[Age-related characteristics of urinary excretion of oxyproline].

Age-dependent alterations in excretion of hydroxyproline were studied in 62 healthy persons (3-78 years old) by means of analysis of the morning portion of urine after gel filtration on Sephadex G-10. With ageing the following patterns were decreased: content of total hydroxyproline (r = -0.78; P less than 0.001), the ratio hydroxyproline/creatinine (r = -0.80, P less than 0.001) and content of hydroxyproline in peptide fraction with MW greater than 700-1000 (r = -0.50; P less than 0.001). The reverse correlation was found between the contents of total and free hydroxyproline (r = -0.45; P less than 0.001) but total content of hydroxyproline correlated directly with its content in the peptide fraction (r = 0.92; P less than 0.001). At the same time, reverse correlation was observed between the contents of free hydroxyproline and of the peptide-bound amino acid (r = -0.58; P less than 0.001). Approximate ranges of normal excretion of hydroxyproline with urine were calculated in various age groups.