Mathes M, et al. - In this randomized controlled trial, the researchers intended to evaluate the impact of different levels of enteral protein on plasma and urinary urea concentrations and determines whether the urinary urea-creatinine ratio provides reliable information about the protein status of preterm infants. This trial was conducted on 60 preterm infants (birthweight < 1500 g; gestational age < 32 weeks). They suggested that the urinary urea-creatinine-ratio, just like plasma urea concentrations, could help to estimate actual protein supply, absorption and oxidation in preterm infants and, additionally, can be determined non-invasively.