What is the risk of refeeding syndrome in patients with polymorbidity and how should it be managed?

Refeeding Syndrome Risk in Polymorbid Patients

Severely underweight polymorbid medical inpatients are at extremely high risk for refeeding syndrome and must have nutritional targets achieved cautiously and slowly, with energy goals of 30 kcal/kg actual body weight reached gradually rather than immediately. 1

Risk Stratification in Polymorbid Populations

Severely underweight patients (BMI <16 kg/m²) with polymorbidity represent the highest risk category for refeeding syndrome. 1 The 2024 ESPEN guidelines explicitly identify this population as requiring special precautions when initiating nutritional support. 1

Additional High-Risk Features to Identify:

• Recent unintentional weight loss >15% 2
• Very little nutritional intake for >10 days 2
• Low baseline plasma concentrations of potassium, phosphate, or magnesium before feeding 2
• History of chronic alcoholism (particularly relevant as these patients may have thiamine deficiency) 1
• Pre-existing malnutrition with BMI 15-16 kg/m² 1

Polymorbid patients with at least two of the following also warrant heightened vigilance: BMI <18.5 kg/m², recent weight loss >10%, minimal intake for >5 days, or history of alcohol abuse or medications including insulin, chemotherapy, or diuretics. 2

Management Algorithm for Polymorbid Patients at Risk

Initial Assessment and Preparation (Before Feeding):

• Measure baseline thiamine, phosphate, magnesium, and potassium levels immediately 3, 4
• Supplement deficiencies prophylactically before initiating nutrition 3, 4
• All high-risk polymorbid patients must receive high-potency vitamin preparations (including thiamine) 5
• Assess fluid status carefully, as polymorbid patients often have complex fluid balance issues 1

Nutritional Initiation Strategy:

• Start with significantly reduced calories: 12-13 kcal/kg/day initially 5
• Target energy goal of 30 kcal/kg actual body weight should be achieved slowly over several days, NOT immediately 1
• In patients with SIRS, MODS, or at refeeding risk, reduce further to 15-20 kcal/kg/day 1
• Protein targets should still aim for 1.2-1.5 g/kg/day once feeding is established 6, but this must be reached gradually alongside caloric advancement

Critical caveat: The standard energy target of 27 kcal/kg/day for polymorbid older patients (≥65 years) does NOT apply to severely underweight individuals—these patients require the cautious 30 kcal/kg target achieved slowly. 1

Monitoring Protocol:

• Monitor phosphate, magnesium, and potassium daily for the first 7 days 5, 3
• Check glucose levels frequently, as hyperglycemia is common and may require insulin 1
• Assess for fluid overload, particularly in patients with cardiac or renal comorbidities 1
• Watch for clinical signs: cardiac arrhythmias, confusion, muscle weakness, respiratory failure 3, 7

Research evidence demonstrates that even with appropriate risk assessment and preventive measures, 84% of high-risk patients developed at least one electrolyte abnormality when starting total parenteral nutrition, with hypophosphatemia occurring in 30-33% despite precautions. 5 This underscores that polymorbid patients remain vulnerable even with guideline-adherent care.

Electrolyte Replacement Thresholds:

• Aggressively supplement phosphate, magnesium, and potassium as soon as levels decline 3, 4
• Do not wait for severe depletion—early intervention prevents progression to life-threatening complications 3, 7
• Thiamine supplementation is mandatory before carbohydrate administration 1, 4

Special Considerations in Polymorbidity

Polymorbid patients with impaired kidney function (eGFR <30 ml/min/1.73m²) require modified protein targets of 0.8 g/kg/day, which adds complexity to refeeding management. 1 These patients need even more careful electrolyte monitoring as their ability to excrete excess electrolytes is compromised.

Drug-nutrient interactions are particularly problematic in polymorbid populations taking multiple medications. 1 A pharmacist-assisted management plan should be established to identify potential interactions that could exacerbate refeeding complications. 1

Common Pitfalls to Avoid

• Do not use aggressive refeeding despite the temptation to rapidly correct severe malnutrition—this significantly increases mortality risk. 6, 3
• Do not assume that low-risk polymorbid patients are immune to refeeding syndrome—research shows 20% of "low-risk" patients still developed hypophosphatemia. 5
• Do not overlook the severely underweight polymorbid patient who appears stable—refeeding syndrome can manifest 16-48 hours after nutrition initiation. 2
• Do not forget thiamine supplementation—Wernicke's encephalopathy can develop rapidly in malnourished polymorbid patients, especially those with alcohol history. 1, 4
• Avoid fluid overload, which is particularly dangerous in polymorbid patients with cardiac or renal disease and can precipitate abdominal compartment syndrome in severe cases. 1

Outcome Impact

The gradual feeding approach is critical for reducing mortality and morbidity in this vulnerable population. 6, 3 While the goal remains achieving adequate nutrition (1.2-1.5 g protein/kg/day and 30 kcal/kg/day) to prevent body weight loss, reduce complications, and improve functional outcomes, 6 the speed of achieving these targets determines whether the patient survives the refeeding process. 1

Refeeding syndrome remains poorly recognized against the background of severe disease and multimorbidity, 4 making heightened clinical suspicion essential in all severely underweight polymorbid inpatients.