Age‐related variations in prostaglandin E‐major urinary metabolite values in Japanese children

BACKGROUND: Prostaglandin E-major urinary metabolite (PGE-MUM) is an emerging noninvasive biomarker used to evaluate clinical and endoscopic activity in patients with inflammatory bowel disease. Previous studies have shown that PGE-MUM values correlate with colonic inflammation in pediatric ulcerative colitis; however, reference values for children without inflammation have not been defined yet. This study aimed to determine the normal reference values of PGE-MUM in healthy pediatric subjects without inflammatory conditions. METHODS: Between December 2018 and January 2022, we prospectively enrolled 221 participants (cross-sectional study, aged 0-15 years) who were undergoing growth hormone stimulation testing for diagnostic purposes and exhibited no symptoms of inflammation or elevated C-reactive protein levels at a single pediatric center in Japan. PGE-MUM values were measured using a chemiluminescent enzyme immunoassay and assessed for age- and sex-related differences. RESULTS: A total of 218 participants were included in the analysis. Based on age, the participants were classified as young children (2-6 years, n = 147) and older children (7-14 years, n = 66); the reference ranges for the two groups were identified as 18.4-58.7 μg/g·Cr and 12.4-50.3 μg/g·Cr, respectively. The PGE-MUM values tended to decrease with increasing age; however, no significant sex-related differences were observed (median 29.1 μg/g·Cr for boys versus 30.4 μg/g·Cr for girls). CONCLUSIONS: Healthy pediatric subjects generally have higher PGE-MUM values than healthy adults, with particularly elevated values in young children (2-6 years). These observations suggest that age-related variability must be taken into account when using PGE-MUM as a biomarker in young children with ulcerative colitis.