A 19 year old man presents to your ED with vomiting and abdominal pain.

His blood results show:Na 134  (134-146 mmol/l)

K  4.8  (3.4-5.5 mmol/l)

Cl  100  (99-111 mmol/l)

HCO3  19  (22-26  mmol/l)

Urea  28.1  (3-8  mmol/l)

Creat  580  (<130  umol/l)

Describe and interpret the blood results

Give a reasonable differential and what simple test would aid your diagnosis?