The pathogenesis of an increasing number of chronic diseases is being attributed to effects of the immune system. However, its role in the development and maintenance of anorexia nervosa is seemingly under-appreciated. Yet, in examining the available research on the immune system and genetic studies in anorexia nervosa, one becomes increasingly suspicious of the immune system’s potential role in the pathophysiology of anorexia nervosa. Specifically, research is suggestive of increased levels of various pro-inflammatory cytokines as well as the spontaneous production of tumor necrosis factor in anorexia nervosa; genetic studies further support a dysregulated immune system in this disorder. Potential contributors to this dysregulated immune system are discussed including increased oxidative stress, chronic physiological/psychological stress, changes in the intestinal microbiota, and an abnormal bone marrow microenvironment, all of which are present in anorexia nervosa.

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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.

Bulimia nervosa, a mental illness 4 times more common than anorexia nervosa, is characterized by binge-eating followed by compensatory purging behaviors, which include self-induced vomiting, diuretic abuse, laxative abuse, and misuse of insulin. Patients with bulimia nervosa are at risk of developing medical complications that affect all body systems, especially the renal and electrolyte systems. Behavior cessation can reverse some, but not all, medical complications. KEY POINTSMost people with bulimia nervosa are young and of normal weight, or even overweight, making detection and diagnosis diffi cult.As a consequence of purging behaviors, pseudo-Bartter syndrome can develop due to chronic dehydration, placing patients at risk for electrolyte abnormalities such as hypokalemia, as well as marked and rapid edema formation when purging is interrupted.Electrolyte and metabolic disturbances are the most common causes of morbidity and mortality in patients with bulimia nervosa. Hypokalemia should be managed aggressively to prevent electrocardiographic changes and arrhythmias such as torsades de pointes.Diabetic patients who purge calories through manipulation of their blood glucose are at high risk for hyperglycemia, ketoacidosis, and premature microvascular complications.Gastrointestinal complaints are common and include gastroesophageal refl ux disease.