Rosh Emergency Medicine Practice Test

In a patient with a history of significant electrolyte abnormalities and severe dehydration, what additional finding may indicate an eating disorder?

1. Amenorrhea

2. Callused knuckles

3. Lanugo

4. Low thyroid-stimulating hormone

The correct answer is: Callused knuckles

The presence of callused knuckles in a patient with a history of significant electrolyte abnormalities and severe dehydration is often associated with behaviors typical of bulimia nervosa, specifically repeated incidents of self-induced vomiting. This physical sign, medically termed "Russell's sign," emerges from the frequent contact of the knuckles with the teeth during vomiting, leading to abrasion and callousing. Including this finding in the context of significant electrolyte imbalances and dehydration can help indicate potential purging behaviors, reinforcing the possibility of an eating disorder in this patient. While other signs or symptoms, such as amenorrhea or lanugo, may also suggest an eating disorder, callused knuckles directly point to the behavior associated with bulimia, making it a more specific finding. Low thyroid-stimulating hormone can occur in various conditions, including eating disorders, but it is not as directly indicative of specific behaviors as the callused knuckles are.