Influence of enteric nutrition on blood urea nitrogen (BUN) in very old patients with chronic kidney disease (CKD)

The purpose was to check the influence of enteric nutrition on BUN in very elderly patients. Clinical data on patients in whom enteral feeding was initiated after a period of poor oral intake are presented. Patients with evidence of volume depletion, signs of gastrointestinal bleeding or medicines that might increase BUN were excluded. We evaluated 5 patients (mean age 90.6 ± 3 years) who were admitted to geriatric department. Mean plasma creatinine concentration was 1.17 ± 0.34 mg/dl, but mean estimated glomerular filtration rate (eGFR) was 41.6 ± 17 ml/min/1.73 m2. Enteral nutrition was administered at a dose of mean 1580 ± 53 ml/day at mean duration of 9 ± 4 days. Mean BUN was 52 ± 30 mg/dl at baseline, increases to 109 ± 9.4 mg/dl after initiation of feeding and decreased to 82 ± 1.1 mg/dl with reduction of dose of enteral nutrition. Our conclusion was that initiation of enteral feeding may induce a large accumulation of nitrogen waste products in elderly patients in whom serum creatinine is an unreliable indicator of kidney function. High protein intake should be considered in differential diagnosis of disproportionate high increment of BUN.