What is refeeding syndrome, its causes, laboratory changes, and management?

From the Guidelines

Refeeding syndrome is a potentially fatal metabolic complication that occurs when nutritional support is reintroduced too rapidly in severely malnourished patients, and it should be managed by starting with 5-10 kcal/kg/day and gradually increasing over 5-7 days while closely monitoring electrolytes and providing prophylactic supplementation with phosphate, potassium, magnesium, and thiamine. This condition is caused by the sudden shift from fat to carbohydrate metabolism, triggering insulin release that drives electrolytes (particularly phosphate, potassium, and magnesium) into cells, resulting in dangerously low serum levels 1. Common causes include chronic alcoholism, anorexia nervosa, prolonged fasting, uncontrolled diabetes, chronic malnutrition, and extended periods without nutrition. Laboratory changes typically show hypophosphatemia (most significant), hypokalemia, hypomagnesemia, fluid retention, and sometimes hypoglycemia.

• Key laboratory parameters to monitor include phosphate, potassium, magnesium, and glucose levels 1.
• Prophylactic supplementation should include phosphate (20-40 mmol/day), potassium (1-3 mmol/kg/day), magnesium (8-12 mmol/day), and thiamine (200-300 mg daily) before and during the first 10 days of refeeding 1.
• Daily laboratory monitoring is essential during the first week, with electrolyte replacement adjusted based on serum levels.
• Fluid administration should be restricted to 20-30 ml/kg/day with careful monitoring for edema. This cautious approach allows metabolic adaptation while preventing the dangerous electrolyte shifts that can lead to cardiac arrhythmias, seizures, respiratory failure, and death if refeeding is too aggressive. The most recent and highest quality study 1 supports this approach, emphasizing the importance of careful monitoring and supplementation to prevent refeeding syndrome.

From the Research

Definition and Causes of Refeeding Syndrome

• Refeeding syndrome (RS) is characterized by electrolyte imbalances that can occur in malnourished and abruptly refed patients 2, 3.
• The sudden increase in food intake causes a shift in the body's metabolism and electrolyte balance, leading to symptoms such as weakness, seizures, and even heart failure 2.
• RS reflects the change from catabolic to anabolic metabolism 3.
• The presence of hypophosphatemia alone does not necessarily mean that RS is present, as there are many other causes for this 3.

Laboratory Changes

• Typical features of RS are hypophosphatemia, hypokalemia, hypomagnesemia, and thiamine deficiency 2, 4.
• Electrolyte imbalances, including low serum concentrations of intracellular ions such as phosphate, magnesium, and potassium, are a key characteristic of RS 3, 4.
• Close monitoring of electrolyte levels is critical to prevent and manage RS 2, 5.

Management of Refeeding Syndrome

• A proper management with progressive increase in nutrients is essential to prevent the onset of RS and ensure the best possible outcomes 2.
• A proper strategy should start with small amounts of low-calorie fluids and gradually increasing the calorie content and amount of food over several days 2.
• Prophylactic use of dietary supplements such as thiamine may be required to correct any imbalances that may occur 2, 5.
• Careful patient monitoring and multidiscipline nutrition team management may help to achieve the goal of preventing and managing RS 3.
• An evidence-based and consensus-supported algorithm for the management and prevention of RS in medical inpatients has been proposed, including risk assessment, diagnostic criteria, and preventive and therapeutic measures 6.