Why ‘Age-Appropriate’ Hormone Levels Are a Flawed Concept

“Your levels are normal for your age.”

This is one of the most common phrases a patient hears when questioning their hormone results. It is intended to be reassuring. For many patients, it is the opposite. They feel terrible. Their blood work is “normal.” The implication is that feeling terrible is, at their age, normal.

The concept of age-appropriate hormone levels contains a logical error that, once identified, changes how both patients and physicians approach hormonal health.

How Age-Specific Reference Ranges Are Built

Laboratory reference ranges are derived from population data. A reference range for total testosterone in men represents the central 95 percent of values in a sample of adult men. When that sample is stratified by age, the resulting ranges naturally decline with each decade.

This is expected. Testosterone does decline with age in the general population. The reference range reflects this decline. A testosterone level of 12 nmol/L in a 60-year-old man falls within the age-specific reference range because most 60-year-old men have similar levels.

The problem is that most 60-year-old men in the population that generates reference ranges are also overweight, insulin resistant, sedentary, sleep-deprived, and chronically stressed. The reference range does not distinguish between the natural, minimal decline that occurs in healthy aging and the accelerated decline driven by modifiable metabolic and lifestyle factors. Aging itself does cause some hormone decline—this is physiological. But the degree of decline in the general population exceeds what is seen in healthy, metabolically optimized individuals.

Research on populations that maintain metabolic health, exercise regularly, and manage stress shows substantially smaller age-related hormone decline. The reference range conflates the disease-driven decline with the age-driven decline. It tells you what is statistically common in a largely unwell population. It does not tell you what is healthy.

Normal Is Not Optimal

A man at 50 with a total testosterone of 13 nmol/L is told his level is “within the normal range for his age group.” This may be statistically accurate. But that same man at 30 likely had a level of 22 to 25 nmol/L. He has lost 40 to 50 percent of his testosterone, and his symptoms (fatigue, poor recovery, abdominal weight gain, reduced libido, irritability) correspond precisely to the magnitude of the decline.

Telling him his levels are appropriate for his age is equivalent to telling a person with gradually worsening vision that their eyesight is “normal for their age.” It may be true that many people their age see poorly. That does not mean poor vision should go uncorrected.

The question is not whether the decline is common. The question is whether the patient is symptomatic, whether the decline is measurable, and whether restoration would improve their health and quality of life.

The Population in the Reference Range

The population from which age-specific reference ranges are derived is not a population of healthy, optimized individuals. It includes everyone who had blood drawn: patients with undiagnosed metabolic syndrome, men with obstructive sleep apnea, women on oral contraceptives, individuals on multiple medications, people who are sedentary, and people who are chronically ill.

These comorbidities lower the population average. The reference range captures this lowered average and presents it as the norm. A physician who treats to the reference range is, in effect, treating to the average level of a largely unwell population. The ranges are not derived from people who exercise regularly, who sleep eight hours per night, who manage their stress, who eat whole food diets, and who maintain metabolic health. They are derived from everyone.

Consider an analogy: if you measured hemoglobin levels in a population where 40% are anemic and 30% have undiagnosed malignancy, the “normal” range would be lower than it would be in a healthy population. The reference range would mislead you about what is healthy.

Functional medicine practitioners use a different framework. They compare a patient’s levels to optimal physiological ranges, the ranges associated with symptom resolution, metabolic health, and functional capacity, rather than to the population average. These ranges are narrower than standard laboratory ranges because they are anchored to clinical outcomes, not statistical distributions.

The Estrogen Parallel in Women

The same logic applies to estrogen in women. A postmenopausal woman with an estradiol of 20 pmol/L is told this is “normal for menopause.” And it is. Estrogen is supposed to decline after menopause. But the consequences of that decline, vasomotor symptoms, bone loss, vaginal atrophy, cardiovascular risk acceleration, cognitive changes, and joint pain, are not inevitable consequences to be endured. They are treatable.

Accepting menopausal estrogen levels as appropriate because they are common conflates prevalence with acceptability. The same woman at 35 had an estradiol of 400 to 600 pmol/L and none of these symptoms. The decline is real and the consequences are measurable. Whether to treat is a clinical decision, not a statistical one.

The Thyroid Example

Age-specific TSH ranges illustrate the same problem. TSH tends to rise with age in population studies, leading some reference laboratories to adjust the upper limit of normal upward for older adults.

A TSH of 5.0 in a 70-year-old may fall within an age-adjusted reference range. But a TSH of 5.0 is associated with elevated LDL cholesterol, reduced cognitive function, and impaired metabolic rate in multiple studies. The age-adjusted range has not made the patient healthier. It has redefined their dysfunction as normal.

What Functional Ranges Look Like

Functional reference ranges are narrower than standard laboratory ranges and are anchored to clinical outcomes rather than statistical distributions.

For total testosterone in men, a functional optimal range might be 18 to 28 nmol/L, regardless of age. For free testosterone, the upper half of the standard range is the target. For TSH, most functional medicine practitioners consider 0.5 to 2.0 mIU/L optimal. For fasting insulin, below 5 to 6 µIU/mL.

These ranges are derived from clinical experience, population health data (not population disease data), and the published literature on symptom thresholds and health outcomes.

They represent the ranges at which patients feel well, function well, and maintain the metabolic and hormonal milieu associated with long-term health. They are targets, not merely reference points.

The Clinical Conversation

When a patient is told their levels are “normal for their age,” the productive response is to ask: normal compared to whom? Normal compared to chronically ill, metabolically dysfunctional people who also happen to be your age?

Better questions are: What was my likely level at 30? Has my level declined faster than expected, or in line with what is seen in the general population of the same age who includes everyone? Is there evidence that restoring me to a higher level within the physiological range would improve my symptoms? What are the risks of treatment versus the risks of leaving these levels where they are?

These are questions that a physician experienced in hormonal optimization can answer with data and literature. The conversation shifts from “you’re fine” to “here is where you are, here is where optimal is based on evidence about symptom thresholds and health outcomes, here is what you likely were at 30, and here is what the evidence says about the safety and efficacy of closing that gap.”

The conversation also requires honesty about what “normal” means. It is easier to say “you’re normal for your age” than to say “your levels reflect metabolic dysfunction.” But only the latter conversation leads to intervention.

The Goal Is Function, Not Conformity

Hormone optimization does not aim to make a 55-year-old’s blood work look like a 25-year-old’s. It aims to restore hormonal levels to a range where symptoms resolve, metabolic health is maintained, physical capacity is supported, and quality of life is preserved.

That range may differ from patient to patient. It is determined by the individual’s clinical response, not by a statistical average of a population that includes many people who are unwell.

“Normal for your age” is a description of where the average person lands. It is not a prescription for where you should remain.

Continue Reading

If you found this useful, these related articles may deepen your understanding:

• Your TSH Is Normal but You’re Still Exhausted
• Your Testosterone Is ‘Normal’ but You Still Feel Terrible
• What the WHI Got Wrong

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Dr. Handsun Xiao is a McGill trained physician (MD, CCFP) practicing functional medicine and bioidentical hormone therapy in Toronto, with virtual consultations available to patients across Ontario. He holds advanced BHRT certification through WorldLink Medical and IFM AFMCP training. Manus Solis offers physician led BHRT consultations with custom compounding through a dedicated Ontario pharmacy partner. To learn more or book a virtual consultation, visit manussolis.ca.