Background & aims: Nitrogen balance (NB) is an important indicator of protein utilization in the body, and a positive NB is essential for maintaining and improving nutritional status. However, information is lacking on the target values of the energy and protein levels required to maintain positive NB in cancer patients. This study aimed to verify the energy and protein requirements for positive NB in preoperative esophageal cancer patients.
Methods: This study included patients for esophageal cancer surgery who were admitted for radical surgery. Urine urea nitrogen (UUN) levels were measured based on 24-h urine storage. Energy and protein intakes were calculated from the dietary intake during hospitalization and the amount administered from enteral and parenteral nutrition. The characteristics of the positive and negative NB groups were compared, and patients' characteristics related to UUN excretion were analyzed.
Results: Seventy-nine patients with esophageal cancer were included, and 46% of patients were negative NB. All patients with energy intake ≥30 kcal/kg/day and protein intake ≥1.3 g/kg/day had positive NB. Whereas, in the group with energy intake ≥30 kcal/kg/day and protein intake <1.3 g/kg/day, 67% of patients were positive NB. There was a significant positive relation between UUN excretion and retinol-binding protein in multiple regression analyses adjusted for several patients' characteristics (β = 0.28, p = 0.048).
Conclusion: In preoperative esophageal cancer patients, 30 kcal/kg/day of energy and 1.3 g/kg/day of protein were the guideline values for positive NB. Good short-term nutritional status was a factor associated with increased UUN excretion.
Keywords: Esophagectomy; nitrogen balance; nutritional requirements; nutritional support.