Blood urea nitrogen and serum bicarbonate in extremely low birth weight infants receiving higher protein intake in the first week after birth

Objective:to determine correlation between early protein administration and serum blood urea nitrogen (bun) or bicarbonate (hco3−) in extremely low birth weight (elbw) infants during the first week of life.study design:a retrospective review of 154 elbws was conducted. laboratory and nutritional data from postnatal days 1, 4 and 7 were collected. repeated measures models estimated the relationship of protein intake with bun and hco3− in the first week of life.result:in total, 359 separate bun and hco3− values were analyzed. each gram per kilogram of protein administered was associated with an increase in mean bun of 3.3 mg/dl. this effect decreased daily by 2.1 mg/dl. each gram per kilogram of protein administered was associated with a decrease in mean hco3− by 0.9 mmol/l.conclusion:the association between protein load and bun is positive but decreasing over time. protein is associated with a clinically insignificant decrease in hco3−. concerns regarding metabolic derangement from early protein administration in elbws are unwarranted.