Comprehensive Study Guide on Eating Disorders: Anorexia Nervosa, Bulimia Nervosa, Enteral Nutrition, and Refeeding Syndrome

Overview and Definitions of Eating Disorders

• General Eating Disorder Definition: A secondary mental health condition characterized by persistent disturbances in eating behaviors that result in significant physical or psychological impairment.
• Anorexia vs. Anorexia Nervosa:
  • Anorexia: A general medical symptom defined as a loss of appetite or inability to eat secondary to a chronic physical medical condition (e.g., chronic obstructive pulmonary disease [COPD], cirrhosis).
  • Anorexia Nervosa: A specific psychiatric eating disorder characterized by self-induced starvation and an intense, irrational fear of weight gain.
• Epidemiology and High-Risk Populations:
  • Primarily affects young teenagers and young adults.
  • Females demonstrate a statistically higher prevalence than males.
  • Males remain susceptible, particularly those competing in sports requiring strict weight categories (e.g., wrestling, boxing) or working in aesthetic-focused professions (e.g., modeling).

Anorexia Nervosa: Pathophysiology and Clinical Manifestations

• Core Psychopathology:
  • Characterized by a self-induced state of starvation driven by a severe, morbid fear of becoming overweight or fat, despite being clinically emaciated.
  • Associated with Body Dysmorphic Disorder (classified as a subtype of obsessive-compulsive disorder [OCD]), in which clients hyper-focus on perceived physical flaws.
  • Marked by a grossly distorted self-image: clients view themselves as obese with an elevated Body Mass Index ($\text{BMI}$), whereas objective physical evaluation reveals severe malnourishment ("skin and bones").
  • The cognitive distortion prevents clients from accepting objective reality, making treatment exceptionally challenging.
  • Serves as a maladaptive coping mechanism to gain a sense of control over life circumstances, particularly in adolescent females (cases have been observed in children as young as $9\,\text{years old}$).
• Behavioral Features:
  • Preoccupation with food: clients may invest significant energy into planning, handling, or preparing elaborate meals for others while consuming nothing themselves to project a facade of normal eating habits.
• Systemic Signs and Symptoms:
  • Weight and Body Habitus: Emaciation, severely low $\text{BMI}$, marked cachexia, and muscle atrophy.
  • Vital Signs: Severe hypotension and bradycardia due to profound intravascular hypovolemia and metabolic slowing.
  • Reproductive: Amenorrhea (cessation of menstrual cycles).
  • Integumentary:
    • Severe dry skin.
    • Alopecia (hair loss) and brittle fingernails.
    • Lanugo: Fine, downy hair growth across the body (physiologically identical to that seen in premature neonates), developed as a compensatory mechanism for thermoregulation due to loss of insulating subcutaneous adipose tissue.
    • Yellowing of the skin (carotenoderma/jaundice appearance) caused by the hepatic breakdown of endogenous cellular fats and bile secretion during starvation, exacerbated by concurrent anemia.
  • Oral Cavity: Stomatitis resulting from vitamin and micronutrient deficiencies.
  • Fluid Balance and Edema: Peripheral edema caused by severe hypoalbuminemia (inadequate protein intake causes reduced oncotic pressure, leading to fluid shifting into interstitial spaces rather than true intravascular volume overload).
  • Hematologic: Anemia secondary to iron and nutritional deficiencies, resulting in decreased hemoglobin ($\text{Hgb}$), hematocrit ($\text{Hct}$), and red blood cell ($\text{RBC}$) production.
  • Cardiovascular: Cardiac dysrhythmias secondary to profound electrolyte shifts, particularly hypokalemia (low potassium) and hypomagnesemia (low magnesium), which directly impair myocardial electrical conduction.

Bulimia Nervosa: Characteristics and Clinical Manifestations

• Binge-Purge Cycle:
  • Characterized by episodic, uncontrolled ingestion of abnormally large quantities of food (ranging from $2{,}000\,\text{to }3{,}000\,\text{calories}$ per episode) over a condensed timeframe.
  • Followed by compensatory purging behaviors designed to prevent weight gain.
  • In between binge-purge episodes, clients strictly restrict their caloric intake.
  • Behaviors are carried out in secrecy due to intense feelings of shame, guilt, and depression.
  • Driven primarily by a desire to conform to societal aesthetic expectations without pursuing the extreme emaciation characteristic of anorexia nervosa.
• Compensatory / Purging Mechanisms:
  • Self-induced vomiting:
    • Gastric acid erosion leading to deterioration of tooth enamel (often identified first during routine dental examinations).
    • Calluses or abrasions on the back of the hand and knuckles (Russell sign) from repeated manual induction of the gag reflex.
    • Excessive salivation (a protective bodily reflex shielding oral mucosa from caustic gastric acid).
    • Oral stomatitis, pharyngeal irritation, and mucosal ulcers or erosions of the esophagus and gastric lining.
  • Laxative and Enema Abuse: Frequent use of over-the-counter osmotic laxatives (e.g., MiraLAX) or enemas, causing severe perianal excoriation, skin breakdown, and chronic diarrhea.
  • Diuretic Abuse: Misuse of prescription diuretics or unregulated commercial dietary herbal supplements to induce rapid fluid loss.
  • Excessive Exercise: Compulsive physical training lasting hours on end.
• Clinical Presentation:
  • Clients typically present with a normal or slightly elevated $\text{BMI}$.
  • Onset is commonly observed in late adolescence or early adulthood.
  • Prognosis is generally more favorable than that of anorexia nervosa due to intermittent nutritional absorption, though psychological distress remains severe.
  • Fluid and electrolyte complications include rebound fluid retention/edema (especially following cessation of chronic diuretic abuse) and cardiac dysrhythmias caused by potassium depletion via vomiting and diarrhea.

Comparative Analysis: Anorexia Nervosa vs. Bulimia Nervosa

• Body Weight and BMI:
  • Anorexia Nervosa: Markedly subnormal $\text{BMI}$; emaciated state.
  • Bulimia Nervosa: Typically normal to slightly elevated $\text{BMI}$; outward physical appearance often conceals the disorder.
• Cognitive Perception:
  • Anorexia Nervosa: Profound, delusional body dysmorphia; an emaciated individual perceives their reflection as obese.
  • Bulimia Nervosa: Retains realistic perception of physical dimensions; motivated by fear of gaining weight and adherence to perceived social standards rather than complete visual disconnect.
• Unique Physical Signs:
  • Exclusive/Specific to Anorexia Nervosa: Lanugo, severe generalized cachexia, amenorrhea, marked hypoalbuminemic third-spacing edema.
  • Exclusive/Specific to Bulimia Nervosa: Severe dental enamel erosion, dorsal hand calluses, perianal irritation from chronic laxative abuse, esophageal mucosal ulcerations.
  • Overlapping Features: Depletion of essential electrolytes (hypokalemia, hypomagnesemia), cardiac dysrhythmias, dry skin, muscle weakness, stomatitis, and anemia.

Clinical Assessment and Screening Tools

• The SCOFF Questionnaire: A rapid, five-question screening tool used to identify potential eating disorders (an affirmative response to $\ge 2$ questions indicates a high likelihood of an eating disorder):
  • S (Sick): Do you make yourself Sick (induce vomiting) because you feel uncomfortably full?
  • C (Control): Do you worry you have lost Control over how much you eat?
  • O (One stone): Have you recently lost more than One stone ($1\,\text{stone} \approx 14\text{--}15\,\text{pounds}$) in a $3\,\text{month}$ period?
  • F (Fat): Do you believe yourself to be Fat when others say you are too thin?
  • F (Food): Would you say that Food dominates your life?
• Comprehensive Health History:
  • Screening for familial history of eating or psychiatric disorders.
  • Evaluation of socioeconomic background to differentiate psychiatric food restriction from financial food insecurity.
  • Occupational and athletic history assessment (e.g., modeling, dance, competitive wrestling).
  • Psychosocial assessment: screening for comorbid depression, low self-esteem, isolation, and shame surrounding purging behaviors.

Laboratory and Diagnostic Evaluations

• Laboratory Tests:
  • Complete Blood Count ($\text{CBC}$): Decreased hemoglobin ($\text{Hgb}$) and hematocrit ($\text{Hct}$) reflecting iron deficiency anemia.
  • Comprehensive Metabolic Panel ($\text{CMP}$):
    • Hypokalemia (potassium loss via emesis, laxatives, and malnutrition).
    • Hypomagnesemia and hypocalcemia.
    • Hypoalbuminemia (secondary to protein starvation).
    • Elevated serum creatinine secondary to pre-renal acute kidney injury from severe dehydration and diuretic abuse.
  • Iron Studies: Elevated transferrin levels (serum transferrin increases compensatorily when circulating iron stores are depleted, leaving unbound transport capacity).
• Diagnostic Investigations:
  • 12-Lead Electrocardiogram ($\text{EKG}$): Indicated immediately due to high risk of life-threatening cardiac dysrhythmias from hypokalemia and hypomagnesemia.
  • Dual-Energy X-ray Absorptiometry ($\text{DEXA}$ scan): Bone mineral density evaluation to evaluate for osteopenia or osteoporosis resulting from prolonged calcium and vitamin D deficiencies.

Interdisciplinary Treatment and Psychosocial Interventions

• Psychotherapy Modalities:
  • Cognitive Behavioral Therapy ($\text{CBT}$): Identifies and restructures cognitive distortions (e.g., catastrophizing, personalization, overgeneralization) regarding body weight, shape, and eating habits.
  • Family-Based Therapy ($\text{FBT}$): Essential for children and adolescents; engages parents and family support systems in nutritional re-establishment and structured home meal management.
  • Structured Milieu Therapy: Uses a controlled psychiatric inpatient or residential environment to model adaptive daily living, establish boundaries, and teach healthy community socialization.
• Therapeutic Nursing Communication:
  • Utilize nonjudgmental, open-ended communication.
  • Support patient autonomy and promote self-esteem by actively involving the client in the care plan, counteracting their underlying fear of losing control.
  • Establish realistic, measurable goals (e.g., SMART goals: preventing further weight loss rather than expecting rapid weekly weight gain of $15\text{--}20\,\text{pounds}$; working toward consuming $50\%$ of provided meal trays).
• Nursing and Mealtime Management:
  • Obtain scheduled weights, track vital signs, and maintain calorie counts (calculating meal percentages).
  • Post-meal observation: Clients with bulimia nervosa must be closely monitored during all meals and for at least $1\,\text{hour}$ postprandially to prevent surreptitious purging.
  • Supervise and set strict boundaries on physical exercise to prevent compulsive over-exercise in inpatient settings.
  • Collaborate with clinical dietitians to individualize nutrition plans; start with frequent, small feedings (e.g., $6\,\text{small meals daily}$) and progress upward slowly.
  • Provide texture-modified diets (e.g., pureed diet) when severe oral stomatitis or tooth erosion precludes regular chewing.

Pharmacological Therapies

• Role of Pharmacotherapy: Medications do not cure eating disorders directly; they serve as adjuncts to manage comorbid psychiatric conditions and physiological appetite issues.
• Antidepressants / Craving Reducers:
  • Selective Serotonin Reuptake Inhibitors ($\text{SSRIs}$): Commonly used for underlying depression and anxiety.
  • Serotonin-Norepinephrine Reuptake Inhibitors ($\text{SNRIs}$): Venlafaxine (Effexor) can be utilized to help suppress intense carbohydrate cravings.
  • Aminoketones: Bupropion (Wellbutrin) is noted for reducing binge-eating cravings.
  • Soloxac: Referenced in clinical discussions as an antidepressant intervention.
  • Client Education: Antidepressants require several weeks to produce therapeutic effects; recovery is prolonged (months to years), and relapses are common during periods of high acute stress (analogous to alcohol addiction recovery).
• Appetite Stimulants:
  • Dronabinol (Marinol): Synthetic cannabinoid formulated to stimulate appetite in severe anorexic states.
  • Megestrol: Synthetic progestin hormone agent utilized to enhance appetite and promote weight gain (frequently utilized in oncology settings for cancer cachexia, applied off-label in severe anorexia).

Enteral Nutrition and Tube Feeding Complications

• Total Enteral Nutrition ($\text{TEN}$):
  • Indicated when clients cannot tolerate oral intake ($\text{PO}$) due to physical erosion, swallowing dysfunction, or severe psychological refusal.
  • Delivered via Nasogastric ($\text{NG}$) tube (preferred for short-term nutritional rehab) or Percutaneous Endoscopic Gastrostomy ($\text{PEG}$) tube (reserved for long-term/permanent feeding access).
  • Administered via continuous infusion or intermittent bolus feedings.
• Complications and Nursing Actions:
  • Tube Obstruction/Clogging: The most frequent mechanical complication. Prevented and managed via routine scheduled water flushes and standardized institutional unclogging protocols.
  • Tube Dislodgement / Misplacement:
    • Immediate Action: Discontinue the tube feeding immediately if displacement is suspected.
    • Verification of Placement: Initial placement must be confirmed via radiographic X-ray. Prior to every feeding or medication administration, confirm placement by aspirating gastric contents and auscultating an injected air bolus (listening for a gurgling sound) over the upper left quadrant ($\text{ULQ}$) where the stomach lies.
    • If placement remains questionable, remove the tube to prevent pulmonary aspiration.
  • Abdominal Distension, Nausea, and Vomiting:
    • Monitor gastric residual volumes ($\text{GRV}$) using a large catheter-tip syringe prior to feedings.
    • The $300\,\text{Rule}$: If gastric residual exceeds $300\,\text{mL}$, hold/stop the feeding, notify the healthcare provider, and reduce feeding rates to prevent gastrointestinal overload.

Refeeding Syndrome: Pathophysiology, Monitoring, and Management

• Pathophysiology:
  • A severe, potentially fatal metabolic complication occurring when a severely malnourished client receives artificial refeeding (via enteral nutrition, parenteral nutrition [$\text{TPN}$, or oral intake).
  • During chronic starvation, intracellular electrolyte stores (phosphate, potassium, magnesium) are severely depleted.
  • Sudden nutritional replenishment introduces carbohydrates, triggering a rapid release of insulin. This insulin surge drives glucose, potassium, magnesium, and phosphate out of the vascular space and into the cells to metabolize food.
• Hallmark Laboratory Findings:
  • Hypophosphatemia: The cardinal laboratory sign.
  • Hypokalemia and Hypomagnesemia.
  • Extracellular Fluid Overload: Intravascular fluid retention occurs concurrently alongside electrolyte depletion.
• Clinical Consequences and Causes of Death:
  • Lethal cardiac dysrhythmias secondary to potassium and magnesium depletion.
  • Severe neuromuscular excitability and seizures caused by rapid shifts in sodium and potassium.
  • Congestive heart failure secondary to fluid volume shifts.
  • Onset typically occurs within the first $10\,\text{days}$ of reintroducing nutrition.
• Nursing and Medical Management:
  • Prevention: Start feedings at a very low caloric rate and titrate upward slowly ("start low, go slow").
  • Immediate Action upon Suspicion: Stop the tube feeding immediately, obtain stat serum electrolytes, notify the healthcare provider, and manage electrolyte replacement intravenously.
  • Clients experiencing refeeding syndrome require acute hospital admission; management cannot occur in an outpatient setting.

Questions & Discussion

• Question on Skin Coloration in Eating Disorders:
  • Query: What causes skin yellowing in anorexia nervosa, and why is it not seen in bulimia nervosa?
  • Explanation: In severe anorexia, the body depletes glycogen and turns to catabolizing muscle and cellular fats. The liver increases bile secretion to process these endogenous lipids, leading to a yellowed skin hue. Concurrent severe anemia alters baseline vascular flush, heightening the discoloration. Clients with bulimia typically maintain normal fat stores and do not experience severe metabolic catabolism.
• Question on Cognitive Distortions in Adolescent Anorexia:
  • Query: Which statement reflects catastrophizing in an anorexic client, and how are other common cognitive distortions categorized?
  • Response Breakdown:
    • Catastrophizing: Focusing on the absolute worst possible outcome regarding food or weight.
    • Personalization: Interpreting external events or attitudes personally (e.g., "Don't pretend like you don't know how bad I am").
    • Overgeneralization: Drawing expansive life conclusions from isolated physical traits (e.g., "If I could be skinny, I know I will be popular").
    • Distorted Body Image: Direct perceptual inaccuracy regarding size (e.g., viewing oneself as obese when emaciated).
• Question on Binge-Eating Disorder Management:
  • Query: What is the most accurate response to a client feeling out of control with binge eating?
  • Response: Validate that proven pharmacological treatments and behavioral therapies exist. Binge eating is not treated simply as primary obesity with strict caloric restriction, as severe restriction between binges perpetuates malnutrition.
• Discussion on the Emerging Use of GLP-1 Receptor Agonists:
  • Query: Could GLP-1 receptor agonists be utilized to curb cravings in binge-eating patterns associated with bulimia?
  • Discussion: While GLP-1 agonists effectively reduce binge eating by suppressing appetite, their application in bulimia nervosa presents significant safety risks. Bulimic clients alternate between single massive binges and severe daily food restriction; overwhelming chemical appetite suppression could induce complete starvation, worsening clinical malnutrition.