Evaluating serum S-Equol, indoxyl sulfate, and TMAO in predicting urinary stones in children: a prospective study

Gut microbiota is vital in maintaining health and has been implicated in urinary stone disease. Patients with and without stones have different microbial compositions. In this context, we assessed serum levels of S-equol, indoxyl sulfate (IS), and trimethylamine N-oxide (TMAO), which are metabolites thought to be associated with gut microbiota, and their prognostic values in predicting stone formation in children with urinary stone disease. The study population consisted of children aged between one month and 18 years with urinary stone disease. The patient group consisted of 44 children with urinary stone disease, and the control group consisted of 44 healthy children who were matched with the patient group in terms of age and gender. The study's primary outcomes were the differences between the groups in serum metabolite levels. Serum S-equol and TMAO levels were significantly lower in the patient group than in the control group. There was no significant difference between the groups in serum IS levels. There were also no significant correlations between serum metabolite levels and age in either group. Children with urinary stone disease had significantly lower serum S-equol and TMAO levels than healthy control subjects, suggesting a possible link between these metabolites and stone formation.