A 5 year old boy is brought to the emergency room by EMS after having diarrhea for 5 days and feeling lethargic for the past 12 hours. He has an unremarkable past medical history. Immunizations are up to date.  Family history reveals that family members are well other than 2 siblings who have had diarrhea. Social history is non-contributory. Upon examination, the patient appears dehydrated. The patient is responsive but lethargic. The neurological,respiratory, and skin exams appears normal. The cardiovascular examination shows normal heart sounds and no murmurs. Eyes are sunken, mucous membranes are dry, pulses are palpable, capillary refill is 4 seconds centrally. The abdominal examination reveals diffuse but non-peritonitic tenderness.