NurseSavvy Cheat SheetDisease
Anorexia Nervosa & Bulimia Nervosa
Pathophysiology & Risk Factors
Anorexia nervosa is severe caloric restriction driven by intense fear of weight gain and distorted body image, producing markedly low body weight. Bulimia nervosa is recurrent binge-purge cycles in a client typically at or near normal weight, making it harder to detect. Both carry cardiac risk; the gravest threat in anorexia is refeeding syndrome when nutrition is restored too quickly.
Anorexia nervosa vs bulimia nervosa
Anorexia nervosaBulimia nervosa
WeightMarkedly low / emaciatedOften normal or above normal
Core behaviorCaloric restrictionBinge then purge
Hallmark physical signsLanugo, amenorrhea, bradycardia, hypothermiaRussell sign, dental enamel erosion, parotid swelling
Key metabolic riskRefeeding syndrome (hypophosphatemia)Hypokalemia with metabolic alkalosis
Anorexia nervosa
- Weight
- Markedly low / emaciated
- Core behavior
- Caloric restriction
- Hallmark physical signs
- Lanugo, amenorrhea, bradycardia, hypothermia
- Key metabolic risk
- Refeeding syndrome (hypophosphatemia)
Bulimia nervosa
- Weight
- Often normal or above normal
- Core behavior
- Binge then purge
- Hallmark physical signs
- Russell sign, dental enamel erosion, parotid swelling
- Key metabolic risk
- Hypokalemia with metabolic alkalosis
Signs & Symptoms
lanugo Hallmark
anorexiaamenorrhea
anorexiabradycardia Hallmark
anorexiahypothermia
anorexiahypotension
anorexiaRussell sign Hallmark
knuckle calluses; bulimia purging markerdental enamel erosion
bulimia; chronic purgingparotid gland swelling
bulimia purging markerweakness
may signal hypokalemia in purgingheart palpitations
electrolyte-driven; bulimiaDiagnostics & Labs
Diagnostic
significantly low body weight Hallmark
key feature distinguishing anorexia from bulimiametabolic alkalosis
from repeated self-induced vomitingMonitor
serum potassiumK+ < 3.5 mEq/L
hypokalemia from purging; arrhythmia riskserum phosphorusphosphorus < 2.5 mg/dL
hallmark of refeeding syndromeserum magnesium
hypomagnesemia in refeedingcontinuous cardiac monitoring
QTc prolongation, dysrhythmia surveillanceInterventions & Priorities
obtain baseline electrolytes
phosphorus, magnesium, potassium, calciumplace on cardiac monitor
establish baseline before refeedingadvance calories gradually
start low per protocol; prevents insulin-driven shiftssupervise all meals
observe 1-2 hours after meals
prevents purging or food disposalmonitor electrolytes first 72 hours
highest-risk refeeding windowtrend daily weights and I&O
ongoing trajectory; sudden gain may be fluidTreatments & Medications
IV phosphorus replacement
for hypophosphatemia of refeedingthiamine administration
given during refeedingpotassium replacement
for purging-induced hypokalemiastructured meal plan
framed as prescribed treatment, non-negotiablePatient Teaching
daily weight same time
hospital gown, after voiding, same scalemeals as prescribed treatment
calm, matter-of-fact, avoid negotiating portionsavoid food power struggles
focus on feelings, not caloriesnonjudgmental mealtime environment
Complications
lethal cardiac dysrhythmia
from hypokalemia < 3.5 mEq/Lcardiac failure
refeeding hypophosphatemiarespiratory failure
severe refeedingseizures
refeeding electrolyte shiftsReport Nowescalate immediately
Report-now threshold
Hypokalemia (dysrhythmia risk)
Normal potassium
Hyperkalemia
2
3.5
5
6
mEq/L
hypokalemiaK+ < 3.5 mEq/L
predisposes to lethal dysrhythmiahypophosphatemiaphosphorus < 2.5 mg/dL
hallmark of refeeding syndromehypomagnesemia
refeeding electrolyte shiftQTc prolongation
most life-threatening refeeding signsevere bradycardia
anorexia HR in 40shypotension
hemodynamic instabilityrapid fluid retention
edema with sudden weight gain; refeedingClinical Pearl
Refeeding kills through phosphate, not food — when you restart nutrition in a starved client, watch phosphorus before you worry about the meal plan.