Euthyroid Sick Syndrome (Functional Hypothyroidism) in Patients With COVID-19 Runmei Zou,1,†Chenfang Wu,2,†Siye Zhang,2Guyi Wang,2Quan Zhang,3Bo Yu,2Ying Wu,2Haiyun Dong,2Guobao Wu,2Shangjie Wu,4 and Yanjun Zhong2,* https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575767/ Published online 2020 Oct 7. doi: 10.3389/fendo.2020.566439PMCID: PMC7575767PMID: 33117282 “Euthyroid Sick Syndrome” (ESS) is Functional Hypothyroidism (see my post on thyroid). It is the physiologic adaptation and pathologic response to stress, particularly to the stress of acute disease. It can be defined as a state in which T3 and T4 are low, without increased TSH.In the pathophysiological process of ESS, type III deiodinase is activated and type I is suppressed, so there is preferential conversion of T4…