renal function had been normal for the previous 4 weeks. There were no overt clinical signs of adrenal insufficiency. His medications included duloxetine, quetiapine, pregabalin, and methadone 20 mg in the morning and 15 mg in the evening for pain relief. Prior to the hospital admission he had not been taking any regular opioids, but had intermittently abused illicit drugs including heroin.