This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Nitrogen to caloric ratio in total parenteral nutrition is: 
Select and explain. 
A. 1 gm of N2: 150 non protein calories, B. 1 gm of N2: 100 non protein calories, C. 1.25 gm of N2: 100 non protein calories, D. 1.25 gm of K: 150 non protein calories
A: 1 gm of N2: 150 non protein calories
Answer: A: 1 gm of N2: 150 non protein calories 
Explanation: Parenteral formulas usually deliver 75-150 non protein carbohydrate kcal per gram of nitrogen infused, a ratio that maximizes carbohydrate and protein assimilation and minimizes metabolic complications (aminoaciduria, hyperglycemia, and hepatic glycogenesis). Ref: Barbour J.R., Barbour E.F., Herrmann V.M. (2010). Chapter 10. Surgical Metabolism & Nutrition. In G.M. Dohey (Ed), CURRENT Diagnosis & Treatment: Surgery, 13e.