Which of the following tests can help in diagnosing factitious diarrhea?

Symptom diaries are a valuable tool in diagnosing factitious diarrhea as they allow for careful tracking of bowel habits, timing, and associated behaviors over a specified period. A patient with factitious diarrhea, which is characterized by intentionally produced symptoms, may have discrepancies between what they report and the diary findings, offering insight into the validity of their claims. These diaries can reveal patterns inconsistent with genuine gastrointestinal disorders, such as the frequency and timing of episodes relative to the patient’s daily activities.

In contrast, while an electrolyte panel may reveal imbalances due to dehydration or other health issues, it doesn't specifically diagnose factitious diarrhea. Stool testing for pathogens focuses on identifying infectious causes of diarrhea but does not address the psychological aspects of factitious disorders. Imaging studies can help rule out organic pathology but similarly do not provide evidence of factitious behavior. Hence, symptom diaries directly engage with the patient's reporting and can elucidate the inconsistencies characteristic of factitious disorders more effectively than the other testing methods.