Elevated urinary collagen degradation products Elevated urine pyridinoline level 2021-01-02T13:31:16Z Elevated urine hydroxylysyl-pyridinoline level The urinary cross-links lysyl-pyridinoline (LP, or deoxypyridinoline DPD) and hydroxylysyl-pyridinoline (HP, or pyridinoline PYD) are biochemical markers of osteoclastic bone resorption and collagen degradation. Pyridinolines are formed during fibril formation of type I and type II collagen in the extracellular matrix. Some lysyl- and hydroxylysyl-residues in distinct positions in the collagen triple-helix and in the telopeptides of the tropocollagen are oxidized by lysyl oxidase. Subsequently three of these residues are covalently linked thereby interconnecting tropocollagen molecules and stabilizing the collagen matrix. When bone collagen is degraded, pyridinolines remain as stable degradation products and are secreted with the urine. An increased amount of pyridinoline in the urine.