Objective: To explore the effect of birth weight on urea kinetics in young healthy children.
Design: Observational study.
Setting: Tertiary center for treatment of malnutrition.
Subjects: A total of 17 male children, 6-24 months old, who had recovered from malnutrition.
Interventions: Urea kinetics were measured using stable isotope methodology with [(15)N(15)N]-urea over 36 h.
Results: Birth weight was negatively related to urea hydrolysis after controlling for the intake of protein (adjusted R (2 ) = 0.91, P = 0.001) and separately for energy intake (adjusted R (2) = 0.95, P = 0.001), age (adjusted R (2) = 0.90, P = 0.001) and rate of weight gain (adjusted R (2) = 0.91, P = 0.001). There was a tendency for higher urea production in the children with lower birth weight after controlling for nitrogen intake (adjusted R (2) = 0.93, P = 0.099), and separately for age (adjusted R (2) = 0.94, P = 0.06) and rate of weight gain (adjusted (R (2) = 0.92, P = 0.096). Urea excretion was not significantly related to birth weight.
Conclusions: The salvaging of urea nitrogen following urea hydrolysis contributed significantly more to the nitrogen economy in children with lower birth weight compared to those with higher birth weight. This may be as a result of reductive adaptation in the children with lower birth weight as a consequence of inappropriate prenatal nutrition and growth.