Men's Health After 40: The Hormonal Shift Nobody Prepares You For

Testosterone: The Central Variable

Total testosterone peaks in the early-to-mid 20s and declines at approximately 1–2% per year beginning around age 30, with some studies suggesting the decline accelerates after 40. By age 50, average testosterone levels are 20–30% below peak. By age 70, average levels are 40–50% below peak.

The clinical consequences of declining testosterone are multiple and interacting:

• —Muscle mass and strength — testosterone is the primary anabolic driver for skeletal muscle; declining testosterone accelerates sarcopenia
• —Adiposity — low testosterone is associated with preferential accumulation of visceral adiposity and metabolic syndrome
• —Bone density — hypogonadism is a major driver of osteoporosis in men, a condition substantially underappreciated in this population
• —Cognitive function — testosterone has direct effects on hippocampal neurogenesis, working memory, and executive function
• —Mood and energy — testosterone deficiency is a recognized contributor to depression, fatigue, and reduced motivation
• —Cardiovascular risk — the relationship between testosterone and cardiovascular disease is complex and context-dependent

Free vs. Total Testosterone

Most standard laboratory panels report total testosterone. Clinically, free testosterone — the biologically active fraction not bound to sex hormone-binding globulin (SHBG) or albumin — is often more informative, particularly in men with elevated SHBG, which increases with age. A man with a total testosterone of 450 ng/dL and an SHBG of 80 nmol/L may have a free testosterone level equivalent to a man with total testosterone of 250 ng/dL — and may be far more symptomatic. Evaluation of both total and calculated free testosterone is standard at Analog Precision Medicine.

DHEA: The Overlooked Adrenal Androgen

Dehydroepiandrosterone (DHEA) and its sulfate form (DHEA-S) are produced predominantly by the adrenal cortex and serve as precursors to both testosterone and estrogen. DHEA declines at approximately 2–3% per year beginning in the late 20s — an even steeper trajectory than testosterone. By age 70, DHEA-S levels are typically 80–90% below peak values.

DHEA has established roles in immune function, insulin sensitivity, neuroprotection, and mood regulation. Low DHEA-S is independently associated with all-cause mortality in several cohort studies. Supplementation (25–50 mg/day) has positive signals in bone density, mood, and sexual function, though results for cardiovascular markers and longevity endpoints are inconsistent.

Cortisol: Chronic Stress and the HPA Axis

In high-performing men over 40 — executives, entrepreneurs, physicians, competitive athletes — chronic stress produces sustained HPA activation with several downstream consequences:

• —Testosterone suppression — elevated cortisol directly inhibits hypothalamic GnRH release and testicular testosterone synthesis
• —Insulin resistance — cortisol promotes hepatic gluconeogenesis and peripheral insulin resistance, driving visceral adiposity
• —Cognitive effects — elevated glucocorticoid exposure accelerates hippocampal volume loss and cognitive aging
• —Sleep disruption — elevated evening cortisol suppresses melatonin and blunts the nocturnal parasympathetic shift

Evaluating cortisol dynamics — not just fasting morning cortisol but salivary diurnal cortisol curves and urinary cortisol metabolites — provides a more complete picture of HPA axis function than standard serum morning cortisol alone.

Thyroid Function in Aging Men

Thyroid dysfunction increases with age but is systematically under-screened in men. Subclinical hypothyroidism — elevated TSH with normal free T4 — is present in approximately 4–8% of middle-aged men and has dose-dependent associations with dyslipidemia, cardiovascular risk, and cognitive symptoms. TSH alone is an inadequate screen. Free T3, free T4, reverse T3, and thyroid antibodies provide a complete picture that TSH-only screening misses.

Growth Hormone and the Somatotropic Axis

Growth hormone secretion at age 60 is approximately 25% of levels in young adulthood. IGF-1 declines in parallel. The clinical consequences include reduced muscle protein synthesis, impaired lipid metabolism, decreased bone density, and reduced exercise capacity. Low IGF-1 in older men is associated with increased all-cause mortality in several cohort studies.

GHRP/secretagogue peptides (sermorelin, ipamorelin, tesamorelin) stimulate endogenous GH release with a more physiological secretory pattern and reduced side effect profile compared to exogenous GH, though they exist in a regulatory gray area not approved for longevity indications.

TRT and the TRAVERSE Trial

The TRAVERSE trial (published in NEJM in 2023) was the largest prospective randomized trial of TRT in men at cardiovascular risk, enrolling over 5,200 men. Key findings: TRT was non-inferior to placebo for major adverse cardiovascular events, but increased risk of atrial fibrillation, acute kidney injury, and pulmonary embolism in the treatment group.

In appropriately selected men with confirmed hypogonadism, TRT does not appear to increase heart attack or stroke risk — but does carry elevated risk for AFib and venous thromboembolism. This reshapes but does not eliminate the cardiovascular risk discussion.

Estradiol: The Male Hormone Most Men Don't Know They Have

Estradiol is produced in men through aromatization of testosterone in peripheral tissues. It is not a "female hormone" to be minimized. Estradiol maintains bone mineral density in men — the majority of the anabolic effect on male bone is estrogen-mediated — and modulates libido, mood, and cognitive function. Low estradiol produces joint pain, osteopenia, and mood disturbance; supraphysiologic levels from excessive aromatization produce gynecomastia and sexual dysfunction. Evaluation of estradiol is standard at Analog Precision Medicine yet frequently omitted in primary care testosterone panels.

The Comprehensive Male Hormonal Assessment

A complete male hormonal evaluation at Analog Precision Medicine includes:

• —Total and free testosterone (morning draw, at least two measurements before treatment decisions)
• —LH and FSH (differentiates primary from secondary hypogonadism)
• —SHBG (required to calculate free testosterone accurately)
• —Estradiol (sensitive LC-MS/MS assay — standard immunoassay methods are inaccurate at male physiological levels)
• —DHEA-S
• —IGF-1 and GH axis assessment as clinically indicated
• —TSH, free T3, free T4, reverse T3, TPO antibodies
• —PSA (baseline before any testosterone initiation)
• —Complete metabolic panel, lipid panel, CBC
• —Salivary or urinary cortisol when clinical picture suggests HPA dysregulation

Bottom Line

The hormonal shift that begins for most men in their 40s is not a single variable and it is not inevitable in its consequences. It is a coordinated downregulation across multiple interacting systems — testosterone, DHEA, growth hormone axis, thyroid, cortisol dynamics — that can be assessed comprehensively, contextualized individually, and addressed with interventions ranging from lifestyle optimization to hormonal therapy where indicated.

The men who fare best in their 50s, 60s, and beyond are not the ones who ignore the shift. They are the ones who identify it early, understand what is driving it, and address it with the same systematic rigor they would apply to any other high-stakes optimization challenge.

References

1. 1. Harman SM, et al. Longitudinal effects of aging on serum total and free testosterone levels. J Clin Endocrinol Metab. 2001;86(2):724–731.
2. 2. Grossmann M. Low testosterone in men with type 2 diabetes. J Clin Endocrinol Metab. 2011;96(8):2341–2353.
3. 3. Moffat SD, et al. Free testosterone and risk for Alzheimer disease in older men. Neurology. 2004;62(2):188–193.
4. 4. Orentreich N, et al. Age changes and sex differences in serum DHEA sulfate concentrations. J Clin Endocrinol Metab. 1984;59(3):551–555.
5. 5. Lupien SJ, et al. Cortisol levels during human aging predict hippocampal atrophy. Nat Neurosci. 1998;1(1):69–73.
6. 6. Rodondi N, et al. Subclinical hypothyroidism and the risk of coronary heart disease. JAMA. 2010;304(12):1365–1374.
7. 7. Corpas E, et al. Human growth hormone and human aging. Endocr Rev. 1993;14(1):20–39.
8. 8. Lincoff AM, et al. Cardiovascular safety of testosterone-replacement therapy. N Engl J Med. 2023;389(2):107–117.