Nutrition Diet · Supplementary · from Nutrition Diet

Case 2: Refeeding Syndrome

Patient Presentation

Demographics: 22-year-old female college student

Chief Complaint: Brought to emergency department by roommate for "confusion and not eating for weeks."

History of Present Illness: Ms. Garcia is a 22-year-old college senior brought to the ED by her roommate, who reports that the patient has been eating "almost nothing" for the past three weeks and has become increasingly confused and lethargic over the past 24 hours. The roommate states that Ms. Garcia has been under extreme academic pressure and has been restricting food intake, initially skipping meals and progressing to consuming only water, black coffee, and occasional crackers.

The patient has a known history of anorexia nervosa, diagnosed at age 16, with multiple treatment episodes. She was weight-restored and in partial remission for the past 18 months but relapsed at the start of the current semester. She has lost approximately 20 pounds over the past 6 weeks, declining from 115 pounds to 95 pounds (BMI declining from 19.7 to 16.3).

Upon ED presentation, she is oriented to person and place but not to time. She is hypotensive and bradycardic. The ED team recognizes her as severely malnourished and begins intravenous dextrose-containing fluids and plans to initiate enteral nutrition. This case illustrates the critical importance of recognizing refeeding risk before initiating nutritional rehabilitation.

Past Medical History:

• Anorexia nervosa, restricting type (diagnosed age 16; two prior inpatient admissions)
• Secondary amenorrhea (intermittent)
• Osteopenia (diagnosed age 19)
• Major depressive disorder

Medications:

• Fluoxetine 40 mg daily (has not been taking for 2 weeks)
• Multivitamin (has not been taking)

Social History:

• College senior; pre-law track
• Lives in campus housing with roommate
• Non-smoker; no alcohol or drug use
• High academic achiever; describes perfectionist traits
• Estranged from parents; limited support system

Family History:

• Mother: Generalized anxiety disorder
• Maternal aunt: Anorexia nervosa

Physical Examination

• Vital Signs: BP 82/54 mmHg (supine), HR 48 bpm, RR 12, Temp 96.8°F, SpO2 96%, BMI 16.3 kg/m²
• General: Cachectic, lethargic young female; temporal wasting; prominent bony landmarks
• HEENT: Sunken eyes; dry, cracked lips; lanugo hair on face; parotid gland enlargement bilateral (mild); dental enamel erosion not present (restricting subtype)
• Cardiovascular: Bradycardic; regular rhythm; distant heart sounds; no murmurs; weak peripheral pulses; capillary refill 4 seconds
• Respiratory: Clear but diminished breath sounds at bases; shallow respirations
• Abdomen: Scaphoid; hyperactive bowel sounds; no tenderness
• Extremities: Marked muscle wasting; cold, mottled, acrocyanotic hands and feet; trace pedal edema; no deep vein thrombosis signs
• Skin: Dry, lanugo hair on arms and back; bruising on shins; poor turgor
• Neurological: Oriented x2; lethargic but arousable; diminished deep tendon reflexes globally; Chvostek sign positive (facial twitching with tapping of facial nerve); Trousseau sign positive (carpopedal spasm with BP cuff inflation)

Workup and Results

Laboratory Studies (on admission, BEFORE refeeding):

After initiation of IV dextrose (Day 2 — demonstrating refeeding shift):

Imaging/Additional Studies:

• ECG (admission): Sinus bradycardia 48 bpm; prolonged QTc 512 ms; flattened T-waves; U-waves present
• ECG (Day 2, post-refeeding): New ST-depression V4-V6; QTc 548 ms
• Echocardiogram: Reduced LV mass; EF 45% (mildly reduced); small pericardial effusion
• Chest X-ray: Small bilateral pleural effusions; no pulmonary edema

Clinical Image

Pathophysiology of refeeding syndrome illustrating the metabolic shift: during starvation, the body adapts to fat and ketone metabolism with depleted intracellular electrolyte stores. Upon carbohydrate reintroduction, insulin surges drive glucose, phosphorus, potassium, and magnesium intracellularly, causing precipitous serum drops that can lead to cardiac arrhythmias, respiratory failure, seizures, and death. Source: Educational illustration.

Diagnosis

Refeeding Syndrome (ICD-10: E43, E83.39, E87.6)

Key Diagnostic Criteria:

• Severely malnourished patient (BMI 16.3, minimal intake for 3+ weeks)
• Precipitous drop in phosphorus from 1.8 to 0.8 mg/dL after carbohydrate reintroduction (hallmark of refeeding syndrome)
• Concurrent worsening of potassium and magnesium
• ECG deterioration (prolonging QTc, new ST changes)
• Clinical deterioration after initiation of IV dextrose
• NICE criteria for high refeeding risk met: BMI < 18.5, unintentional weight loss > 15%, negligible intake > 10 days, and low baseline electrolytes

Treatment Plan

1. STOP Dextrose-Containing Fluids Immediately: The IV dextrose triggered the refeeding cascade; switch to normal saline without dextrose
2. Phosphorus Replacement (Priority): IV sodium phosphate or potassium phosphate 30-45 mmol over 6 hours with cardiac monitoring; recheck phosphorus every 6 hours; maintain > 2.0 mg/dL
3. Potassium Replacement: IV potassium chloride 40 mEq over 4 hours (central line preferred given concentration); continuous cardiac monitoring; target > 3.5 mEq/L; do NOT replace potassium in dextrose-containing solutions
4. Magnesium Replacement: IV magnesium sulfate 2 g over 2 hours; magnesium must be repleted before potassium will correct (magnesium depletion causes renal potassium wasting)
5. Thiamine Replacement (BEFORE any carbohydrate): IV thiamine 200-300 mg daily for 3 days, then oral 100 mg daily; thiamine MUST precede carbohydrate administration to prevent Wernicke encephalopathy — the dextrose given without thiamine was a critical error
6. Cautious Refeeding Protocol: Start at 10 kcal/kg/day (approximately 430 kcal/day); advance by 5 kcal/kg/day every 24-48 hours if electrolytes remain stable; goal of 30-40 kcal/kg/day by day 7-10; use low-carbohydrate, moderate-fat formulations initially
7. Continuous Cardiac Monitoring: ICU admission; telemetry for QTc monitoring (risk of torsades de pointes); daily ECGs
8. Electrolyte Monitoring: BMP every 6-8 hours for first 72 hours; daily thereafter for 5-7 days; phosphorus, magnesium, and potassium checked together always
9. Multidisciplinary Team: Psychiatry, nutrition, internal medicine, cardiology co-management; transition to eating disorder unit when medically stable
10. Long-term Plan: Residential eating disorder treatment program referral; family therapy; relapse prevention planning

Key Learning Points

• Refeeding syndrome is a potentially lethal metabolic complication characterized by severe hypophosphatemia, hypokalemia, and hypomagnesemia occurring when carbohydrates are reintroduced to a severely malnourished patient
• Hypophosphatemia is the hallmark of refeeding syndrome — phosphorus is consumed by ATP synthesis and 2,3-DPG production during the sudden shift from fat to carbohydrate metabolism; levels below 1.0 mg/dL can cause respiratory failure, cardiac arrest, and death
• Thiamine must ALWAYS be administered before any carbohydrate in malnourished patients — glucose metabolism consumes thiamine, and administering glucose to a thiamine-depleted patient can precipitate Wernicke encephalopathy
• The NICE guidelines identify five risk criteria for refeeding syndrome: BMI < 18.5, unintentional weight loss > 10% in 3-6 months, little/no nutritional intake > 5 days, low baseline phosphorus/potassium/magnesium, and history of alcohol misuse or certain medications (insulin, chemotherapy, diuretics)
• The initial refeeding rate should be 10 kcal/kg/day for high-risk patients (5 kcal/kg/day for extreme risk, BMI < 14), with slow advancement — "start low and go slow" is the cardinal rule of nutritional rehabilitation

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