This paper demonstrates how TSH changes lag well behind changes in FT4/3 levels. The longer the dwell time of a particular set of FT4 and FT3 concentrations the longer the lag in TSH response. Useful to provide evidence that TSH is not a credible test if applied wrongly at the wrong time.
A Review of the Phenomenon of Hysteresis in the Hypothalamus–Pituitary–Thyroid Axis
Melvin Khee-Shing Leow
Published on 14 June 2016
Front. Endocrinol. doi: 10.3389/fendo.2016.00064