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

ABSTRACT

OBJECTIVE: To determine correlation between early protein administration and serum blood urea nitrogen (BUN) or bicarbonate (HCO(3)(-)) 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 HCO(3)(-) in the first week of life. RESULT: In total, 359 separate BUN and HCO(3)(-) 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 HCO(3)(-) 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 HCO(3)(-). Concerns regarding metabolic derangement from early protein administration in ELBWs are unwarranted.