The Marshall protocol perspective is that 1,25-D spreads from the site of the inflammation (where it is acting as a cytokine) through the bloodstream (acting as a hormone)... 1,25-D directly controls the Parathyroid Hormone (PTH) and thence the Thyroid hormones as well as a number of other metabolic pathways, so it is pretty powerful feedback to the body systems, and when the bacteria interrupt that feedback path everything goes unstable.

I do know that when I corrected my 1,25-D, my usual thyroid supplement made me feel wired. I have not taken it since. Normally, missing a dose I would feel dead.