The Male Andropause —
What Low T Actually Means

The andropause is not a myth and it is not the male equivalent of menopause — the two are biologically different in ways that matter clinically. Menopause is an event: ovarian function ceases within a relatively defined window, oestrogen and progesterone fall sharply, FSH rises dramatically. Andropause is a gradient: testicular Leydig cell function declines gradually over decades, testosterone falls at roughly 1–2% per year from the mid-thirties, and there is no equivalent of the FSH surge that marks female gonadal failure.

This distinction has important clinical consequences. A man of 55 with symptoms of low testosterone — fatigue, reduced libido, poor recovery, mood flattening, muscle loss, abdominal fat accumulation, poor morning erections — may have testosterone in the lower third of the laboratory reference range. But that reference range was derived from a population that includes men in their seventies with genuinely depleted production. "Normal" on a serum testosterone result frequently means "not deficient by population standards that include the elderly." That is not the same as optimal.

More importantly, the serum total testosterone result tells you less than half the clinical story. The half it does not tell you — the free fraction, the SHBG binding, the downstream conversion to DHT and oestradiol, the HPA-HPG axis interaction — is where the actual clinical picture lives.

The testosterone system — what total T doesn't show you

Testosterone in the bloodstream exists in three fractions. Approximately 44% is bound tightly to sex hormone binding globulin (SHBG) — this fraction is biologically inactive and unavailable to cells. Approximately 54% is loosely bound to albumin — this is weakly bound and can dissociate at tissue level, making it potentially bioavailable. Approximately 2–3% is free — unbound, immediately bioavailable to enter cells and bind androgen receptors.

A standard serum testosterone test measures total testosterone — the sum of all three fractions. A man with high SHBG will have adequate total testosterone and genuinely low free testosterone. His serum result looks normal. His androgen receptor activation is inadequate. His symptoms are real and have a biochemical explanation that the standard test cannot see.

SHBG — the variable that changes everything

Sex hormone binding globulin is produced by the liver and rises with age, with oestrogen exposure, with hyperthyroidism, and with significant weight loss. It falls with obesity, with insulin resistance, with hypothyroidism, and with elevated androgens. Because SHBG binds testosterone tightly, high SHBG reduces the free fraction available to tissues even when total testosterone is adequate.

The clinical consequences are significant and frequently missed. A man of 50 with total testosterone of 16 nmol/L (mid-normal range), SHBG of 65 nmol/L (elevated), and calculated free testosterone of 0.22 nmol/L (below the optimal threshold) has genuine androgen insufficiency at tissue level despite a "normal" blood test. His GP will likely reassure him that his testosterone is fine. Functionally, it is not.

The reverse is equally important. A man with insulin resistance and elevated body fat often has low SHBG, which means his free testosterone fraction is proportionally higher relative to total testosterone. His total testosterone may look low-normal but his free testosterone is adequate. In this case the clinical intervention is not testosterone replacement — it is addressing the insulin resistance and visceral adiposity that are driving the system dysregulation.

Primary versus secondary hypogonadism — the distinction that determines treatment

This is the most clinically important differential in the male hormone picture and the one most frequently bypassed in both NHS and private testosterone prescribing. The failure mode — prescribing testosterone without establishing whether the axis problem is primary (testicular) or secondary (hypothalamic-pituitary) — has meaningful consequences for both efficacy and safety.

The practical implication: before any testosterone replacement is initiated, LH and FSH must be measured alongside testosterone. This is not done routinely in many NHS or private testosterone clinics. It is essential clinical information.

Oestradiol in men — the marker most TRT conversations ignore

Men produce oestradiol. They need it — for bone density, cardiovascular health, cognitive function, libido, and joint integrity. Men with undetectable oestradiol following aggressive TRT or aromatase inhibitor use develop osteoporosis, joint pain, and loss of libido despite adequate testosterone levels. The target is not zero oestradiol. The target is an appropriate testosterone-to-oestradiol ratio.

Aromatase — the enzyme that converts testosterone to oestradiol — is found throughout the body but is most active in adipose tissue. This creates the clinical pattern seen in overweight men with low testosterone: high aromatase activity in visceral fat converts available testosterone to oestradiol, oestradiol feeds back to suppress LH (and therefore further testosterone production), and a progressive cycle of declining testosterone and rising oestradiol establishes itself. This is secondary hypogonadism driven by body composition — and it resolves with weight management far more reliably than with testosterone replacement.

The DUTCH male hormone assessment includes total testosterone, free testosterone (calculated), oestradiol, and the testosterone and oestrogen metabolite picture that blood testing cannot provide. Specifically it shows the 2-OH and 16-OH oestrogen metabolite pathways in men — directly relevant to prostate cancer risk assessment and to understanding whether the oestrogen load is being processed safely. A man on TRT who has never had his oestrogen metabolite picture assessed is being managed with incomplete information.

The complete testing picture for male hormone assessment

Testosterone replacement options — the clinical comparison

Fertility — the critical conversation before TRT

Exogenous testosterone suppresses the HPG axis. When testosterone is introduced from outside, the hypothalamus reduces GnRH pulsing, LH falls, and intratesticular testosterone — required for sperm production — plummets. Spermatogenesis requires local testosterone concentrations approximately 100 times higher than serum levels. Standard TRT effectively suppresses sperm production in most men within weeks to months.

Recovery of fertility after TRT cessation is possible but not guaranteed and can take 6–24 months. For any man under 45 who has not completed his family, this conversation must happen before TRT is initiated. The clinical alternative — hCG (human chorionic gonadotropin), which mimics LH and maintains intratesticular testosterone — can be used alongside TRT to preserve spermatogenesis, or alone as a fertility-preserving option for secondary hypogonadism.

The functional medicine approach — what to address before TRT

For the man with secondary hypogonadism driven by lifestyle and metabolic factors — which represents a large proportion of men presenting with low testosterone symptoms in their forties and early fifties — the upstream drivers frequently respond to intervention without TRT ever being necessary:

• Visceral fat reduction — directly reduces aromatase activity and improves the testosterone-to-oestradiol ratio. Meaningful improvement in free testosterone is consistently documented with 10–15% body weight reduction in overweight hypogonadal men.
• HPA axis support — cortisol suppression of GnRH is reversible. The RSS programme framework applied to secondary hypogonadism can restore the HPG axis signal without exogenous testosterone.
• Sleep quality — 80% of daily testosterone production occurs during sleep, particularly deep sleep and early morning hours. Sleep apnoea is a major cause of secondary hypogonadism and is treatable.
• Zinc and vitamin D — both are required for testosterone synthesis. Zinc deficiency directly impairs Leydig cell function. Vitamin D receptors are present in Leydig cells. Both are consistently found deficient in hypogonadal men and both have evidence for improving testosterone when corrected.
• Insulin resistance management — hyperinsulinaemia reduces SHBG (increasing total/free ratio but also increasing aromatase) and drives the visceral fat accumulation that is itself the primary driver. Blood chemistry with fasting insulin and HbA1c belongs in every male hormone assessment.