In a interview dr Michael Scally say: ..."The first phase of the HPTA protocol examines the functionality of the testicles by the direct action of hcg. hCG raises sex hormone levels directly through the stimulation of testis and secondarily decreases the production and level of the gonadotropin LH. The increase in serum testosterone with the hCG stimulation is useful in determining whether any primary testicular dysfunction is present. This initial value is a measure of the ability of the testicles to respond to stimulation from the hCG. Demonstration of HPTA functionality is by an adequate response of the testicles to raise the serum level of T well into the normal range. If this is observed the hCG is discontinued. The failure of the testes to respond to an hCG challenge is indicative of primary testicular failure."... And this article say: ...”hCG stimulates the Leydig cells in the testis to produce testosterone in hypogonadotropic hypogonadism patients without associated primary testicular disease. The dose of hCG should be adjusted until trough serum testosterone levels are restored to about the lower limit of the adult male range”... An update on male hypogonadism therapy So my conclusion was, if you get out of TRT, and after a while you start using HCG, and if during it, your testosterone get to a normal range (let's say 620 ngdl) you can say that for sure this person do not have primary hipogonadism, independent of HCG dosage used. Is that right?