A 23 year old college student is brought in after being found unconscious in his bedroom. He had been absent from lectures for the last 2 days. Further information is unavailable, as he lives alone.

His friends relate that he was 'distant' and 'withdrawn' during the last few weeks. He was in good health earlier, and a perusal of his medical records reveals nothing untoward. There is no history of recreational drug abuse, and he apparently consumed alcohol only infrequently.

A random capillary glucose, complete blood count, and serum electrolyte assay are within normal parameters. However, his renal profile is significant for a creatinine of 6.8 mg/dL (normal: < 1.5), and urea of 200 mg/dL (normal: <50).