Remembering that this is a linear relationship, you can stack two calculations at once and get a good result.
Your change in T dose is factor Y, could be 1.2 to increase by 20% or 0.8 to decrease by 20%
Your E2 lab is newE2
Old Adex dose is Adex-old-dose
Adex-new-dose = Adex-old-dose * Y * newE2 / 22pg/ml
or in this case
Adex-new-dose = Adex-old-dose * 0.8 * newE2 / 22pg/ml
Years ago I was increasing T and correcting E2 and stacked both calculation and next labs I was on target.