Evaluation of urinary neopterin and biopterin levels in pediatric cancer patients

Objective: This study aimed to evaluate the performance of urinary pterin/creatinine ratios in distinguishing active disease from remission, viral infection, and healthy controls in childhood cancers, and to assess their association with disease activity, prognosis, and treatment response.Materials and Methods: A total of 193 age- and sex-matched children were included: 50 with active malignancy, 48 in remission, 51 with viral infection, and 44 healthy controls. Urinary concentrations of neopterin, biopterin, pterin, pterin-6-carboxylic acid, and isoxanthopterin were measured and normalized to creatinine.Results: All urinary pterin/creatinine ratios were higher in the active malignancy group than in healthy controls. 6PTC/CREA, PT/CREA and ISOX/CREA were the strongest discriminators between active malignancy and healthy controls. Most pterin/creatinine ratios differed significantly between groups. Ratios were higher in the active group than in remission; ISOX/CREA was the most distinctive marker between active and remission. NE/CREA and 6PTC/CREA showed significant differences between active and viral groups. NE/BIO was higher in healthy controls than in other groups. Pterin ratios remained elevated in the remission group compared to healthy controls, indicating they did not return to baseline. No differences were observed between hematological and solid tumors within the active group.Conclusion: Urinary pterin/creatinine ratios, particularly 6PTC/CREA, ISOX/CREA, and PT/CREA, provide high diagnostic value for distinguishing active disease from healthy controls. ISOX/CREA also offers moderate discrimination between active disease and remission, supporting pterin metabolites as promising biomarkers in pediatric malignancies.