Switching the Regimen That Built Him
A 22-year-old on the testosterone that carried him through a delayed puberty now asking to come off it — to start a much slower, less certain regimen aimed at something testosterone itself can't give him.
Simon O. was diagnosed with Kallmann syndrome at sixteen, after his failure to enter puberty alongside his classmates and an accompanying inability to smell prompted a workup that confirmed congenital hypogonadotropic hypogonadism with anosmia, the defining combination of the condition. He has been on testosterone replacement since then, started specifically for pubertal induction and continued since for maintenance, and describes the six years since as the period his body and his sense of himself as an adult man actually took shape — a detail that matters to how he is approaching today's conversation, since what is being proposed is coming off the regimen that got him there.
He is now in a serious relationship and has told his endocrinologist directly that he wants to have biological children eventually, which raises a genuine conflict with his current, working regimen: exogenous testosterone, while correcting his symptoms and supporting normal bone and metabolic health, provides no signal to his testes to produce sperm, since his underlying condition is a failure of hypothalamic GnRH secretion, not testicular failure itself — his testes, properly stimulated, retain real capacity to respond. Achieving that stimulation requires switching from testosterone to a gonadotropin regimen, typically hCG first to mimic LH and stimulate testicular testosterone production and some testicular growth, with FSH added later if spermatogenesis doesn't establish on hCG alone, a sequence that can take many months to begin producing sperm and, in a meaningful share of men, considerably longer than that.
Simon's own case history includes one relevant detail worth naming directly: he did not have cryptorchidism as an infant, which in published series of men with congenital hypogonadotropic hypogonadism is associated with meaningfully better odds of successful spermatogenesis induction than in men who did, since undescended testes at birth reflect a longer prenatal period without the gonadotropin exposure that normally drives early testicular development. That detail favors him relative to some men with his condition, though it doesn't guarantee success, and the transition itself is not free of real, near-term cost: coming off testosterone and waiting for gonadotropin therapy to establish its own effect means passing back through a genuine washout period, during which his hypogonadal symptoms — the fatigue, low mood, and low libido that testosterone has kept controlled for six years — are likely to recur to some degree before hCG's own effect takes over.
Established follow-up, planning a transition he's asked for
Given that he's told us directly he wants biological children, I'd start the transition to gonadotropin therapy now rather than later. The hCG-then-FSH sequence can take many months to begin producing sperm at all, and in a meaningful share of men longer than that — every month spent on the current testosterone regimen instead is a month added to an already long timeline, not a neutral delay.
I'm not arguing against the transition — he's asked for it directly, and it's the right goal. What I want made explicit before he commits is the real, near-term cost: coming off a testosterone regimen that's kept him stable for six years means passing back through a genuine washout period, and his hypogonadal symptoms, the fatigue and low mood he's lived without for years now, are likely to recur to some degree while hCG's own effect ramps up. That's not a reason not to do this — it's a real cost he deserves to walk into with full information, not discover partway through.
Starting sooner does shorten the overall timeline to any spermatogenesis — I'm not disputing that math. I just don't want the timeline urgency to crowd out an honest conversation about what the transition itself will feel like for him.
One detail worth putting in front of him directly: he never had cryptorchidism as an infant, which in published series of men with his condition is associated with meaningfully better odds of successful induction than in men who did. That's genuinely favorable, though not a guarantee. I'd start hCG now, counsel him honestly on both the timeline and the washout-period symptoms, and add FSH later specifically if semen analysis at six months shows inadequate spermatogenesis on hCG alone.
Agreed: hCG started today in place of his testosterone gel, with semen analysis at six months as the defined decision point for adding FSH, and an explicit, documented conversation about the washout-period symptom recurrence he should expect before it happens rather than after.
The urologist's prognostic detail — his favorable, no-cryptorchidism history — was offered to inform Simon's own expectations honestly, not to promise a specific outcome; all three voices were careful, in what was actually said to him, not to convert a favorable factor into a guarantee neither the literature nor his own case supports.