NTI Syndrome

This episode demystifies non-thyroidal illness syndrome, breaking down the dramatic shifts in thyroid hormone economy that occur during systemic illness. We discuss the acute phase, where suppressed type one deiodinase and upregulated type three deiodinase cause a rapid drop in triiodothyronine and a rise in reverse triiodothyronine. Finally, we examine how chronic illness triggers central hypothalamic-pituitary-thyroid axis suppression, keeping thyroid stimulating hormone paradoxically normal or low, and outline the distinct hormonal rebound seen during recovery.