Background:
protein restriction is the mainstay of dietary management of chronic
kidney disease. Aim: to assess the usefulness of urine
urea nitrogen measurement as a marker of
protein restriction. Methods: healthy young participants were randomly divided in two groups. During 14 days, one group received a diet containing 30 kcal/kg
body weight and 1
g protein/kg
body weight and the other group received a diet with the same amount of calories and 0.6 g/kg of
proteins. At baseline, seven days and 14 days, 24 h dietary recalls were answered by the participants. They collected 24 hour urine and provided spot urine samples at baseline and at the end of the intervention, to measure
creatinine and
urea nitrogen. Results: forty-one participants aged 29 ± 5 years completed the follow-up. According to 24h dietary recalls, the group receiving 0.6 g/kg
protein reduced significantly the
protein intake during the intervention from 0.88 ± 0.06 to 0.59 ± 0.05 g/kg/day. A significant reduction in 24 h
urea nitrogen excretion was also observed in this group. In the group receiving 1 g/kg of
protein, no significant changes in 24 h
urea nitrogen excretion were observed. Among all participants, the odds ratio of observing a reduction in
protein intake in the dietary survey was 5.75 (95% confidence intervals 1.29-25.55, p = 0.02), when a reduction in 24 h
urea nitrogen excretion corrected by
creatinine was observed. No changes were observed in
urea nitrogen excretion in spot urine samples. Conclusions: repeated
urea nitrogen excretion measured in 24 h urine samples can be a reliable
indicator of
dietary protein restriction.