Final answer:
A nurse should suspect bulimia in an adolescent with calluses on the back of knuckles from self-induced vomiting. BMI less than 17 can indicate anorexia nervosa, and nail pitting and bradycardia are not specific to bulimia.
Step-by-step explanation:
To suspect that an adolescent has bulimia, which is an eating disorder characterized by the cycle of binge eating and purging, a nurse should look for specific physical signs. One sign that may lead a nurse to suspect bulimia is calluses on the back of knuckles, also known as Russell's sign.
This occurs from self-induced vomiting where an individual uses their fingers to trigger their gag reflex to purge, leading to repeated trauma to the knuckles. Other suspicious signs, but not listed in your options, may include dental enamel erosion, electrolyte imbalances, and psychological indications such as an intense fear of weight gain despite having a normal weight.
The other options, such as 'body mass index less than 17', 'nail pitting', and 'bradycardia' are more commonly associated with other conditions. A body mass index (BMI) less than 17 might indicate anorexia nervosa, which is another type of eating disorder characterized by a severe restriction of food intake leading to weight loss and a dangerously thin body frame. Nail pitting can be associated with psoriasis or other systemic diseases, and bradycardia can occur in various cardiovascular conditions or as a physiological response in athletes.