If one is Primary Hypogonadism there will be no response from Exogenous hCG resulting in a higher turnover rate to estrodiol, high doses (1000+ ius) over long periods of time can desensitize the Leydig's Hormone causing Primary Hypogonadism,possibly causing high levels of ITT-A (Intratesticular Testosterone Aromatase)
If one is Secondary Hypogonadal hCG stimulates several hormonal responses beyond mimicing LH
Serum 17-hydroxyprogesterone strongly correlates with intratesticular testosterone in gonadotropin-suppressed normal men receiving various dosages of human chorionic gonadotropin
In respect to the sulfate hormones ~17- hydroxyprogesterone , can in some cases metabolize to 17- hydoxypregenolone > neurosteroid.
Pregenolone is considered a "Feel good Hormone", this may explain why some a better sense of well being while supplementing with hCG
There are several metabolizing pathways hormones follow, there are several sites to find this, easy Google.
When speaking of HRT protocol ,not to be confused with TRT( specific to Testosterone replacement), Think global of the endocrine system as a whole.
Hormones work in harmony when proper modulation is implemented.
With hCG one needs to find the right dosing protocol in respect to blood work, some may need as little as 100ius EOD to 500 ius EOD or any variable in between ; 150,200,250 ect.
I'll leave it at that as I gotta get back to work, here's a good read also
Dr John Crisler on HCG for Symptoms of Low Testosterone