Increase in Urinary Desmosine and Pyridinoline During Postpartum Involution of the Uterus in Humans

Abstract

Abstract

One of the most rapid changes in collagen and elastin content of a tissue occurs in the uterus following postpartum involution. We measured the urinary excretion of specific amino acid markers for mature elastin (desmosine [DES] and isodesmosine [IDES]) and fibrillar collagen (hydroxylysyl pyridinoline [HP] and lysyl pyridinoline [LP]) before and after parturition in three gravid subjects. For that purpose, we used an isotope dilution method coupled with gel filtration and HPLC. The highest DES values were found 2–5 weeks postpartum and were 18–45 μg/g creatinine or two to six times those found for healthy neversmoking nongravid females (7.7 ± 0.3 μg/g creatinine, mean ± SE). The highest levels of urinary HP for each subject were found 2–3 weeks after parturition and were 115–607 nmol/mmol creatinine or 4–21 times those found for healthy neversmoking nongravid females (28.1 ± 1.3 nmol/mmol creatinine). For the gravid subjects as a group and also for each subject, the mean values for urinary DES, IDES, HP, and HP/LP during the first 6 weeks postpartum were significantly greater than the mean baseline values beginning 27 weeks postpartum. For the gravid subjects as a group, the mean value for urinary HP/LP during the first 6 weeks postpartum was significantly greater than the value during the 20 weeks preceding parturition. This suggested that the tissue(s) of origin of the excess HP, during the 6 weeks following parturition, was not bony and was consistent with a uterine origin.