The age dependency of the creatinine-related concentration of ribonucleosides in human urine.

We investigated the urinary excretion of ribonucleosides and an unidentified substance in 345 healthy probands from the age of a few weeks to 40 years. The concentration of ribonucleosides, related to the corresponding concentration of creatinine, decreases until nearly 20 years and remains constant between 20 and 40 years. The polynomial functions describing this dependency are presented. The biological significance of our findings is briefly discussed.