Indicator Explainer
Hydroxyproline
A nonessential amino acid derivative formed during post-translational protein modification through hydroxylation of the amino acid proline by the enzyme prolyl hydroxylase which requires vitamin C as a co-factor. Hydroxyproline is a major component of the protein collagen and plays a key role in the stability of the collagen triple helix. It can be used as an indicator to determine the amount of collagen. Increased hydroxyproline levels in the urine and/or serum are normally associated with degradation of connective tissue. Vitamin C deficiency decreases the conversion of proline to hydroxyproline, which leads to reduced collagen stability.
This page explains what the indicator is and how results are interpreted in general terms. Reference ranges depend on the laboratory, the method, and your own situation — no single “normal value” applies to everyone. This page is health information, not a diagnosis. For symptoms, treatment, or urgent concerns, contact a healthcare professional.
When it is tested
Source: National Cancer Institute, NCI Thesaurus 26.09d, C76144. NCI definition, reproduced without modification under CC BY 4.0. Source identity and definition checked automatically on 2026-10-20. No individual clinical interpretation or human reviewer is asserted.
Reading results
Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.