Effect of elemental diet on albumin and urea synthesis: comparison with partially hydrolyzed protein diet

Enhanced nitrogen utilization occurs when adults with gastrointestinal disease are fed partially hydrolyzed proteins instead of isonitrogenous, isocaloric crystalline amino acids. A controlled trial was conducted to determine if this difference was also seen in malnourished stressed cancer patients and to gain an understanding of the underlying mechanism. Sixteen malnourished patients with head and neck cancer were prospectively randomized to either crystalline amino acid-glucose (CAA-G) or partially hydrolyzed protein-glucose (PHP-G) diets. Patients were fed via an enteral tube for 10 days starting on the second postoperative day. Blood SMA-6 and amino acid levels were measured on Days 1 and 10. Daily calorie counts and fluid balance were obtained. Daily 24-hr urine and stools were analyzed for total N during the last 5 days of the study period. The daily positive N balance with both diets was the same (CAA-G = +7.8 +/- 0.8 vs PHP-G = +8.2 +/- 1.0 g; mean +/- SE) and 3-methylhistidine:creatinine ratio did not differ. Patients on PHP-G diet gained significantly more weight (+0.5 vs - 1.5 kg; P less than 0.01) and had significantly higher serum albumin (3.2 +/- 0.2 vs 2.8 +/- 0.1 g/dl; P = 0.5) by the end of the 10th study day. Weight changes were not due to fluid retention: serum Na+, K+, creatinine and mean fluid intake for the two groups remained the same during the study period. A significantly greater rise in BUN occurred on the CAA-G diet (from 9.2 +/- 1.7 to 15.4 +/- 1.4 mg/dl; P less than 0.05) while BUN remained unchanged on the PHP-G diet.(ABSTRACT TRUNCATED AT 250 WORDS)