Testosterone levels by age: how to read your result

How testosterone changes with age

Unlike menopause, which brings a fairly rapid fall in estrogen, testosterone in men declines gradually. MedlinePlus describes it as a general slowing rather than an abrupt loss, and some men keep levels well within the normal range into old age. The steep drops seen in some men are often linked to weight gain and chronic illness rather than age alone.

A 2017 review in the Journal of Clinical Endocrinology & Metabolism reported that gaining a few points of BMI or developing type 2 diabetes was associated with a fall in testosterone equivalent to about a decade of aging. In other words, health status often matters more than birthday.

Why a by-age chart can mislead

Reference ranges differ between labs because they use different testing methods and draw on different populations. Some labs report age-adjusted ranges, which can make a low level in an older man look normal; others use a single adult range. Two labs can label the same number differently.

The Endocrine Society addressed this by defining a harmonized lower limit of 264 ng/dL for healthy, non-obese young men, applicable to assays certified by the CDC's standardization program. The AUA uses 300 ng/dL as a reasonable cutoff. Neither is a target to chase; both are thresholds below which deficiency becomes likely if symptoms are present.

Timing and conditions matter

Testosterone peaks in the morning and falls through the day. MedlinePlus advises drawing blood around 7 to 10 a.m. The Endocrine Society notes that aging blunts the morning peak, so some older men with low afternoon levels turn out to be normal in the morning.

Acute illness, a very poor night's sleep, heavy exercise the day before, fasting or overeating can all shift a single result. That is why guidelines require two morning measurements on separate days before diagnosing deficiency, and why the test is best done when you are well.

Total, free and SHBG

Most testosterone in your blood is bound to proteins, mainly sex hormone-binding globulin (SHBG) and albumin. Total testosterone measures all of it. Free testosterone is the small unbound fraction that tissues can use directly.

SHBG tends to rise with age and with some conditions, which can leave total testosterone looking acceptable while free testosterone is low. Obesity and insulin resistance tend to lower SHBG, which can make total testosterone look low even when free testosterone is adequate. The Endocrine Society recommends measuring free testosterone by equilibrium dialysis or a validated calculation when SHBG is abnormal or total testosterone is borderline, and says direct analog free testosterone tests are inaccurate.

What a low result should lead to

These steps follow the AUA and Endocrine Society guidelines and help avoid treating a temporary dip or missing a cause that needs its own care.

• A repeat morning test on a different day
• LH and FSH, to tell whether the problem is in the testes or in the brain's signals
• Prolactin if LH is low or normal
• SHBG and free testosterone when results are borderline
• A look at reversible causes: weight, sleep apnea, alcohol, opioids and other medications, and chronic illness
• Hematocrit and, for men over 40, PSA if treatment is being considered

Preparing for an accurate test

Small steps like these make your result more reliable and reduce the chance of being treated, or turned away, on the basis of a misleading number.

• Book an early-morning appointment, ideally before 10 a.m.
• Avoid testing during or right after an illness
• Get a normal night's sleep beforehand
• Skip unusually hard exercise the day before
• Ask whether to fast; some labs and clinicians prefer a fasting sample
• If you already take testosterone, ask when to draw blood relative to your dose

Symptoms carry as much weight as the number

In the European Male Ageing Study, sexual symptoms such as fewer morning erections, low libido and erectile dysfunction were most strongly linked to low testosterone. Fatigue and low mood were only weakly linked, because they have so many other causes.

Guidelines are clear that a low level without symptoms is not a reason to treat, and the Endocrine Society does not recommend routinely treating all men over 65 with low testosterone. Treatment is a decision based on both the numbers and how you are actually doing.

Can you raise it without medication?

Sometimes. Losing excess weight, treating sleep apnea, cutting back on alcohol, reviewing medications such as opioids and getting regular exercise can all help, particularly when low testosterone is functional rather than due to testicular or pituitary disease.

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