Serum chemistry (elevated anion gap)
VBG
Glucose (usually euglycemic or hypoglycemic)
Urinalysis (ketonuria)
Serum beta-hydroxybutyrate
Lactate
Salicylate level (if overdose suspected)
Serum osmolality (if toxic alcohol ingestion suspected)
Starvation ketoacidosis
Diabetic ketoacidosis
Alcoholic ketoacidosis
Diabetic ketoacidosis 
Lactic acidosis
Toxic alcohols 
Cerebral edema in DKA
Uremia