Impact of renal function and protein intake on blood urea nitrogen in preterm infants in the first 3 weeks of life

OBJECTIVE: To examine the relationship between blood urea nitrogen (BUN) during the first 3 weeks of life and protein intake and creatinine (Cr) and to quantify the effect of protein intake on postnatal growth in preterm infants. STUDY DESIGN: This is a 4-year, single-center, retrospective cohort study. We used multivariable linear regression models to examine the relationships between mean weekly BUN and protein intake adjusted for mean weekly Cr and potential confounders. We used additional regression models to examine the effect of protein intake on growth during this period. RESULT: Overall, 249 infants met study criteria. As protein intake increased over the first 3 weeks of life, both BUN and Cr decreased significantly. Linear regression models showed protein intake and Cr were each significantly associated with mean BUN for each study week. CONCLUSION: Protein intake and Cr were each significantly associated with BUN. Significant amelioration of growth failure was seen with higher protein intake.