In 2017, the ESPEN guideline on surgery recommends 7-14 days of nutritional support prior to major GI surgery in malnourished patients who fulfil one of the following criteria: weight loss > 10–15% within 6 months; BMI < 18.5 kg/m2; Subjective Global Assessment (SGA) Grade C or NRS2002 > 5; and preoperative serum albumin < 30 g/L (with no evidence of hepatic or renal dysfunction) [9]. This evidence concerns the gene ALB and Abnormal renal physiology.