Blood urea nitrogen-guided protein dosage adjustment helps reduce azotemia and functional prognosis deterioration induced by high protein intake in neurocritical patients: A retrospective cohort study

Abstract

The optimal protein dosage for neurocritical patients remains uncertain. We hypothesized that higher protein dosage increases azotemia risk and worsens prognosis, and that baseline BUN can guide protein dosage adjustments. In this single-center, retrospective cohort study, we included 327 neurocritical patients aged 18 or older admitted between July 2018 and June 2023 (BMI: 18.5-30 kg/m²). Daily protein intake from all sources was calculated. The primary outcome was azotemia incidence, and secondary outcomes included 30-day functional prognosis (mRS >3). Patients were categorized by protein intake: <0.8 g/kg/d, 0.8–1.3 g/kg/d, and >1.3 g/kg/d. Azotemia incidence was lower in the <0.8 g/kg/d group compared to the >1.3 g/kg/d group (21.9 vs. 45.7%, adjusted p = 0.002), with a significant correlation after adjusting for confounders. Among patients with an APACHE II score <15, the <0.8 g/kg/d group had lower azotemia rates and better prognosis. For those with a score ≥15, the >1.3 g/kg/d group had higher azotemia rates and worse prognosis. A U-shaped relationship between BUN and 30-day prognosis was observed in the <0.8 g/kg/d group. For BUN <4.3 mmol/L, protein intake of 0.8–1.3 g/kg/d improved outcomes, whereas for BUN >4.3 mmol/L, intake <0.8 g/kg/d was beneficial. The research demonstrates that excessive protein intake is associated with increased azotemia risk and worse outcomes. Baseline BUN may help inform protein dosage selection in neurocritical care, though its generalizability requires validation in multicenter prospective studies.