5-Hydroxyindole acetic excretion in newborns, infants and children.

The 5-hydroxyindole acetic acid excretion of healthy prematures, term newborns, infants, and children up to 15 years of age was investigated. Comparison of the results with healthy adult values suggests that more exact information can be obtained on excretion values of children if they are calculated for bodyweight. The results obtained in the different age groups point to an increased activity of serotonin metabolism in newborns, infants and children. During the important phases of somatic and psychomotor development an increased urinary output of 5-hydroxyindole acetic acid was found as compared with adult values.