Fellow Mount Sinai Health System New York, New York, United States
Introduction : Although the awareness of malnutrition among elderly people is well established, the risk of Refeeding Syndrome (RFS) is often neglected, especially in the frail elderly population. This partly relates to the unspecific clinical presentation and laboratory changes in the geriatric population. We present a case of RFS presenting as severe hypoglycemia in an elderly patient after initiating enteral nutrition.
Case(s) Description : A 93-year-old female with history of heart failure, coronary artery disease, and dementia presented with severe abdominal pain, constipation, and failure to thrive. She had poor oral intake for the last few months with severe malnutrition. Her physical examination was significant for severe lethargy and BMI of 16.2. Her labs showed serum sodium of 173 mEq/L and blood glucose of 86 mg/dL. She received hypotonic fluids for hypernatremia. A nasogastric tube was inserted for enteral nutrition and free water flushes. As enteral nutrition was advanced from 6 kcal/kg to 13 kcal/kg after 6 hours, she developed severe hypoglycemia with blood glucose of 27 mg/dL requiring intramuscular glucagon. Over the next 24 hours, she had recurrent episodes of hypoglycemia, and the Endocrinology service was consulted. During one of the episodes, her labs showed serum C-peptide levels elevated at 14.2 ng/ml (normal 1.1-4.4 ng/ml) and serum Insulin levels elevated at 32.4 uU/ML (normal 1.9 - 23.0 uU/ML). Initially her hypoglycemia was attributed to severe malnutrition and critical illness, however when labs were concerning for inappropriately high serum insulin concentration, there was concern for endogenous excessive insulin production. Since large glucose loads like tube feeds can stimulate substantial amounts of insulin release from the pancreas, which cannot be offset by the depleted hepatic reserves of glycogen reserves and gluconeogenesis substrates in severely malnourished patients, diagnosis of RFS was considered to be the likely etiology. Over the course, the enteral nutrition was advanced slowly with 10 kcal/kg increments daily, and the hypoglycemia resolved.
Discussion : RFS can be characterized by severe electrolyte shifts (mainly hypophosphatemia, hypomagnesemia, and hypokalemia), vitamin deficiency (mainly thiamine), fluid overload, and salt retention leading to organ dysfunction and cardiac arrhythmias. Hypoglycemia is generally less known to clinical providers as part of the spectrum. Various studies and guidelines have shown a beneficial effect of starting energy intake at a lower rate to prevent RFS. Refeeding should commence at 5-10 kcal/kg per day in patients at risk and should be advanced slowly. The awareness of the medical and nursing staff is often too low in clinical practice, leading to under-diagnosis of this complication. Our case emphasizes the importance of consideration of RFS as the cause of hypoglycemia in similar patients.
