Refeeding syndrome

Refeeding syndrome is a syndrome consisting of metabolic disturbances that occur as a result of reinstitution of nutrition to patients who are starved, severely malnourished or metabolically stressed due to severe illness. When too much food and/or liquid nutrition supplement is consumed during the initial four to seven days of refeeding, this triggers synthesis of glycogen, fat and protein in cells, to the detriment of serum (blood) concentrations of potassium, magnesium and phosphorus. Cardiac, pulmonary and neurological symptoms can be signs of refeeding syndrome. The low serum minerals, if severe enough, can be fatal. Refeeding syndrome is a syndrome consisting of metabolic disturbances that occur as a result of reinstitution of nutrition to patients who are starved, severely malnourished or metabolically stressed due to severe illness. When too much food and/or liquid nutrition supplement is consumed during the initial four to seven days of refeeding, this triggers synthesis of glycogen, fat and protein in cells, to the detriment of serum (blood) concentrations of potassium, magnesium and phosphorus. Cardiac, pulmonary and neurological symptoms can be signs of refeeding syndrome. The low serum minerals, if severe enough, can be fatal. Any individual who has had a negligible nutrient intake for many consecutive days and/or is metabolically stressed from a critical illness or major surgery is at risk of refeeding syndrome. Refeeding syndrome usually occurs within four days of starting to re-feed. Patients can develop fluid and electrolyte disorders, especially hypophosphatemia, along with neurologic, pulmonary, cardiac, neuromuscular, and hematologic complications. During fasting the body switches its main fuel source from carbohydrates to fat tissue fatty acids and amino acids as the main energy sources. The spleen decreases its rate of red blood cell breakdown thus conserving red blood cells. 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 phosphorus and magnesium. Levels of serum glucose may rise and the B1 vitamin thiamine may fall. Abnormal heart rhythms 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 fatal. It can also occur after the onset of a severe illness or major surgery. 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.