Free Testosterone Test: Range, Methods & Results

Quick answer

What does a free testosterone result mean?

Free testosterone is the small fraction of testosterone not bound to sex hormone-binding globulin (SHBG) or albumin at the time of testing. It can add useful context when total testosterone is near a decision boundary or SHBG is unusual. The first question is how it was obtained: equilibrium dialysis and a validated calculation from accurate total testosterone, SHBG and albumin are not interchangeable with a common direct analogue immunoassay. There is no universal free-testosterone optimal range, so interpret the original method-specific laboratory interval with symptoms, sex, age, life stage, timing and related hormones—not the number alone.^{See reference 1,See reference 2,See reference 3,See reference 6,See reference 8}

Quick answer

What does a free testosterone result mean?

Six points that prevent most free-testosterone mistakes

Method comes first. Equilibrium dialysis is the reference-style direct approach; a validated calculation can be useful; a direct analogue immunoassay is not equivalent and may be inaccurate.^{See reference 1,See reference 3,See reference 6,See reference 8,See reference 12}
No single worldwide normal or optimal range applies across methods, laboratories, sexes, ages, pregnancy or hormone therapy. Use the interval printed for that exact assay.^{See reference 1,See reference 7,See reference 8}
Free testosterone is not the same as total testosterone, percent free testosterone, bioavailable testosterone or the free-androgen index.^{See reference 1,See reference 4,See reference 10,See reference 14}
In men assessed for possible hypogonadism, symptoms plus repeat accurate morning testing matter; one low result does not prove a diagnosis or need for treatment.^{See reference 1,See reference 2,See reference 3}
SHBG can make total and free testosterone move differently. Albumin, medicines, illness, collection timing and the calculation equation can also change interpretation.^{See reference 1,See reference 3,See reference 11}
Testosterone treatment can suppress fertility, harm a fetus and transfer from gel to children or partners. Never change treatment from a converter or one result.^{See reference 15,See reference 16,See reference 17,See reference 18}

Free, total, bioavailable and calculated testosterone are different

Most circulating testosterone is bound to SHBG or albumin. Free testosterone is the unbound fraction. Total testosterone includes free and protein-bound hormone. Bioavailable testosterone usually combines free and weakly albumin-bound testosterone, so it is a different analyte.^{See reference 10,See reference 14}

Calculated free testosterone is an estimate made from total testosterone, SHBG and albumin using a named binding equation. Percent free testosterone is a percentage, while free-androgen index is usually 100 × total testosterone divided by SHBG. Neither should be relabelled as a measured free-testosterone concentration.^{See reference 3,See reference 4,See reference 11}

DHT and DHEA-S are also different hormones. A result is most informative when its exact analyte, method, unit and related markers stay attached to it.^{See reference 4,See reference 14}

How free testosterone is measured or estimated

Report method: Equilibrium dialysis, followed by a suitable testosterone measurement
What it does: Separates unbound testosterone across a membrane and measures the dialysate; this is the reference-style direct approach.
Main limitation: Technically demanding and still affected by dialysis conditions, calibration and laboratory procedure.^{See reference 6,See reference 8,See reference 10}

Report method: Validated calculated free testosterone
What it does: Estimates free testosterone from accurately measured total testosterone, SHBG and albumin.
Main limitation: It inherits input-assay error and equations can disagree, especially in unusual binding states.^{See reference 1,See reference 3,See reference 11}

Report method: Direct analogue immunoassay
What it does: Uses an analogue immunoassay rather than equilibrium dialysis.
Main limitation: The Endocrine Society describes common analogue free-testosterone assays as inaccurate; the word direct does not prove a reference method.^{See reference 1,See reference 12}

Report method: Free-androgen index or percent free
What it does: Reports a ratio or percentage related to total testosterone and SHBG.
Main limitation: It is not an absolute measured free-testosterone concentration; FAI can overestimate androgen exposure when SHBG is low.^{See reference 4}

Report method	What it does	Main limitation
Equilibrium dialysis, followed by a suitable testosterone measurement	Separates unbound testosterone across a membrane and measures the dialysate; this is the reference-style direct approach.	Technically demanding and still affected by dialysis conditions, calibration and laboratory procedure.^{See reference 6,See reference 8,See reference 10}
Validated calculated free testosterone	Estimates free testosterone from accurately measured total testosterone, SHBG and albumin.	It inherits input-assay error and equations can disagree, especially in unusual binding states.^{See reference 1,See reference 3,See reference 11}
Direct analogue immunoassay	Uses an analogue immunoassay rather than equilibrium dialysis.	The Endocrine Society describes common analogue free-testosterone assays as inaccurate; the word direct does not prove a reference method.^{See reference 1,See reference 12}
Free-androgen index or percent free	Reports a ratio or percentage related to total testosterone and SHBG.	It is not an absolute measured free-testosterone concentration; FAI can overestimate androgen exposure when SHBG is low.^{See reference 4}

Why free-testosterone ranges differ

Range example: The reference interval on your original report
What it shows: The laboratory's method, units and reference population.
What it must not be used for: Do not transfer it to a different method, calculator, sex, age or life stage.^{See reference 1,See reference 8}

Range example: Standardized equilibrium-dialysis study: 66–309 pg/mL for healthy nonobese men overall; 120–368 pg/mL at ages 19–39
What it shows: A carefully selected research population measured with a standardized method.
What it must not be used for: This is not a universal diagnostic cutoff, female range, treatment target or definition of optimal.^{See reference 7}

Range example: Mayo equilibrium-dialysis examples: adult men 18–69, 35–155 pg/mL; adult women 18–69, 0.1–6.4 pg/mL
What it shows: One current laboratory's method-specific reporting illustrates how intervals can differ.
What it must not be used for: Do not copy these numbers onto a result produced by another assay or calculation.^{See reference 8}

Range example: Children, puberty, pregnancy, menopause and gender-affirming therapy
What it shows: Hormone physiology and clinical questions differ across these settings.
What it must not be used for: Do not automatically apply a cisgender nonpregnant adult interval.^{See reference 4,See reference 17,See reference 18}

Range example	What it shows	What it must not be used for
The reference interval on your original report	The laboratory's method, units and reference population.	Do not transfer it to a different method, calculator, sex, age or life stage.^{See reference 1,See reference 8}
Standardized equilibrium-dialysis study: 66–309 pg/mL for healthy nonobese men overall; 120–368 pg/mL at ages 19–39	A carefully selected research population measured with a standardized method.	This is not a universal diagnostic cutoff, female range, treatment target or definition of optimal.^{See reference 7}
Mayo equilibrium-dialysis examples: adult men 18–69, 35–155 pg/mL; adult women 18–69, 0.1–6.4 pg/mL	One current laboratory's method-specific reporting illustrates how intervals can differ.	Do not copy these numbers onto a result produced by another assay or calculation.^{See reference 8}
Children, puberty, pregnancy, menopause and gender-affirming therapy	Hormone physiology and clinical questions differ across these settings.	Do not automatically apply a cisgender nonpregnant adult interval.^{See reference 4,See reference 17,See reference 18}

Convert free testosterone from pg/mL to pmol/L

Free testosterone valuepg/mL— pmol/L

Conversion changes units—not assay quality or meaning

For testosterone, 1 pg/mL equals 3.4672 pmol/L. Also, 1 ng/dL equals 10 pg/mL and 34.672 pmol/L. For example, 50 pg/mL equals 173.4 pmol/L. Preserve the original value and round only the displayed result.^{See reference 9}

This local converter sends no value for interpretation. It applies only to an absolute free-testosterone concentration. It cannot convert percent free, FAI or bioavailable testosterone; identify an assay; calculate free testosterone; apply a universal range; diagnose a condition; or choose a dose. A converted number must still use the original method-specific laboratory interval.^{See reference 1,See reference 4,See reference 8,See reference 9}

Timing and preparation details worth recording

Context: Possible male hypogonadism
Why it matters: Testosterone varies by time and day; food, glucose, sleep and acute illness can suppress results.
Responsible action: Guidelines centre repeat morning testing and generally fasting total testosterone; free testosterone is added when indicated. Avoid diagnosis during acute illness or recovery.^{See reference 1,See reference 3}

Context: Androgen excess in women
Why it matters: Low female concentrations need sensitive methods; menstrual timing and combined oral contraception can alter the result.
Responsible action: The 2025 guideline advises 8–10 AM, overnight fasting and early follicular sampling when feasible. Do not stop contraception without clinician guidance.^{See reference 4}

Context: Testosterone injection, gel, patch, pellet or tablet
Why it matters: Peak, trough and mid-interval samples answer different questions.
Responsible action: Record product, dose, route, application/injection time and collection time; follow the formulation-specific monitoring plan.^{See reference 1,See reference 17,See reference 18}

Context: Illness, energy deficit, strenuous exercise, sleep disruption, pregnancy, medicines or supplements
Why it matters: These can change production, SHBG, assay behaviour or the clinical question.
Responsible action: Record them with the result and follow the performing laboratory's specimen and supplement instructions.^{See reference 1,See reference 3,See reference 4,See reference 13}

Context	Why it matters	Responsible action
Possible male hypogonadism	Testosterone varies by time and day; food, glucose, sleep and acute illness can suppress results.	Guidelines centre repeat morning testing and generally fasting total testosterone; free testosterone is added when indicated. Avoid diagnosis during acute illness or recovery.^{See reference 1,See reference 3}
Androgen excess in women	Low female concentrations need sensitive methods; menstrual timing and combined oral contraception can alter the result.	The 2025 guideline advises 8–10 AM, overnight fasting and early follicular sampling when feasible. Do not stop contraception without clinician guidance.^{See reference 4}
Testosterone injection, gel, patch, pellet or tablet	Peak, trough and mid-interval samples answer different questions.	Record product, dose, route, application/injection time and collection time; follow the formulation-specific monitoring plan.^{See reference 1,See reference 17,See reference 18}
Illness, energy deficit, strenuous exercise, sleep disruption, pregnancy, medicines or supplements	These can change production, SHBG, assay behaviour or the clinical question.	Record them with the result and follow the performing laboratory's specimen and supplement instructions.^{See reference 1,See reference 3,See reference 4,See reference 13}

Total testosterone, SHBG and free testosterone patterns

Pattern: Low total testosterone, low SHBG, free testosterone less reduced or within the local interval
Possible context: Obesity, insulin resistance, hypothyroidism, some medicines or other low-SHBG states can lower total testosterone disproportionately.
What it does not prove: It neither rules in nor rules out hypogonadism without symptoms, repeat testing and cause evaluation.^{See reference 1,See reference 3}

Pattern: Total testosterone near normal, high SHBG, low free testosterone
Possible context: Estrogen exposure, hyperthyroidism, some liver conditions, HIV or anticonvulsants may raise SHBG.
What it does not prove: It does not identify the cause or automatically justify testosterone treatment.^{See reference 1,See reference 3}

Pattern: High free testosterone with low SHBG
Possible context: Androgen exposure, obesity/insulin resistance, hypothyroidism, medicines or calculation limits may contribute.
What it does not prove: It does not prove PCOS or healthy androgen status.^{See reference 4,See reference 5}

Pattern: Result conflicts with symptoms or related hormones
Possible context: Wrong analyte/unit, analogue assay, interference, formula choice or sample timing may explain the mismatch.
What it does not prove: Repeating a different method blindly is not the same as method confirmation.^{See reference 1,See reference 8,See reference 11,See reference 12}

Pattern	Possible context	What it does not prove
Low total testosterone, low SHBG, free testosterone less reduced or within the local interval	Obesity, insulin resistance, hypothyroidism, some medicines or other low-SHBG states can lower total testosterone disproportionately.	It neither rules in nor rules out hypogonadism without symptoms, repeat testing and cause evaluation.^{See reference 1,See reference 3}
Total testosterone near normal, high SHBG, low free testosterone	Estrogen exposure, hyperthyroidism, some liver conditions, HIV or anticonvulsants may raise SHBG.	It does not identify the cause or automatically justify testosterone treatment.^{See reference 1,See reference 3}
High free testosterone with low SHBG	Androgen exposure, obesity/insulin resistance, hypothyroidism, medicines or calculation limits may contribute.	It does not prove PCOS or healthy androgen status.^{See reference 4,See reference 5}
Result conflicts with symptoms or related hormones	Wrong analyte/unit, analogue assay, interference, formula choice or sample timing may explain the mismatch.	Repeating a different method blindly is not the same as method confirmation.^{See reference 1,See reference 8,See reference 11,See reference 12}

What can cause low free testosterone?

Low production can originate in the testes or ovaries, or in hypothalamic and pituitary signalling. Aging, acute or chronic illness, undernutrition, major energy deficit, obesity, sleep disruption, glucocorticoids, opioids and other medicines can contribute. Exogenous testosterone or anabolic steroids can suppress the body's own LH and FSH signalling.^{See reference 1,See reference 3,See reference 15}

High SHBG can lower the free fraction even when total testosterone looks less affected. Thyroid and liver conditions, estrogen exposure, HIV and some anticonvulsants are examples. An inaccurate assay or calculation can also create an apparently low value.^{See reference 1,See reference 3,See reference 11}

Fatigue, lower libido, mood change, erectile difficulty, menstrual change and body-composition concerns are not specific to testosterone. Diagnosis in men requires compatible symptoms or signs plus consistently low accurate testosterone results; other sexes and life stages require their own clinical framework.^{See reference 1,See reference 2,See reference 4,See reference 14}

What can cause high free testosterone?

Prescribed testosterone, anabolic-androgen use, sample timing near a treatment peak and low SHBG are common interpretive possibilities. A high value may also reflect assay interference or a calculation that performs poorly in the person's binding state.^{See reference 1,See reference 11,See reference 17,See reference 18}

In women, ovarian or adrenal androgen excess can contribute. PCOS is common, but rapid progressive virilization or a severe biochemical elevation needs prompt specialist evaluation for less common ovarian or adrenal causes. Free testosterone alone does not diagnose PCOS or a tumour.^{See reference 4,See reference 5}

A high result is not proof of better health and is not a reason to increase a dose. Confirm the analyte, method, unit, laboratory interval, collection timing and related hormones before drawing a conclusion.^{See reference 1,See reference 4,See reference 8}

Situations that need a different interpretation framework

Situation: Pregnancy or possible pregnancy
Why a generic range fails: Binding proteins and physiology change, and nonpregnant intervals do not define fetal risk.
Safer question: Is there prescribed or unregulated androgen exposure, and is prompt obstetric review needed?^{See reference 4,See reference 16,See reference 17}

Situation: Trying to conceive now or later
Why a generic range fails: Exogenous testosterone can suppress intratesticular testosterone and sperm production, sometimes to azoospermia.
Safer question: What cause evaluation and fertility-preserving specialist options are appropriate before treatment?^{See reference 15}

Situation: Gender-affirming testosterone therapy
Why a generic range fails: Target framework and sampling depend on formulation, goals, clinical response and safety monitoring.
Safer question: Was the sample timed correctly, and how does it fit the agreed monitoring plan and fertility goals?^{See reference 17,See reference 18}

Situation: Children and puberty
Why a generic range fails: Concentrations and clinical questions change rapidly with developmental stage.
Safer question: Is a pediatric endocrine method and age/puberty-specific interval being used?^{See reference 8,See reference 14}

Situation	Why a generic range fails	Safer question
Pregnancy or possible pregnancy	Binding proteins and physiology change, and nonpregnant intervals do not define fetal risk.	Is there prescribed or unregulated androgen exposure, and is prompt obstetric review needed?^{See reference 4,See reference 16,See reference 17}
Trying to conceive now or later	Exogenous testosterone can suppress intratesticular testosterone and sperm production, sometimes to azoospermia.	What cause evaluation and fertility-preserving specialist options are appropriate before treatment?^{See reference 15}
Gender-affirming testosterone therapy	Target framework and sampling depend on formulation, goals, clinical response and safety monitoring.	Was the sample timed correctly, and how does it fit the agreed monitoring plan and fertility goals?^{See reference 17,See reference 18}
Children and puberty	Concentrations and clinical questions change rapidly with developmental stage.	Is a pediatric endocrine method and age/puberty-specific interval being used?^{See reference 8,See reference 14}

When symptoms or exposure need urgent care

Seek urgent care for chest pain, sudden shortness of breath, coughing blood, or a painful, swollen or warm leg while using testosterone because product labels warn about possible venous blood clots. Rapidly progressive virilization or testosterone exposure during pregnancy also needs prompt medical assessment. If gel may have transferred to a child or partner, wash exposed skin, stop further contact and obtain prompt medical advice. These warnings do not mean a free-testosterone result diagnosed the emergency.^{See reference 4,See reference 16,See reference 17}

How free testosterone may change safely

The safe goal is to identify and address the cause—not to maximize a number. Sleep, adequate energy intake, body-composition changes and management of relevant illness or medicines may improve a reversible pattern for some people, but expected effects vary and do not replace repeat diagnostic testing.^{See reference 1,See reference 3}

Clinician-managed testosterone can be appropriate for defined indications after accurate diagnosis, contraindication review and shared decision-making. Monitoring is formulation- and patient-specific. A free-testosterone result cannot select a dose or prove that benefits exceed fertility, blood-count, cardiovascular, prostate or exposure risks.^{See reference 1,See reference 2,See reference 15,See reference 17}

Do not self-start testosterone, anabolic steroids, hCG, SERMs, aromatase inhibitors or unverified boosters from one value. Do not stop prescribed hormones, contraception or other medicines without the prescriber; changing them can alter symptoms, fertility and the next test.^{See reference 1,See reference 4,See reference 15}

Common free-testosterone myths, corrected

Myth: Free testosterone is always better than total testosterone.
What the evidence supports: It is most useful in defined contexts such as altered SHBG or borderline total testosterone. The full pattern and clinical question matter.^{See reference 1,See reference 3}

Myth: A direct free-testosterone result must use equilibrium dialysis.
What the evidence supports: Direct can describe an analogue immunoassay. Read the named methodology; the Endocrine Society discourages inaccurate analogue assays.^{See reference 1,See reference 12}

Myth: One low result proves I need testosterone treatment.
What the evidence supports: Diagnosis requires symptoms or signs, accurate testing and confirmation; cause, fertility and safety must be evaluated before treatment.^{See reference 1,See reference 2,See reference 15}

Myth: FAI or percent free is the same as free testosterone.
What the evidence supports: They are ratios or percentages, not an absolute measured free-testosterone concentration; FAI becomes unreliable in some low-SHBG states.^{See reference 4}

Myth: A unit converter can tell me whether the result is normal.
What the evidence supports: Conversion changes units only. Method, reference population, timing and laboratory interval still determine interpretation.^{See reference 8,See reference 9}

Myth: Higher free testosterone is always healthier.
What the evidence supports: A high result may reflect treatment timing, low SHBG, androgen excess, assay error or unsafe exposure and is not a universal performance target.^{See reference 1,See reference 4,See reference 17}

Myth	What the evidence supports
Free testosterone is always better than total testosterone.	It is most useful in defined contexts such as altered SHBG or borderline total testosterone. The full pattern and clinical question matter.^{See reference 1,See reference 3}
A direct free-testosterone result must use equilibrium dialysis.	Direct can describe an analogue immunoassay. Read the named methodology; the Endocrine Society discourages inaccurate analogue assays.^{See reference 1,See reference 12}
One low result proves I need testosterone treatment.	Diagnosis requires symptoms or signs, accurate testing and confirmation; cause, fertility and safety must be evaluated before treatment.^{See reference 1,See reference 2,See reference 15}
FAI or percent free is the same as free testosterone.	They are ratios or percentages, not an absolute measured free-testosterone concentration; FAI becomes unreliable in some low-SHBG states.^{See reference 4}
A unit converter can tell me whether the result is normal.	Conversion changes units only. Method, reference population, timing and laboratory interval still determine interpretation.^{See reference 8,See reference 9}
Higher free testosterone is always healthier.	A high result may reflect treatment timing, low SHBG, androgen excess, assay error or unsafe exposure and is not a universal performance target.^{See reference 1,See reference 4,See reference 17}

A practical next-step checklist

Keep the original value, unit, laboratory interval, named method, specimen, date and collection time together.^{See reference 1,See reference 8,See reference 9}
Confirm whether the result was measured by equilibrium dialysis, calculated with a named equation, or produced by an analogue immunoassay.^{See reference 1,See reference 6,See reference 11,See reference 12}
Review total testosterone, SHBG and albumin alongside symptoms and, when clinically relevant, LH, FSH, prolactin, estradiol and thyroid results.^{See reference 1,See reference 3,See reference 4}
Record fasting status, acute illness, sleep, exercise, supplements, every hormone medicine and exact injection or gel timing.^{See reference 1,See reference 3,See reference 4,See reference 13}
Use repeat comparable testing rather than treating one discordant value as a diagnosis, especially when method or SHBG may explain it.^{See reference 1,See reference 2,See reference 3}
Discuss fertility, pregnancy possibility and secondary gel exposure before any treatment change, and use urgent care for the warning symptoms above.^{See reference 15,See reference 16,See reference 17}

See free testosterone beside the results that give it context

Upload an existing report to organize free testosterone with total testosterone, SHBG, albumin and related hormone, thyroid, liver and blood-count results where present. LongevityMate helps you see the pattern and prepare questions to discuss—it does not diagnose a hormone disorder, assess fertility or prescribe treatment.

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Questions people ask about free testosterone

What is a normal free testosterone level?

There is no universal range. Use the age-, sex- and method-specific interval printed by the performing laboratory. Equilibrium dialysis, validated calculations and analogue immunoassays can produce different distributions. Published male intervals and a commercial laboratory's range are useful context only, not personal targets or cutoffs for another method.^{See reference 1,See reference 7,See reference 8}

Is free testosterone more important than total testosterone?

Not always. Total testosterone is central to many diagnostic pathways. Free testosterone adds information when total testosterone is near a boundary or SHBG is altered. Symptoms, repeat testing, method and related hormones still matter.^{See reference 1,See reference 3}

What is the best free-testosterone test?

Equilibrium dialysis with a suitable high-quality testosterone measurement is the reference-style direct approach. A validated calculation can be useful when total testosterone, SHBG and albumin are accurate. Common direct analogue immunoassays are not equivalent and are discouraged for clinical decisions.^{See reference 1,See reference 6,See reference 8,See reference 11,See reference 12}

Do I need to fast or test in the morning?

Follow the ordering laboratory and clinical protocol. In men evaluated for hypogonadism, guidelines centre repeat morning and generally fasting total-testosterone testing, adding free testosterone when indicated. In women evaluated for androgen excess, 2025 guidance advises 8–10 AM, overnight fasting and early follicular timing when feasible. Acute illness and hormone-treatment timing also matter.^{See reference 1,See reference 3,See reference 4}

Can SHBG make free and total testosterone disagree?

Yes. High SHBG can preserve or raise total testosterone while lowering the free fraction; low SHBG can lower total testosterone while free testosterone is less reduced. The pattern does not diagnose the cause, and a calculation inherits error from total testosterone, SHBG, albumin and the equation.^{See reference 1,See reference 3,See reference 11}

What causes low free testosterone?

Potential contexts include reduced testicular or hypothalamic-pituitary production, aging, illness, undernutrition, obesity, sleep disruption, high SHBG, medicines and suppression from exogenous androgens. Assay or formula error can mimic a low result. One value does not diagnose hypogonadism or identify the cause.^{See reference 1,See reference 3,See reference 15}

What causes high free testosterone in women?

PCOS, prescribed or unregulated androgens, low SHBG and ovarian or adrenal androgen excess can contribute. Rapid progressive virilization or severe biochemical elevation needs prompt specialist evaluation. Free testosterone alone does not diagnose PCOS or a tumour.^{See reference 4,See reference 5}

How do I convert pg/mL, ng/dL and pmol/L?

For testosterone, 1 pg/mL equals 3.4672 pmol/L; 1 ng/dL equals 10 pg/mL and 34.672 pmol/L. Keep the original analyte, value and method. Do not use an absolute-concentration converter for percent free, FAI or bioavailable testosterone, and do not apply another method's range after conversion.^{See reference 9}

Does one low free-testosterone result mean I need TRT?

No. In men, guideline diagnosis requires compatible symptoms or signs and consistently low accurate results, followed by cause and safety evaluation. Testosterone can suppress fertility and has monitoring and exposure risks. Other sexes and life stages require different clinical frameworks.^{See reference 1,See reference 2,See reference 15,See reference 17}

Can supplements interfere with the result?

Some immunoassays use biotin-streptavidin chemistry, and high-dose biotin can produce misleading results in a method-dependent direction. Disclose hair, skin and nail supplements and follow the performing laboratory's instructions. Do not assume every equilibrium-dialysis or LC-MS/MS result is affected.^{See reference 12,See reference 13}

Testosterone unit converterConvert a reported total or free testosterone value between the matching units, with explicit free ng/dL modes, transparent factors and no reference-range interpretation.

References

1. Testosterone Therapy in Men With Hypogonadism: Clinical Practice Guideline
Endocrine Society / Journal of Clinical Endocrinology & Metabolism2018-05Guideline
2. Statement on Testosterone Replacement Therapy
Endocrine Society2026-07-16Official guidance
3. Standardising the Biochemical Confirmation of Adult Male Hypogonadism: Joint Position Statement
Society for Endocrinology and Association for Laboratory Medicine2023-06-30Guideline
4. Clinical Practice Guideline for the Evaluation of Androgen Excess in Women
Society for Endocrinology2025-05-13Guideline
5. Recommendations From the 2023 International Evidence-based Guideline for PCOS
International PCOS Network2023-08-14Guideline
6. Development of a Candidate Reference Measurement Procedure for Free Testosterone
Clinical Chemistry2021-05Evidence review
7. Reference Intervals for Free Testosterone in Adult Men Measured Using a Standardized Equilibrium Dialysis Procedure
Andrology2023-01Observational study
8. Testosterone, Free, Serum by Equilibrium Dialysis (TGRP)
Mayo Clinic Laboratories2026-08Official guidance
9. SI Unit Conversion Guide
Mayo Clinic Laboratories2026-08Official guidance
10. Testosterone, Total, Bioavailable, and Free, Serum (TTBS)
Mayo Clinic Laboratories2026-08Official guidance
11. A Critical Evaluation of Simple Methods for the Estimation of Free Testosterone in Serum
Journal of Clinical Endocrinology & Metabolism2010-05Observational study
12. Testosterone, Free, Direct, With Total Testosterone
Labcorp2026-08Official guidance
13. Biotin, Serum (BIOT)
Mayo Clinic Laboratories2026-08Official guidance
14. Testosterone Levels Test
MedlinePlus2024-10-07Official guidance
15. Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline Part II
American Society for Reproductive Medicine2021-01Guideline
16. Testosterone Cypionate Injection Prescribing Information
DailyMed, US National Library of Medicine2025-08Official guidance
17. Testosterone Gel 1.62% Prescribing Information
DailyMed, US National Library of Medicine2025-08-25Official guidance
18. Standards of Care for the Health of Transgender and Gender Diverse People, Version 8
World Professional Association for Transgender Health2022-09-06Guideline

Editorial transparency

Published by: LongevityMate Editorial Team
Published: 2026-08-21
Updated: 2026-08-21

Medical disclaimer

Educational information only. This guide does not diagnose hypogonadism, PCOS, an ovarian, adrenal, testicular or pituitary condition; define a personal testosterone target; assess fertility; or decide whether testosterone treatment is safe. Use the original report and advice from a qualified health professional who knows your symptoms, sex, age, life stage, pregnancy and fertility plans, medicines, assay method, examination and history.

Evidence and editorial policy Methodology AI limitations

Free Testosterone Test: Ranges, Low and High Results, Methods and What It Means

What does a free testosterone result mean?

What does a free testosterone result mean?

Six points that prevent most free-testosterone mistakes

Free, total, bioavailable and calculated testosterone are different

How free testosterone is measured or estimated

Why free-testosterone ranges differ

Convert free testosterone from pg/mL to pmol/L

Conversion changes units—not assay quality or meaning

Timing and preparation details worth recording

Total testosterone, SHBG and free testosterone patterns

What can cause low free testosterone?

What can cause high free testosterone?

Situations that need a different interpretation framework

When symptoms or exposure need urgent care

How free testosterone may change safely

Common free-testosterone myths, corrected

A practical next-step checklist

See free testosterone beside the results that give it context

Questions people ask about free testosterone

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References

Editorial transparency

Medical disclaimer

Convert free testosterone from pg/mL to pmol/L

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