Abstract: Objective　To explore the clinical characteristics of hyperprolinemia. Method　The clinical data of children suspected of hyperprolinemia from November 2013 to April 2019 were analyzed retrospectively. Results　A total of 15 children (5 boys and 10 girls) were found at least twice to have blood proline levels >400 μmol/L. In 3 patients diagnosed with hyperprolinemia by genetic testing, two were neonates and one was an 11-year-old female. Twelve cases were suspected of hyperprolinemia. In 6 cases, proline gradually decreased to the normal range during follow-up at 3-6 months after birth, and in another 6 cases, follow-up was interrupted and genetic testing was refused. Conclusions　For those whose proline are ≥1000 mol/L or at 400~1000 mol/L at the initial screening but still remains high at the age of 6 months, genetic testing should be improved as soon as possible, and follow-up should be strengthened.

Key words: 　hyperprolinemia;　proline;　tandem mass spectrometry;　proline oxidase;　P5C dehydrogenase