Urinary excretion of collagen metabolites in protein malnutrition

The effect of protein deficiency on the urinary excretion of hydroxyproline (total, nondialysable, dialysable and free fractions) and hydroxylysyl glycosides (glucosyl-galactosyl-hydroxylysine, glc-gal-hyl and galactosyl-hydroxylsine, gal-hyl) was investigated in female albino rats. In comparison to controls, the protein deficient animals were found to excrete significantly decreased amounts of urinary hydroxyproline fractions from the 7th day onwards. The excretion of total hydroxylysyl glycosides in urine parallels the excretion of hydroxyproline. The urinary output of both glc-gal-hyl and gal-hyl was also appreciably lower in deficient animals. The normal ratio of glc-gal-hyl/gal-hyl found in the urine of protein deficient animals suggests that there is a similar decreased turnover of collagen in both bone and skin.