Free 4-hydroxyproline content in serum of bedridden aged people is elevated due to fracture

Hydroxyproline (Hyp) content in biological fluids is used as a parameter of collagen catabolism, especially bone resorption. In this paper,we examined the relationship between aging and serum free 4-Hyp and proline (Pro) cont ent using a newly introduced analytical technique which is chemiluminescenc e determination with electrogenerated tris (2,2'-bipyridine) ruthenium(III) . Serum was collected from 50 bedridden aged people and 131 normal subjects living in Yamato-son, Amamioshima, Kagoshima. In the free 4-Hyp content of normal serum, the change in females is more gentle than that males with ag ing. The free 4-Hyp content of bedridden aged serum is significantly (p < 0 .05) elevated compared to normal aged serum. Bedridden aged females and mal es also show levels significantly (p < 0.05) elevated in comparison to norm al. These changes are due to bone resorption based on bedridden patients' a trophy In bedridden aged people, free 4-Hyp of those with a fracture was si gnificantly (p < 0.05) elevated than in people without a fracture. No relat ionship between low bone density and high free 4-Hyp in serum was observed. It seems that bone resorption or bedridden atrophy may be enhanced in bedr idden aged people by a fracture. In free Pro content in serum, no significa nt change was observed. These results show that the free 4-Hyp content in s erum is useful in the clinical or biological inspection of bone resorption, especially in aged people.