Reprinted from Eating Disorders Review
March/April 2003 Volume 13, Number 2
©2002 Gürze Books
The refeeding syndrome, severe hypophosphatemia and associated metabolic complications, is well documented in patients with anorexia nervosa. Such patients have depleted stores of potassium, magnesium, and calcium, changes in glucose metabolism, dramatic fluid shifts, and thiamin deficiency. These rapid metabolic changes can create life-threatening conditions such as cardiac arrhythmias and heart failure.
It is interesting to note that almost all reports of hypophosphatemia have occurred after the use of parenteral nutrition. (Parenteral nutrition involves feeding through a source other than the alimentary tract, such as using an intravenous line.) Although I have seen this complication occur during oral renourishment, there are no published cases to date. In 1996, however, Dr. C. Laird Birmingham and colleagues at St. Paul’s Hospital (SPH) published what is believed to be the first case in which hypophosphatemia occurred during enteral (oral and tube feeding) nutrition support. During the renourishment process, a 22-year-old woman with anorexia nervosa developed heart failure secondary to hypophosphatemia brought on by aggressive nasogastric tube feeding (NGTF).
For Dr. Birmingham and the SPH inpatient eating disorders treatment team, the case of the 22-year-old woman was a wake-up call. To reduce the risk of refeeding syndrome, they developed a formalized refeeding protocol with specific recommendations for prophylactic phosphorus supplementation.
Regardless of the route of nutrient delivery (oral, enteral, or parenteral), chronically malnourished patients require close medical monitoring during refeeding. Table 1 shows the most current protocol used at St. Paul’s Hospital, Vancouver, when refeeding patients orally or by NGTF. Table 2 describes the recommended steps for monitoring patients during inpatient admission. It is important to emphasize that the following treatment recommendations are based solely on the opinion of clinicians at St. Paul’s Hospital.
Nutrition Goals of Refeeding
First, nutritional deficiencies are corrected. If the patient’s serum magnesium, electrolytes, and phosphorus are normal, begin routine supplementation according to standard admission orders. Continue to monitor blood tests every 2 to 3 days. Routine supplementation of phosphorus and potassium is essential to reduce the risk of refeeding syndrome even if the initial blood tests are normal.
If the blood tests are abnormal, deficiencies are corrected with the use of oral supplements or an intravenous (IV) line. The severity of the deficiency determines the most appropriate mode of supplement delivery. If the serum blood work is significantly below normal, consult with the team physician to determine whether IV repletion is necessary. Low serum magnesium always requires IV supplementation because intestinal absorption of oral magnesium is not efficient enough to correct blood levels quickly.
If an IV preparation is necessary, normal saline, rather than dextrose solution, is recommended because it reduces the patient’s insulin response and potentially lowers the risk of refeeding complications. Repeat blood tests on a daily basis until the serum values for magnesium, potassium, and phosphorus have normalized. Nutrient repletion may take several days and aggressive refeeding should be avoided during this time.
Next, weight loss is stabilized and weight restoration begun.The inpatient dietitian meets with the patient on admission to create an individualized meal plan. A maximum intake of 800 kcal/day is recommended for patients with abnormal serum values. Once blood test results normalize, the patient’s energy intake can be gradually increased.
Patients with normal blood work can begin refeeding with a meal plan that meets their estimated basal energy requirements for metabolic stabilization. This value is determined by using the Harris-Benedict Equation and is almost always between 1200 to 1600 kcal/day. For the weight in this equation, use ideal body weight or the patient’s weight at a BMI of 20. The Harris-Benedict Equation calculates only the patient’s basal energy requirements (i.e., the amount of energy expended by the body to maintain vital processes such as respiration and circulation)
The goal is a 1- to 2-kg weight increase each week. In collaboration with the patient, the dietitian increases the meal plan weekly by 500 to 700 kcal/day each week to achieve this weight gain goal. Meal plan adjustments are made until the desired energy intake is established. Caloric needs for weight gain vary widely and may range from 2000 kcal/day to more than 4000 kcal/day. For patients admitted with a body mass index (BMI) of 20 or greater, work to establish an energy intake that promotes weight maintenance and a healthy eating pattern.
During the first 24 hours of the patient’s hospital stay, the inpatient treatment team assesses the patient’s ability to eat and use liquid supplement to meet 100% of their meal plan. Patients not able to meet their nutritional needs through oral intake require nasogastric tube feeding (NGTF).
NGTF is initiated if necessary. A 1 kcal/ml formula is recommended when initiating NGTF. The safest rate to start the tube feeding depends on the severity of the patient’s malnutrition. For patients who are above 75% of median ideal body weight (BMI=22.5), start NGTF at 50 ml/hr for 24 hours/day. Monitor serum glucose, magnesium, phosphorus and potassium every 2 to 3 days.
For patients who weigh less than 75% of median ideal body weight, initiate tube feeding at 25 ml/hr for 24 hr/day. Serum glucose, magnesium, phosphorus and potassium are monitored daily for the first 3 to 5 days. If blood work remains stable during this time monitoring can be reduced to three times a week (e.g., Monday, Wednesday, and Friday).
Increase the NGTF rate to 50 ml/hour after serum values have remained stable for a 36- to 48-hour period.
If serum values drop below normal at any time, supplementation is increased, to correct the deficiencies, but the NGTF rate is not increased until the serum values are stable again. After a 48- to 72-hr period, if the blood work has remained stable, increase the NGTF rate to 75 ml/hr for 24 hours/day. Continue to monitor blood work every 2 to 3 days.
After another 48 to 72 hours, tube feeds can be increased to 100 ml/hr and progress to the final rate can be made by increasing the rate every 48 to 72 hr. The goal NGTF rate can be calculated using the Harris-Benedict Equation (1.2-1.3 as the stress factor and adding an extra 500 -1000 kcal/day for weight gain). Continue to monitor the blood work at least 2 to 3 times weekly. If higher NGTF rates are not well tolerated by the patient, a more energy-dense formula (e.g., 1.5 to 2 kcal/ml) can reduce the volume of supplement needed.
The tube feeds are tapered once the patient is motivated to increase his or her oral intake. The NGTF formula is decreased by an amount equivalent to the caloric value of the patient’s oral intake and continue until the tube feeds are no longer required. Finally, monitor serum values 2 to 3 times a week.
Alateeqi, N, Allard, J. Anorexia Nervosa: From Starvation to Refeeding. Clinical Nutrition Rounds. Canadian Society for Clinical Nutrition, 1:1, 2001.
Birmingham CL, Alothman AF, Goldner EM. Anorexia nervosa: Refeeding and hypophosphatemia. Int J Eat Disord 1996; 20:2, 211.
Solomon S, Kirby D. The Refeeding Syndrome: A review. JPEN 1990; 14:90.
– Linda M. Watts, MA RD, and Donald J. Barker, RD