Abstract:Ohjective 'To comapre and analyze the differences and commonalities of expression profiles of serum exosomal microRNA between patients with thyroid nolules and healthy persons at different iodine levels , and then providle evidence for sereening early diag-nostic markers of thyroid nodules at different iodline levels. MethodsThe peripheral blood samples from 10 patients with thyroid nod-ules and healthy volunteers at different iodine levels were collected.'Tlheir serum iodline levels were measured by the arsenic cerium catalytic spectrophotometry.Serum exosomal microRNA were extracted and the expression levels of microRNA were deternined by thehigh-throughput sequencing technology.The differential targret genes were predicted and further performedl Cene ontology ( CO) analysisand Kyoto Encyclopedia of Cenes and Cenomes (KECC) analysis.Results Compared with healthy volunteers , there were 6 downreg-ulated miRNAs in the patients with thyrwoid nodules at different iodline levels，namely miR-324-5p，miR-6511b-3p，miR-903,miR-550a-3p,miR-5001-3p, and miR-3688-3p. Differentially expressed exosomal microRNA could regulate the MAPK signaling path-way ， PIBK-AKT' signaling pathway , VECF signaling pathway , and NF -kB signaling pathway.Conclusion Six differentially expressedmicroRNAs is identifiedl， which may serve as biological markers for the early diagnosis of thyroid nodules at diflerent iodine levels.