New onset diabetes may present as vomiting and volume depletion. Hypernatremic dehydration may present with hyperglycemia, which may confuse the diagnosis. Urine studies are useful to grade severity of volume depletion. Urine tests also should be considered in the workup of gastroenteritis, urinary infection, diabetic ketoacidosis, or renal tubular acidosis. Newborn infants may have a falsely low specific gravity, as their kidneys may not yet be able to concentrate urine.
Ketonuria is typical of anorexia.
Large ketones may suggest diabetes. Abdominal films are not routinely needed. Consider obtaining flat plate and upright views of the abdomen when the clinical differential includes appendicitis, small bowel obstruction, peritonitis or renal calculi. Rotavirus antigen is routinely available in many laboratories. Patients with severe volume depletion who fail oral hydration require IV fluid therapy.