A 59 year old man presents to your ED with epigastric pain and vomiting. He is tender in the epigastrium with good bowel sounds.

He has been losing weight recently and complains of some vague backache over the lower thoracic spine .

His blood results:

pH    7.54   (7.36-7.44)

pCO2   54  (35-45 mmHg)

HCO3  46  (22-26 mmol/l)

BE   19

Sodium  122  (137-145 mmol/l)

Potassium  2.0  (3.5-5 mmol/l)

Chloride  61  (99-111 mmol/l)

Creatinine  70  (<130 umol/l)

Glucose  5.5  (4-6 mmol/l)

Lactate  1.6  (<1.5 mmol/l)

1. Describe the abnormalities
2. Give a differential diagnosis
3. What clinical sign would point you to the cause of the vomiting?
4. What do you think may be the underlying cause?

Thanks to Matt for this case