Refeeding syndrome

Anorexia nervosa is restriction of energy intake driven by an intense fear of weight gain and a distorted body image, producing a body mass index below 18.5 kg/m2 with bradycardia, hypotension, hypothermia, amenorrhea, and osteoporosis. Diagnosis is clinical; management starts with medical stabilization and slow, monitored nutritional rehabilitation to avoid refeeding syndrome, followed by family therapy in adolescents, with olanzapine as adjunctive pharmacotherapy and bupropion avoided for its seizure risk.

Cachexia is a cytokine-driven metabolic wasting syndrome of ongoing skeletal muscle loss, with or without fat loss, that complicates cancer, heart failure, COPD, chronic kidney disease, and chronic infection and cannot be reversed by nutrition alone. Diagnosis rests on greater than 5% weight loss over 12 months in the setting of chronic illness plus supporting features such as reduced strength, anorexia, and elevated inflammatory markers, and management combines treatment of the underlying disease with multimodal nutrition, resistance exercise, and appetite stimulants.

Bariatric surgery is the most effective durable treatment for severe obesity, offered to patients with BMI 40 or greater, or BMI 35 or greater with an obesity-related comorbidity, after medically supervised weight-loss attempts have failed. Sleeve gastrectomy and Roux-en-Y gastric bypass are the dominant procedures, and outcomes hinge on catching early anastomotic or staple-line leak (tachycardia is the key sign) and on lifelong nutritional surveillance for iron, B12, folate, calcium, vitamin D, and thiamine deficiency.

Hypokalemia is a serum potassium level below 3.5 mEq/L, most often caused by gastrointestinal or renal potassium losses, and it produces weakness, ileus, and arrhythmia risk through altered membrane excitability. Diagnosis rests on the urine potassium-creatinine ratio to separate renal from extrarenal causes, and treatment is intravenous or oral potassium chloride, with concurrent magnesium repletion, dosed to severity and symptoms.

Hypomagnesemia is a serum magnesium level below 1.7 mg/dL, most often caused by gastrointestinal losses, proton pump inhibitors, or renal magnesium wasting from diuretics and other drugs. It causes concurrent hypokalemia and hypocalcemia and can potentiate cardiac arrhythmias, and treatment is intravenous magnesium sulfate for significant symptoms or slow-release oral repletion for milder deficiency.

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection, identified by an acute rise in SOFA score of 2 points or more in a patient with known or suspected infection. Survival depends on recognizing the pattern early and completing the hour-1 bundle: lactate, blood cultures before antibiotics, broad-spectrum antibiotics such as cefepime 2 g IV every 8 hours, and 30 mL/kg crystalloid for hypotension or a lactate of 4 mmol/L or higher.

Celiac disease is an immune-mediated small-intestinal enteropathy triggered by dietary gluten in genetically predisposed individuals, presenting with malabsorptive diarrhea, iron-deficiency anemia, or dermatitis herpetiformis. Diagnosis requires IgA tissue transglutaminase serology with a total IgA level while the patient still eats gluten, confirmed by duodenal biopsy showing villous atrophy, and the only treatment is a strict lifelong gluten-free diet.

Primary adrenal insufficiency (Addison disease) is destruction or dysfunction of the adrenal cortex, most often autoimmune, causing combined cortisol and aldosterone deficiency with hyperpigmentation, hyponatremia, and hyperkalemia. Lifelong glucocorticoid replacement with hydrocortisone plus mineralocorticoid replacement with fludrocortisone is required, with sick-day dose increases to prevent adrenal crisis.