MSRA-0517

MSRA-0517

A middle-aged patient presents with lethargy, weight loss and fainting episodes. In the Emergency Department, a postural drop in blood pressure is noted of > 20 mmHg systolic from the supine to the standing position. Blood glucose is 2.9 mmol/l, and Na+ is 122 mmol/l.
What is the cause of this patient’s condition?