Some docs test pregnenolone and DHEA or DHEA-s levels.
Some folks respond to orals of these, some so not. I take 100mg of each every day and my levels did not go up.
The mitochondria inside your cells produce pregnenolone. That is the raw material for production of DHEA which is the raw material for production of testosterone, estrogen, progesterone.
I would say that DHEA is more important. And if pregnenolone is low and DHEA normal, I can’t see the point of taking pregnenolone at all. If the doc did not do testing for these and wants you to purchase from him, I would be worried. And you can probably get better value elsewhere in any case.