A 23-year-old woman comes to the emergency department due to right wrist pain after a fall. The patient fell onto her outstretched hand while walking across the floor at a gym where she exercises regularly. She has no significant medical history and takes no medications. The patient says she has tried several diets to lose weight and is currently consuming a vegan diet. Her last menstrual period was 3 months ago. She does not use tobacco, alcohol, or illicit drugs. Temperature is 36.1 C (97 F), blood pressure is 90/58 mm Hg, and pulse is 50/min. BMI is 18.3 kg/m². Weight is 50 kg (110.2 lb) and height is 165 cm (5 ft 5 in). Physical examination shows tenderness and swelling over the distal radius. The parotid glands are enlarged and there are fine, soft hairs on her extremities. Urine pregnancy test is negative. X-rays reveal a nondisplaced fracture of the right distal radius and generalized radiolucency of the bone. Which of the following is the most likely diagnosis?

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11ec160b_35fa_e94b_9249_01d5e3ce4ccf_MD0001_00 This patient has a fragility fracture (ie, fracture due to low-energy trauma) and radiolucency of bone on x-ray, suggesting osteoporosis. In light of her restricted diet, thin body habitus, and cessation of menses, this is likely due to a low-estrogen state and functional hypothalamic amenorrhea (excessive exercise or weight loss suppresses secretion of GnRH, leading to decreased release of FSH and low estrogen levels). She also has vital sign abnormalities (eg, bradycardia, low body temperature) and lanugo (ie, fine, downy body hair) that together raise suspicion for anorexia nervosa (AN). AN is characterized by restriction of energy intake below that needed to maintain normal body weight (BMI typically <18.5 kg/m²), leading to an emaciated body habitus and clinical features of starvation. Patients with AN have a distorted body image and an intense fear of gaining weight or becoming fat. Common behaviors include excessive caloric restriction, intensive exercise, and binge eating/purging (eg, self-induced vomiting, misuse of laxatives or diuretics). (Choice B) Avoidant/restrictive food intake disorder is characterized by inadequate food intake due to lack of interest in eating, dislike of the sensory experience of eating, or concerns about the consequences of eating without an associated disturbance in body image. This disorder typically presents in childhood or adolescence, and patients do not have signs of recurrent vomiting (eg, parotid hypertrophy, as in this patient). (Choice C) Bulimia nervosa is characterized by recurrent binge eating/purging and preoccupation with body image, much like in many patients with AN. However, patients with bulimia maintain their body weight at or above the minimally normal level and do not experience the signs of starvation that are present in this patient. (Choice D) Pellagra (ie, niacin deficiency) is characterized by dementia, dermatitis, and diarrhea. (Choice E) Vegan diets, which are free from animal products, can increase the risk for deficiencies of vitamin B₁₂, calcium, and vitamin D. Vitamin D deficiency may lead to low bone density and fragility fracture. However, rickets involves deficient mineralization and disruption of the growth plates and only occurs in children. (Choice F) Scurvy (ie, vitamin C deficiency) is characterized by skin and mucosal hemorrhages, intraarticular bleeding, gingival swelling, impaired wound healing, and weakened immune response to local infections. Vitamin C is readily found in plant products; a vegan diet would not predispose to scurvy. Educational objective: Anorexia nervosa is an eating disorder characterized by low body weight, intense fear of becoming fat, and distorted body image. Medical complications due to starvation in anorexia include bradycardia, hypotension, osteoporosis, and amenorrhea. __________ References: Bone health in anorexia nervosa. (http://www.ncbi.nlm.nih.gov/pubmed/21897220)

A 23-Year-Old Woman Comes to the Emergency Department Due to Right