|Classification and external resources|
Refeeding syndrome is a syndrome consisting of metabolic disturbances that occur as a result of reinstitution of nutrition to patients who are starved or severely malnourished. The syndrome was first described after World War II in Americans who, held by the Japanese as prisoners of war, had become malnourished during captivity and who were then released to the care of United States personnel in the Philippines.
Any individual who has had negligible nutrient intake for more than 5 consecutive days is at risk of refeeding syndrome. Refeeding syndrome usually occurs within four days of starting to feed. Patients can develop fluid and electrolyte disorders, especially hypophosphatemia, along with neurologic, pulmonary, cardiac, neuromuscular, and hematologic complications.
During prolonged fasting the body aims to conserve muscle and protein breakdown by switching to ketone bodies derived from fatty acids as the main energy source. The liver decreases its rate of gluconeogenesis thus conserving muscle and protein. Many intracellular minerals become severely depleted during this period, although serum levels remain normal. Importantly, insulin secretion is suppressed in this fasted state and glucagon secretion is increased.
During refeeding, insulin secretion resumes in response to increased blood sugar; resulting in increased glycogen, fat and protein synthesis. This process requires phosphates, magnesium and potassium which are already depleted and the stores rapidly become used up. Formation of phosphorylated carbohydrate compounds in the liver and skeletal muscle depletes intracellular ATP and 2,3-diphosphoglycerate in red blood cells, leading to cellular dysfunction and inadequate oxygen delivery to the body's organs. Refeeding increases the basal metabolic rate. Intracellular movement of electrolytes occurs along with a fall in the serum electrolytes, including phosphate, potassium and magnesium. Glucose, and levels of the B vitamin thiamine may also fall. Cardiac arrhythmias are the most common cause of death from refeeding syndrome, with other significant risks including confusion, coma and convulsions and cardiac failure.
This syndrome can occur at the beginning of treatment for anorexia nervosa when patients have an increase in calorie intake and can be lethal. The shifting of electrolytes and fluid balance increases cardiac workload and heart rate. This can lead to acute heart failure. Oxygen consumption is also increased which strains the respiratory system and can make weaning from ventilation more difficult.
Refeeding syndrome can be fatal if not recognized and treated properly. An awareness of the condition and a high index of suspicion are required in order to make the diagnosis. Refeeding syndrome occurs most commonly in those who have lost weight rapidly. The electrolyte disturbances of the refeeding syndrome can occur within the first few days of refeeding, which can be undertaken through the oral or nasogastric routes. Close monitoring of blood biochemistry is therefore necessary in the early refeeding period. Milk is often the refeeding food of choice in this early period as it is naturally high in phosphate and easily tolerated by those who have been starved. If potassium, phosphate or magnesium are low then this should be corrected via the oral route, or if severe with parenteral treatment. Prescribing thiamine, vitamin B complex (strong) and a multivitamin and mineral is recommended. Biochemistry should be monitored regularly until it is stable. Energy intake should remain only 50-70% that of normally required for the first 3–5 days.
Patients who have been starved for some time often experience gastrointestinal disturbance during refeeding, in particular colicky abdominal pain, reflux symptoms, nausea and early satiety. To help manage this, patients are often prescribed pro-kinetic agents such as domperidone or metoclopramide, as well as acid suppressants such as omeprazole. This may be of particular importance in patients suffering from anorexia nervosa, who can find these symptoms particularly distressing.
- Minnesota Starvation Experiment where some effects of refeeding were documented.
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