Determinants of urinary nitrogen excretion in burned patients.

A retrospective study of urinary urea excretion has been performed in 91 burned patients. Maximum mean excretion occurred between days 5 and 8 after injury. The rate of excretion during this peak period correlated significantly with the sex and age of the patient as well as the burn size. It is suggested that peak nitrogen excretion may be more accurately predicted if all three variables are considered. However, the wide variation seen in patient response and differences in clinical management mean that regular measurement of urinary urea excretion still provides the most reliable guide to dietary protein requirements after a burn.