Andropause — late-onset hypogonadism, traditional TRT, and the HPG-axis-preserving peptide alternatives

"Andropause" is the colloquial frame for an endocrinological reality that the medical literature now calls late-onset hypogonadism. The distinction matters editorially. Menopause is a discrete event — cessation of ovulation, abrupt collapse of estradiol production, a clinically anchored before-and-after. The male trajectory has none of that structure. Serum testosterone declines gradually from roughly the third decade onward at a population-level rate of approximately 1–2% per year, with substantial inter-individual variability, large effects from comorbidity load (obesity, type 2 diabetes, sleep apnea, chronic illness), and no analogous binary cut-off (Wu et al., N Engl J Med 2010, 363:123–135). The result is a clinical syndrome that may or may not develop in any given man, may or may not be the cause of any given symptom cluster, and may or may not benefit from intervention — depending on confirmation of low testosterone, presence of consistent symptoms, and the goals of the man asking the question.

The Endocrine Society 2018 guideline (Bhasin et al., J Clin Endocrinol Metab 2018, 103:1715–1744) defines the modern diagnostic frame: hypogonadism requires both unequivocally and consistently low morning total testosterone and symptoms or signs consistent with testosterone deficiency. The harmonized reference range for healthy young men used by major US laboratories is 264–916 ng/dL (2.5th–97.5th percentiles); the older "300 ng/dL" threshold used in many clinical contexts is approximately the laboratory's lower bound for a single assay. The pivotal European Male Ageing Study (Wu et al., N Engl J Med 2010, 363:123–135; n=3,369) reported that only three sexual symptoms — poor morning erections, low libido, and erectile dysfunction — clustered reliably with low testosterone, and that the overall prevalence of symptom-and-biochemistry-confirmed late-onset hypogonadism in men aged 40–79 was approximately 2.1%. Fatigue, mood symptoms, and cognitive complaints, which dominate the cultural framing of "low T," did not separate cleanly along the testosterone gradient.

The peptide angle on andropause runs through a specific architectural feature of testosterone replacement therapy: exogenous testosterone, administered weekly by injection or daily by topical, shuts down the body's own production. The hypothalamic-pituitary-gonadal axis senses circulating testosterone, suppresses gonadotropin-releasing hormone (GnRH) at the hypothalamus and luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at the pituitary, and Leydig cell steroidogenesis and Sertoli-cell-dependent spermatogenesis fall toward zero. For men whose symptoms are severe and whose fertility is no longer a consideration, that trade-off is acceptable. For men who want to preserve fertility, for men uncertain whether they want lifelong exogenous hormone therapy, or for men whose hypogonadism is secondary (a hypothalamic-pituitary problem rather than a testicular one), HPG-axis-stimulating peptides become a different and mechanistically distinct conversation. This dossier surveys what the published literature actually supports for that alternative pathway — and where the marketing of these tools outruns the evidence.