Background: Extreme anorexia nervosa (AN) is defined as a BMI < 15 kg/m 2 in those meeting DSM-V diagnostic criteria for AN. This study seeks to define the frequency of medical complications in this group of patients in order to help inform the care of individuals < 65% ideal body weight who seek treatment for their extreme eating disorders. Methods: Through retrospective chart review and computerized data collection, we obtained the baseline characteristics and medical findings of 281 adult patients, with AN restricting and binge-purge subtypes, admitted to the ACUTE unit for medical stabilization between May 2013 and August 2018. Results: In this population, with a mean admitting BMI of 12.1 kg/m 2 (range = 7.5-15.7), 56% admitted with bradycardia, 45% demonstrated increased liver function tests (LFTs) on admission, 64% admitted with leukopenia, 47% with anemia, and 20% presented with thrombocytopenia. During admission, 38% developed hypoglycemia, 35% developed refeeding hypophosphatemia, nearly 33% of patients developed edema, and low bone mineral density was diagnosed in almost 90% of the patients. Highly elevated LFTs (>3x upper limits of normal) predicted hypoglycemia, and low BMI predicted refeeding hypophosphatemia (p = .001). Conclusions: Although conclusions drawn from the findings presented in this descriptive study must be tempered by relevant clinical judgement, these findings showcase that patients with extreme AN are at significantly increased risk for many serious medical complications secondary to their state of malnutrition and also with initial refeeding.

Anorexia nervosa is a mental illness characterized by selfstarvation, marked weight loss, and malnutrition. As the illness worsens, numerous medical complications develop throughout the body. Some of these resolve with effective nutritional rehabilitation and weight gain, whereas others can lead to permanent damage. KEY POINTS The structural cardiac hallmark of this disease is myocardial atrophy characterized by a reduction in left ventricular mass index and volume, which commonly results in mitral valve prolapse. Most female patients are amenorrheic and have low estrogen levels because they have reverted to a prepubertal state; male patients have low testosterone levels. Marked loss of bone mineral density occurs, which can lead to early osteopenia and osteoporosis, even in adolescent patients, and this loss may be permanent. Pulmonary complications include spontaneous pneumothorax, pneumomediastinum, and aspiration pneumonia. Patients may also have generalized brain atrophy, damaged gray and white matter, and cognitive defi cits that persist after treatment.

People with anorexia nervosa (AN) tend to shy away from engaging in typical primary care provider relationships in order to avoid detection. Therefore, they may seek care for their medical concerns through a local emergency department (ED). Inherently, AN is associated with a litany of medical complications, which become more prevalent as the severity of their eating disorder increases. Notwithstanding the typical young age at the onset of AN, no body system is immune to these medical complications. Thus, ED providers may need to pursue a medical diagnosis in order to explain presenting symptoms in people with AN. In addition to the medical issues, AN is also a serious mental illness with high mortality rates, including deaths by suicide. Therefore, ED providers also need to be familiar with relevant mental health issues for these people.