NAPLEX Question of the Week: Parenteral Nutrition
Parenteral nutrition is part of a pharmacist's daily practice within a number of settings, especially acute care and home care. Today's question focuses on the calculation aspect of parenteral nutrition.
A 55 yo M in the ICU is receiving TPN daily with 400 g of dextrose, 100 g of amino acids, and 250 ml of 10% lipids. How many non-protein calories is the patient receiving from the TPN?
A. 1510 kcal
B. 1635 kcal
C. 1740 kcal
D. 2035 kcal
Answer and Rationale:
The correct answer is B.
Calculations involving parenteral nutrition are a common part of pharmacy practice. Many pharmacists, especially critical care pharmacists, perform these calculations on a daily basis and are relied upon to determine appropriate nutritional requirements within parenteral nutrition for patients requiring these therapies.
- The question is asking for non-protein calories so calories from amino acids do not need to be calculated.This makes answer D incorrect as this would be TOTAL calories. Don't miss a question because you assumed the right question...read thoroughly and accurately!
- Calories from dextrose:
- Dextrose provides 3.4 kcal/g
- 400 g X 3.4 kcal/g = 1360 kcal
- Calories from lipids:
- 10% of a lipid solution provides 1.1 kcal/ml
- 250 mls X 1.1 kcal/ml = 275 kcal
- 1360 kcal + 275 kcal = 1635 kcal which is the correct answer.
For more information on parenteral nutrition, please see our chapter in the NAPLEX 3rd edition: