I dug into this some and found this
Why T Levels Might Appear Normal:
In some cases, even with Lupron's effectiveness in lowering testosterone, the initial T levels might still be within the normal range. This is because some testosterone comes from sources other than the testicles, and Lupron primarily targets testicular testosterone production.
Lupron, a gonadotropin-releasing hormone (GnRH) agonist, suppresses testosterone production, leading to a decrease in PSA levels, even if T levels remain within the normal range. This occurs because PSA, a marker for prostate cancer, is influenced by testosterone. While T levels might remain in the normal range, Lupron effectively reduces the stimulation of prostate cells that produce PSA, resulting in a lower PSA count.