TPO and selenium deficiency: When there is selenium deficiency, disruption of the body's immune system, weakened antioxidant effect, and insufficient scavenging of free radicals lead to the destruction of thyroid follicular epithelial cells and the release of Tg and TPO into the circulation, which triggers an immune inflammatory response and a significant increase in the body's TPOAb and TGAb levels, thus inducing or aggravating CLT [23, 24].