“Food poisoning” is the part of the statement which the nurse identifies as the etiology.
Step-by-step explanation:
The causation or main cause or origin of a disease or an abnormal condition is referred etiology of the disease or condition. It denotes the root cause of the problem.
Etiology leads to signs and symptoms which depicts the diseased condition, which needs to be diagnosed and treated.
In the above case, the main cause or etiology for the diagnosis of fluid volume loss due to gastrointestinal upset is food poisoning. This has led to vomiting and diarrhea leading to fluid volume loss, low skin turgor, and weight loss in the patient.