part of part of has part has part characteristic of has modifier trans-4-hydroxy-L-proline Azotemia Hydroxyprolinemia Hydroxyproline is an imino acid normally present in human plasma and is derived primarily from endogenous collagen turnover and the breakdown of dietary collagen. Hyperhydroxyprolinemic patients show hydroxyproline blood levels between 150 and 500 micromole per liter. Normal levels are around 10-20 micromole per liter. Abnormal circulating proline concentration Abnormal circulating monocarboxylic acid concentration Abnormal circulating non-proteinogenic amino acid concentration abnormal increased amount blood