NAPLEX Question of the Week: Nutrition

This week we hit a major topic within nutrition that is critical.

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BD is a 68-year-old woman with cancer cachexia. She has lost 10% of her body weight since her diagnosis with colon cancer about 6 months ago. Her cancer treatments are causing severe nausea and vomiting. The physician wants to start parenteral nutrition. The dietitian expresses concern regarding refeeding syndrome. Which electrolyte abnormalities are characteristic of this syndrome? Select all that apply.

a. Hypomagnesemia

b. Hypercalcemia

c. Hypokalemia

d. Hypophosphatemia







Answers with Rationale:

Refeeding syndrome occurs in the setting of chronic malnutrition when a patient is refed with aggressive amounts of dextrose. Although more likely to occur with parenteral feeding, it has also been reported with enteral and oral feedings. In extreme cases, it can be associated with pulmonary and cardiac failure and central nervous system involvement which can be life threatening.

Answer a is correct. Although hypophosphatemia is the hallmark electrolyte abnormality of refeeding syndrome, hypokalemia and hypomagnesemia may also occur as outlined under answer d below.

Answer b is incorrect. Although hypercalcemia is common in patients with cancer, it is not the hallmark of refeeding syndrome.

Answer c is correct.  Although hypophosphatemia is the hallmark electrolyte abnormality of refeeding syndrome, hypokalemia and hypomagnesemia may also occur as outlined under answer d below.

Answer d is correct. With carbohydrate refeeding, phosphorus, magnesium, and potassium, which are primarily intracellular electrolytes, are forced intracellularly by the action of insulin. This leads to lower levels of these electrolytes in the extracellular space, including the blood, where levels are routinely measured. Therefore, hypophosphatemia, hypomagnesemia, and hypokalemia are expected with refeeding. Hypophosphatemia is the hallmark electrolyte abnormality. Phosphorus is important in diaphragm function and in energy metabolism as a component of adenosine triphosphate (ATP). Thus hypophosphatemia can contribute to respiratory failure in severe refeeding syndrome.

See everyone next week!

Dr. B

Christopher M. Bland

Clinical Professor, University of Georgia College of Pharmacy

Dr. Christopher M. Bland is a Clinical Professor at the University of Georgia College of Pharmacy at the Southeast GA campus in Savannah, GA. Dr. Bland has over 20 years of academic and clinical experience in a number of clinical areas. He is a Fellow of both the Infectious Diseases Society of America as well as the American College of Clinical Pharmacy. He is co-founder of the Southeastern Research Group Endeavor, SERGE-45, with over 80 practitioners across 14 states involved. Dr. Bland serves as Associate Editor for the NAPLEX Review Guide 4th edition as well as Editor-In-Chief for the Question of the Week. He has provided live, interactive reviews for more than 10 Colleges/Schools of Pharmacy over the course of his career.