A 68 year old woman presents with an obviously incarcerated umbilical hernia. She has gross abdominal distention, is clinically dehydrated, and repos persistent fecaloid vomiting for the past 3 days. Although tired, weak, and thirsty, she is awake and ale and her sensorium is not paicularly affected. Laboratory analysis reveals a serum sodium concentration of 118 mEq/L. Which of the following is the most likely physiologic explanation for the serum sodium?
She has acute water intoxication She has been vomiting and trapping hypeonic fluids in the bowel lumen She has vomited and sequestered sodium-containing fluids, and has retained endogenous and ingested water There must be a laboratory error, because such a serum sodium level would have produced coma