Refeeding syndrome

Overview

Refeeding syndrome is a potentially life-threatening metabolic disturbance that occurs when nutrition is reintroduced too rapidly after a period of prolonged fasting or severe malnutrition. It is characterized by sudden shifts in fluids and electrolytes, particularly phosphate, potassium, and magnesium, which can lead to severe complications such as cardiac arrhythmias, respiratory failure, and neurological disturbances.

This syndrome most commonly occurs in individuals with chronic starvation, eating disorders (such as anorexia nervosa), cancer cachexia, alcoholism, or those recovering from prolonged illness or surgery without adequate nutrition. Refeeding syndrome is preventable with appropriate screening and gradual nutritional rehabilitation, but unrecognized cases can result in high morbidity and mortality.

Causes

Refeeding syndrome is triggered by the sudden reintroduction of carbohydrates and calories into a body that has adapted to a low-nutrient state. The underlying pathophysiology involves hormonal and metabolic changes that affect electrolyte and fluid balance.

Mechanism:

• During starvation, the body shifts from glucose metabolism to fat and protein metabolism to conserve energy.

• Insulin secretion is suppressed, and intracellular stores of electrolytes (phosphate, potassium, and magnesium) become depleted even though serum levels may appear normal.

• When feeding is resumed—especially with carbohydrate-rich meals—insulin levels rise rapidly, prompting a shift of glucose and electrolytes into cells.

• This leads to a rapid drop in serum phosphate, potassium, and magnesium levels, triggering the symptoms of refeeding syndrome.

Common Risk Factors:

• Prolonged fasting or starvation (more than 5–10 days)

• Chronic alcoholism

• Uncontrolled diabetes or insulin therapy

• Malabsorptive disorders (e.g., inflammatory bowel disease)

• Post-surgical patients, especially after bariatric or gastrointestinal surgery

• Cancer or advanced chronic illnesses

• Use of chemotherapy or diuretics

Symptoms

The symptoms of refeeding syndrome typically emerge within the first few days of initiating refeeding. The severity depends on the degree of electrolyte imbalance and the rapidity of nutritional repletion.

Common Clinical Features:

• Hypophosphatemia: The hallmark feature, leading to muscle weakness, rhabdomyolysis, respiratory failure, hemolysis, and cardiac dysfunction

• Hypokalemia: Can cause arrhythmias, muscle cramps, and paralysis

• Hypomagnesemia: May result in tetany, seizures, and cardiac arrhythmias

• Fluid overload: Due to sodium and water retention, may lead to peripheral edema or pulmonary edema

• Thiamine deficiency: Can lead to Wernicke’s encephalopathy (confusion, ataxia, ophthalmoplegia)

Additional Symptoms:

• Fatigue and weakness

• Shortness of breath

• Confusion or altered mental status

• Hypotension or tachycardia

• Nausea or vomiting

Diagnosis

Refeeding syndrome is primarily a clinical diagnosis based on risk factors, nutritional history, and laboratory findings following the initiation of feeding. Early recognition is crucial to prevent complications.

Diagnostic Criteria (Suggested):

According to the National Institute for Health and Care Excellence (NICE), a person is at high risk if they meet one or more of the following:

• Body Mass Index (BMI) less than 16 kg/m²

• Unintentional weight loss greater than 15% in 3–6 months

• Very little or no nutritional intake for more than 10 days

• Low levels of phosphate, potassium, or magnesium before feeding

Investigations:

• Serum electrolytes: Phosphate, potassium, magnesium, calcium, sodium

• Liver and renal function tests

• ECG: To detect cardiac arrhythmias

• Serum glucose and insulin levels

• Thiamine levels (optional but may be considered in at-risk individuals)

Treatment

Treatment of refeeding syndrome involves correcting electrolyte imbalances, slowing down the refeeding process, and close monitoring. The goal is to restore nutrition safely while minimizing metabolic stress.

Immediate Management:

• Stop or reduce feeding rate: If severe symptoms or electrolyte imbalances are detected

• Correct electrolyte deficiencies: Administer phosphate, potassium, and magnesium intravenously or orally as needed

• Thiamine supplementation: 100–300 mg daily before and during refeeding to prevent Wernicke’s encephalopathy

• Fluids: Carefully manage fluid intake to avoid overload; restrict sodium if needed

Refeeding Strategy:

• Start with low-calorie feeds (approximately 10 kcal/kg/day) in high-risk patients

• Increase caloric intake gradually over 4–7 days

• Monitor weight, electrolytes, vital signs, and fluid balance daily

• Provide multivitamin and trace element supplementation

Multidisciplinary Approach:

• Involve dietitians, physicians, and nurses in planning and monitoring the refeeding protocol

• Consider psychiatric or social work support in patients with eating disorders or substance abuse

Prognosis

The prognosis of refeeding syndrome depends on early recognition, appropriate management, and the underlying health condition of the patient. With timely intervention and careful monitoring, most patients recover without permanent complications.

However, untreated or severe cases can lead to fatal outcomes, including cardiac arrest, respiratory failure, or neurological damage. The risk of mortality is significantly higher in patients with multiple comorbidities, advanced malnutrition, or delay in diagnosis.

Prevention is the best strategy, identifying at-risk individuals, initiating slow refeeding, and close monitoring can dramatically reduce the incidence and severity of refeeding syndrome. Education and standardized protocols in hospitals and long-term care settings are critical to ensuring patient safety during nutritional rehabilitation.