There is no published age-stratified adult reference range for male total testosterone. Instead, major diagnostic facilities report a single uniform interval covering adult men from age 18 to age 90. The two largest commercial testing companies in the United States do not agree on that baseline range. Furthermore, the 264 to 916 ng/dL adult band was measured only in non-obese men aged 19 to 39.
The Verdict
Testosterone Levels by Age in Clinical Reference Ranges
Commercial diagnostic laboratories do not divide adult male testosterone ranges into separate age brackets. While laboratories provide detailed age intervals for pediatric populations and pubertal progression, that stratification ends at age 18. An 80-year-old man and a 20-year-old man receive identical normal reference intervals on standard commercial lab reports.
Reference figures published by Labcorp show that stratification ceases once puberty concludes. The Tanner stage intervals overlap across chronological ages because pubertal development occurs at varying rates. Two boys of the same chronological age can sit in different developmental stages with substantially different expected hormone levels. Adult reference intervals collapse these distinctions.
The standard adult reference band of 264 to 916 ng/dL was established by Travison and colleagues in a 2017 study. The Endocrine Society described this work as a landmark study defining normal ranges for total testosterone. The researchers established this harmonized interval by pooling data from 9,054 men across four epidemiologic cohort studies in the United States and Europe. The resulting normal range represents the 2.5th to 97.5th percentiles of the study population.
This harmonized cohort was restricted to men aged 19 to 39 with a body mass index (BMI) under 30. All testing used liquid chromatography-tandem mass spectrometry (LC-MS/MS) calibrated against the higher-order reference method of the Centers for Disease Control and Prevention (CDC). Within this young, non-obese population, the median total testosterone was 531 ng/dL. The interquartile range (IQR) spanned 424 to 643 ng/dL. Older men were entirely excluded. Consequently, the resulting 264 to 916 ng/dL interval does not represent an age-adjusted normal range for middle-aged or older men.
| Stage or Age Group | Age Range | Reference Interval |
|---|---|---|
| Premature infant (day 4) | 26 to 28 weeks gestation | 59.0 to 125.0 ng/dL |
| Premature infant (day 4) | 31 to 35 weeks gestation | 37.0 to 198.0 ng/dL |
| Newborn | Full term | 75.0 to 400.0 ng/dL |
| Male child | 1 to 10 years | Under 2.5 to 10.0 ng/dL |
| Tanner Stage I | Under 9.8 years | Under 2.5 to 10.0 ng/dL |
| Tanner Stage II | 9.8 to 14.5 years | 18.0 to 150.0 ng/dL |
| Tanner Stage III | 10.7 to 15.4 years | 100.0 to 320.0 ng/dL |
| Tanner Stage IV | 11.8 to 16.2 years | 200.0 to 620.0 ng/dL |
| Tanner Stage V | 12.8 to 17.3 years | 350.0 to 970.0 ng/dL |
| Adult male | Over 18 years | 264.0 to 916.0 ng/dL |
Why Labcorp and Quest Diagnostics Report Different Ranges
The two largest commercial laboratories in the United States report different adult normal ranges for total testosterone despite both using CDC-standardized testing methods. Labcorp reports an adult male reference interval of 264.0 to 916.0 ng/dL for men over 18 years of age. This interval directly adopts the harmonized figures from Travison and colleagues. In contrast, Quest Diagnostics reports an adult male interval of 250 to 1100 ng/dL for men aged 18 and older under test code 15983, which measures total testosterone using LC-MS/MS.
The difference stems from population selection. Quest Diagnostics derived its lower limit of 250 ng/dL from the 2.5th percentile of results in a healthy population of men extending up to age 90. By including older adult men in its sample, Quest Diagnostics established a wider distribution than Labcorp. The Quest Diagnostics assay is certified by the CDC Hormone Standardization (HoSt) program. It has a reportable range of 1.0 to 10,000 ng/dL. The assay shows zero cross-reactivity with 30 testosterone-related compounds.
This difference produces conflicting clinical flags. Consider an adult male patient whose circulating total testosterone measures 260 ng/dL. Tested through Quest Diagnostics, this level falls within the reported 250 to 1100 ng/dL normal range and generates an unremarkable lab result. Tested through Labcorp, that same 260 ng/dL reading falls below the 264.0 ng/dL cutoff and is flagged as an abnormal low value. Both assays are CDC-traceable. Yet the reported reference status directly conflicts.
Reference Range Versus Diagnostic Threshold
Clinical diagnosis of testosterone deficiency relies on fixed clinical cutoffs and documented symptoms rather than laboratory reference intervals alone. The American Urological Association (AUA) guideline recommends that clinicians use a total testosterone level below 300 ng/dL as a reasonable cutoff supporting a diagnosis of low testosterone. The AUA classifies this instruction as a Moderate Recommendation with Evidence Level Grade B. In parallel, the Endocrine Society guidelines recommend using the harmonized lower reference limit of 264 ng/dL on CDC-certified assays.
Both associations require clinical symptoms. A low number alone does not establish a diagnosis. The AUA clinical guidelines set rigorous standards for confirming low testosterone before initiating medical care:
- A diagnosis requires two separate total testosterone measurements drawn on different occasions.
- The AUA specifies that both blood collections take place in the early morning.
- The clinical evaluation requires documented physical signs and symptoms of deficiency in addition to low circulating levels.
Total, Free, and Bioavailable Testosterone
Routine laboratory testing for testosterone measures the total circulating concentration of the hormone in the bloodstream. Total testosterone accounts for all hormone present in circulation, including molecules bound to sex hormone-binding globulin and albumin. In clinical evaluations, physicians frequently assess free testosterone and bioavailable testosterone alongside total levels to build a fuller hormonal profile.
Free testosterone represents the unbound fraction. Bioavailable testosterone encompasses both the free fraction and the portion bound loosely to albumin. Neither the harmonized international consensus nor major diagnostic guidelines provide a universal free testosterone reference range or bioavailable testosterone reference range.
Measurement techniques differ between facilities. Because analytical platforms vary, each commercial laboratory establishes its own internal reference intervals for these fractions. Any reported free or bioavailable value must be evaluated strictly against the specific reference interval printed on that laboratory report. For a fuller review of diagnostic tests, see the guide to a men's hormone panel.
Why the Harmonized Range Excluded Men with Obesity
The landmark harmonized reference range intentionally excluded men with obesity to prevent metabolic pathology from lowering the definition of normal testosterone. In the 2017 study by Travison and colleagues, researchers observed that obesity is directly associated with lower circulating testosterone levels. Including men with a body mass index (BMI) of 30 or higher would have depressed the statistical distribution of the cohort.
This downward shift would have forced the 2.5th percentile lower limit below 264 ng/dL. Metabolic impairment would then look statistically normal.
Because the harmonized 264 to 916 ng/dL interval represents healthy non-obese young men, it describes a narrower group than the adult men it is applied to. The relationship between metabolic impairment and endocrine markers is detailed further in the overview of metabolic syndrome criteria.
Measurement Units and the nmol/L Reporting System
Commercial laboratories in the United States report testosterone concentrations in nanograms per deciliter, whereas international laboratories commonly report in nanomoles per liter. Readers comparing a result against international literature encounter both scales. In the United States, commercial reference facilities such as Labcorp and Quest Diagnostics standardize their reporting on the ng/dL scale. International health systems across Europe and other regions typically express total testosterone in nmol/L.
Both reporting systems remain valid. Because different testing platforms use distinct calibration standards, numerical results must be read exclusively against the specific reference interval and measurement units provided on the official laboratory report. A figure in one unit system cannot be read against a range stated in the other. Testosterone results are read against the reference interval of the lab that produced them, and that reading is a conversation for a clinician.
Frequently Asked Questions
What is a normal testosterone level by age?
There is no standardized adult reference range for normal testosterone levels by age. Major commercial laboratories report a single adult male interval spanning ages 18 to 90. Labcorp uses an adult interval of 264.0 to 916.0 ng/dL, while Quest Diagnostics reports a range of 250 to 1100 ng/dL. The landmark harmonized range of 264 to 916 ng/dL was established from a reference population of non-obese men aged 19 to 39.
Is there a testosterone levels by age chart?
No official adult testosterone levels by age chart exists in clinical guidelines or commercial laboratory reporting. While laboratories publish age-stratified intervals for pediatric and pubertal populations through Tanner stages up to age 18, all adult men are grouped into a single reference bracket. Clinical reference standards evaluate all adult men against a uniform statistical range rather than decade-by-decade categories.
What is a normal testosterone level for a 36 year old male?
A normal testosterone level for a 36-year-old male falls within the standard adult reference interval of 264 to 916 ng/dL. Travison and colleagues established that interval in men aged 19 to 39 with a BMI under 30. In that reference cohort, the median total testosterone concentration was 531 ng/dL, with the middle 50 percent of participants falling between 424 and 643 ng/dL. Commercial laboratories evaluate this result against their adult male reference range, such as 264 to 916 ng/dL at Labcorp or 250 to 1100 ng/dL at Quest Diagnostics.
What testosterone level is considered low?
The American Urological Association guidelines state that a total testosterone level below 300 ng/dL supports a diagnosis of testosterone deficiency when accompanied by clinical signs and symptoms. The Endocrine Society defines low testosterone using the harmonized lower limit of 264 ng/dL on CDC-certified assays. Both organizations require low levels to be confirmed with two separate morning blood draws.
Why do Labcorp and Quest report different testosterone ranges?
Labcorp and Quest Diagnostics report different adult reference intervals because they derived their statistical boundaries from different reference populations. Labcorp uses 264.0 to 916.0 ng/dL, which reflects the harmonized 2017 study of non-obese men aged 19 to 39. Quest Diagnostics reports 250 to 1100 ng/dL, which was derived from the 2.5th percentile of healthy men up to age 90. Both assays use LC-MS/MS and are certified by the CDC, but their selected healthy cohorts differ in age composition.
What are normal testosterone levels for women?
The harmonized 264 to 916 ng/dL range and the 300 ng/dL AUA threshold are both male figures, and neither applies to women. Labcorp and Quest report female testosterone against separate intervals on their own test pages. To review expected hormonal patterns and laboratory testing protocols for women, consult the guide on the perimenopause biomarker panel.
Do testosterone levels need to be measured in the morning?
Yes, clinical guidelines strongly recommend collecting blood samples in the early morning. The American Urological Association designates the requirement for two early-morning blood draws as a Strong Recommendation with Evidence Level Grade A. The same guideline treats a single low result as insufficient on its own: the diagnosis also requires documented signs and symptoms.
What is the difference between total and free testosterone?
Total testosterone measures all circulating testosterone in the blood, including hormone bound to proteins such as sex hormone-binding globulin and albumin. Free testosterone measures only the unbound, biologically active fraction circulating in plasma. Laboratories establish internal reference ranges for free testosterone that must be interpreted against the specific testing facility's reported interval.