Don't know if this has been shared, very interesting.
nahypothyroidism.org/deiodi...
"In such conditions, tissue levels of T3 are shown to drop dramatically out of proportion with serum T3 levels (8,9,100-103,174-176). While serum T3 levels may drop by 30%, which is significant but still may be in the so-called “normal range,” tissue T3 may drop by 70-80%, resulting in profound cellular hypothyroidism with normal serum TSH, T4, and T3 levels (8,11,100-103,146,174). "