Urinary excretion of D-serine in human: comparison of different ages and species

Biol Pharm Bull. 1998 Feb;21(2):156-62. doi: 10.1248/bpb.21.156.


The urinary excretion of D-serine (D-Ser) in human, rat and dog of various ages was studied. Great amounts of D-Ser were consistently excreted in human urine throughout life. No age-dependent changes were observed in urinary D-Ser/total-Ser ratios from the newborn to the aged. D-Ser/creatinine ratios in adult human urine were found to be relatively constant in individuals. The constant excretion of D-Ser in human urine was confirmed by analyzing the consecutive 24 h urine of three volunteers. High concentrations of D-Ser and D-alanine (D-Ala) were found in adult dog urine. The urinary D-Ser concentration was high in young rats at unweaned and weaned periods, and then declined with increasing age. In contrast, the urinary D-Ala concentration was very low in suckling rats, and increased rapidly after the weaned state and then declined with increasing age. The species- and age-related excretion of D-Ser in mammalian urine is considered to be due to the differences in the renal handing of D-Ser, because plasma D-Ser concentrations among the groups were not so different. Although free D-Ser has been detected in animal foods and human colostrum, the amount is insufficient to explain the concentration of D-Ser found in urine. These results indicate that urinary D-Ser in mammals may be mainly of endogenous origin.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aging / urine*
  • Alanine / analysis
  • Animal Feed / analysis
  • Animals
  • Child
  • Chromatography, High Pressure Liquid
  • Colostrum / chemistry
  • Dogs
  • Humans
  • Infant
  • Male
  • Rats
  • Rats, Wistar
  • Serine / blood
  • Serine / urine*


  • Serine
  • Alanine