testosterone
Enable an AI agent to identify testosterone, assess the reliability and condition of a particular occurrence, and determine which measurement, handling or use actions its evidence supports.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to identify testosterone, assess the reliability and condition of a particular occurrence, and determine which measurement, handling or use actions its evidence supports.
Testosterone is the principal circulating C19 androgen (17β-hydroxyandrost-4-en-3-one) secreted mainly by testicular Leydig cells, with lesser ovarian-theca and adrenal production, that signals through the androgen receptor and, after 5α-reduction or aromatization, through dihydrotestosterone and estradiol pathways to drive male sexual differentiation, secondary sex characteristics, support of spermatogenesis, and anabolic effects on muscle, bone and red-cell mass.
It can be Resolve a testosterone label against a stereochemical reference and flag unresolved related compounds.; Normalize testosterone quantities while preserving matrix, fraction, units and derivative-equivalence assumptions.; Select or request an identity or quantification method suitable for the matrix and expected concentration.; Assess a specimen, reference standard or material lot for a specified analytical or handling purpose.; Trace binding, conversion and origin claims to supporting observations and neighbouring models.; Route proposed handling or use through the applicable product, laboratory or clinical authority..
Distinguishing features
Match the complete stereochemical structure, rather than the name or molecular formula alone: testosterone is the 17β-hydroxy, 3-oxo steroid with a C4-C5 double bond. [PubChem testosterone identity](https://pubchem.ncbi.nlm.nih.gov/compound/Testosterone)
Require identity evidence capable of resolving the relevant neighbouring steroid, including epitestosterone, dihydrotestosterone or androstenedione, before treating an analytical signal as testosterone.
Check whether the named material is unesterified testosterone, a testosterone ester or a formulation containing either; record any testosterone-equivalent quantity separately from the actual compound quantity.
Distinguish a testosterone molecule or material from a reported testosterone result: total, free and other operationally defined fractions must retain their measurement definitions.
Separate molecular identity from origin: identifying testosterone does not by itself establish whether it was produced biologically or introduced.
Scope
+ Molecular identity and evidence distinguishing testosterone from related steroids
+ Occurrences in biological specimens, reference materials, bulk substances and formulations
+ Amount, concentration, purity and the basis on which each is reported
+ Biological binding fraction and evidence about endogenous or introduced origin
+ Material integrity, analytical suitability and supported handling or use decisions
- Diagnosis and management of endocrine conditions
- Patient-specific prescribing, dosing and treatment monitoring
- Whole-organism endocrine regulation and reproductive development
- Complete models of testosterone esters, metabolites and other androgens
- Finished medicinal product manufacture, delivery-device operation and inventory
- Determination of a person's sex, gender, fertility or athletic eligibility
Characteristics
- Molecular identity evidence
- Reference structure and identifiers linked to identity-test evidence Prevents related steroids, derivatives or ambiguous labels from being accepted as testosterone.
- Occurrence context
- Bulk substance; reference material; biological specimen; formulation constituent; other specified matrix Determines which measures of condition and suitability apply.
- Chemical form represented
- Unesterified testosterone; linked derivative; testosterone-equivalent reporting; unresolved Prevents substitution of derivative mass or product strength for testosterone amount.
- Amount or concentration
- Amount in mol or mg; concentration in nmol/L, ng/dL or a stated matrix-appropriate unit Supports comparison and accounting only when matrix, denominator and analyte basis are explicit.
- Reported biological fraction
- Total; free; bioavailable with explicit definition; specified bound fraction; unspecified; not applicable Prevents unlike testosterone measurements from being treated as interchangeable.
- Measurement uncertainty and limits
- Uncertainty in result units or percent; detection and quantification limits in result units Distinguishes a supported quantity from an estimate, an upper bound or an uninterpretable signal.
- Testosterone purity or content
- Mass fraction or percent with assay basis; chromatographic area percent recorded separately Separates actual testosterone content from nominal material mass and method-dependent purity indicators.
- Binding context
- Links to SHBG, albumin and other specified binding observations or calculation inputs Makes biological fraction assignments and calculated results traceable.
- Origin attribution
- Endogenous supported; introduced supported; mixed supported; unresolved Prevents source attribution from being inferred solely from identity or concentration.
- Integrity and suitability
- Supported for specified use; assessment pending; compromised; rejected Connects storage, contamination and analytical evidence to a concrete intended action.
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Testosterone identity Establish what chemical entity a testosterone reference actually denotes.
Steroid names, shared structural features and derivative labels are insufficient to establish testosterone identity.
Stereochemical recognition
Resolve the claimed substance against a complete testosterone reference structure.
Identity supported
Record the reference identity, observed evidence and remaining chemical ambiguity.
- Which stereochemical structure and authoritative identifiers define testosterone in this record? definition
- What evidence distinguishes this occurrence from epitestosterone, dihydrotestosterone, androstenedione and other plausible interferents? measurement
Parent and derivative boundary
Separate testosterone itself from linked derivatives and testosterone-equivalent reporting.
Chemical form resolved
Identify the actual compound represented by a label or quantity without creating an unsupported registry split.
- Does the record denote unesterified testosterone, an ester, another derivative or a mixture containing testosterone? boundary
- If a quantity is expressed as testosterone equivalent, which actual compound, conversion basis and evidence support it? provenance
Testosterone occurrence Locate the substance in a specific material or biological setting and qualify its attributed origin.
The same identity requires different interpretation in a serum specimen, a reference solution and a medicinal formulation.
Matrix and carrier
Specify where testosterone occurs and what the record's quantity describes.
Occurrence anchored
Link testosterone to its specimen, lot or formulation and preserve the relevant sampling context.
- Which specimen, material lot or formulation contains the testosterone, and in which matrix or carrier? provenance
- Does the quantity describe the original material, a sampled aliquot, an extract or a prepared dilution? measurement
Origin evidence
Represent biological production or introduction as an evidence-dependent attribution.
Origin qualified
Separate established identity from claims about how testosterone entered the material or organism.
- What manufacturing, administration, sampling or analytical evidence supports the claimed origin of this testosterone? provenance
- Can the available evidence distinguish endogenous, introduced and mixed contributions, or must origin remain unresolved? boundary
Testosterone measurement Define the measured quantity and establish whether the result is analytically usable.
Testosterone results can differ in fraction, preparation, method and reporting basis even when their labels appear identical.
Measurand and fraction
Make the testosterone quantity, biological fraction and preparation basis explicit.
Quantity defined
Preserve what was measured and distinguish direct observations from calculated values.
- Is the result total testosterone, free testosterone, explicitly defined bioavailable testosterone or another specified quantity? definition
- What units, matrix, preparation steps and direct-measurement or calculation basis define the reported value? measurement
Selectivity and comparability
Assess whether an assay supports identification, quantification and comparison in the stated setting.
Result qualified
Attach calibration, interference, uncertainty and comparability evidence to the testosterone result.
- What testosterone calibration traceability, matrix validation, interference assessment and quantification limits support this result? measurement
- Do fraction, method, collection time, exposure timing and reference-population context permit the proposed comparison? boundary
Testosterone biological relations Record binding and transformation relationships needed to interpret a biological occurrence.
A testosterone concentration alone does not establish its binding distribution, subsequent conversion or biological effect.
Binding distribution
Connect a testosterone fraction to the binding observations or assumptions supporting it.
Fraction evidence linked
Expose the evidence and assumptions behind free, bound or bioavailable assignments.
- Which SHBG, albumin or other binding measurements are linked to this testosterone occurrence? measurement
- If a testosterone fraction is calculated, which equation, input measurements and applicability evidence support the estimate? provenance
Conversion and effect boundaries
Link testosterone to investigated metabolites and biological responses without treating them as the same thing.
Biological inference bounded
Distinguish measured testosterone from evidence of conversion, receptor activity or downstream response.
- What evidence supports any claimed conversion involving testosterone, dihydrotestosterone or estradiol in this biological context? provenance
- Which proposed conclusions require separate metabolite, receptor, tissue or organism evidence beyond this testosterone measurement? boundary
Testosterone fitness and actions Connect material condition and applicable authority to a specific proposed action.
Identity and nominal content alone cannot establish whether testosterone material is suitable for calibration, processing, handling or medicinal use.
Content and integrity
Assess testosterone content and condition against requirements for the intended use.
Fitness supported
Record assay basis, relevant impurities and condition evidence without assuming one specification fits every occurrence.
- What testosterone content, impurity profile and acceptance specification apply to this material and intended use? measurement
- Do documented storage, preparation, container and handling conditions support continued suitability, or require reassessment? action
Use and handling authority
Resolve the prerequisites for acting on the particular testosterone material.
Next action grounded
Identify supported actions and link medicinal or regulated decisions to the models and authorities that own them.
- Which current safety information, product instructions and jurisdiction-specific requirements apply to the proposed testosterone handling or use? provenance
- Does the evidence support analysis, preparation, transfer or disposal, or require quarantine, further testing or referral to an authorised decision-maker? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Unesterified parent steroid (crystalline API, pellets, some gels)
- Injectable esters used in replacement and sport (propionate, enanthate, cypionate, undecanoate)
- Oral testosterone undecanoate (lymphatic absorption, not 17α-alkylated)
- Transdermal products (hydroalcoholic gels, solutions, patches)
- Circulating total testosterone as reported by immunoassay or LC-MS/MS
- Free testosterone (unbound) and bioavailable testosterone (free plus albumin-bound)
- Endogenous secretion versus exogenous pharmaceutical or anabolic-androgenic supply
- Isotopically labelled assay standards (for example 13C- or 2H-testosterone) used as LC-MS/MS internal standards
- Which of these kinds and varieties hold for the sense of testosterone this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata - Q131877 - Item for the parent steroid testosterone.
- CAS Registry Number - 58-22-0 - Unesterified testosterone; each ester has its own CAS number.
- PubChem CID - 6013 - NCBI compound record for testosterone.
- FDA UNII - 3XMK78S47O - Substance identifier used in U.S. product labelling.
- ATC - G03BA03 - WHO Anatomical Therapeutic Chemical code (androgens, 3-oxoandrostenes).
- InChIKey - MUMGGOZAMZWBJJ-DYKIIFRCSA-N - Standard InChIKey of 17β-hydroxyandrost-4-en-3-one.
- ChEBI - CHEBI:17347 - ChEBI identifier for testosterone.
- DrugBank - DB00624 - DrugBank drug record; esters are separate records.
- Which of these identifiers and schemes hold for the sense of testosterone this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- U.S. Controlled Substances Act / DEA: testosterone and esters are Schedule III anabolic steroids.
- FDA: approved new-drug applications and labelling for TRT products, including boxed warnings on secondary gel exposure and hematocrit/cardiovascular cautions.
- EMA and national EU agencies: marketing authorisations for testosterone replacement products (gels, injections, oral undecanoate).
- WADA Prohibited List (S1 Anabolic Agents): testosterone and its esters are prohibited in sport; urine T/E ratio and IRMS are the control methods.
- USP and Ph. Eur. monographs for testosterone and named esters (identity, assay, related substances).
- CDC Hormone Standardization (HoST) program: assay standardization and harmonized male reference interval for total testosterone.
- Endocrine Society (2018) and AUA/EAU hypogonadism guidelines: practice standards for diagnosis and monitoring, not statutes.
- UK Misuse of Drugs Act 1971: anabolic steroids including testosterone are Class C / Schedule 4 Part II.
- WHO INN: testosterone (parent) with separate INNs for esters (e.g. testosterone enantate, cypionate, undecanoate).
- Which of these standards and regulation hold for the sense of testosterone this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Morning serum total testosterone is the first-line laboratory test when adult male hypogonadism is suspected, with confirmation on a second morning sample, preferably by LC-MS/MS.
- Prescribed intramuscular esters (typically enanthate or cypionate every 1-2 weeks, or undecanoate at longer intervals) and daily transdermal gel for confirmed hypogonadism.
- Masculinizing gender-affirming hormone therapy, using the same ester and gel products at doses aimed at adult-male ranges.
- Induction of puberty in delayed puberty or hypogonadotropic hypogonadism.
- Elite-sport doping control: urinary testosterone, epitestosterone and the T/E ratio, with GC-C-IRMS when the ratio is abnormal.
- Non-medical anabolic use in bodybuilding and image-enhancement, usually as high-dose esters, often stacked with other AAS.
- Clinical-chemistry calibrators, proficiency-testing materials and isotopically labelled internal standards.
- Which of these real-world use hold for the sense of testosterone this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Harmonized total testosterone, healthy non-obese men 19-39 y (CDC-standardized LC-MS/MS) - 264-916 - ng/dL
- Same adult-male total testosterone interval in SI units - 9.2-31.8 - nmol/L
- Total testosterone, premenopausal adult women (method-dependent; LC-MS/MS preferred) - 15-70 - ng/dL
- Free testosterone, eugonadal adult men (equilibrium dialysis or valid calculation; highly method-dependent) - 5-21 - ng/dL
- Molar mass of C19H28O2 - 288.42 - g/mol
- Unbound fraction of circulating testosterone in adult men - 1-3 - %
- Plasma half-life of unesterified testosterone - 10-100 - min
- Which of these typical measurements hold for the sense of testosterone this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Secondary erythrocytosis: hematocrit commonly rises on TRT and can require dose reduction or phlebotomy.
- Reversible suppression of the hypothalamic-pituitary-gonadal axis and spermatogenesis, causing oligo/azoospermia and infertility while exposed.
- Transdermal gel transfer to partners or children, causing unintended virilization (labelled risk).
- Acne, seborrhoea and androgenetic alopecia; gynecomastia via aromatization to estradiol.
- Labelled contraindication in known prostate or male breast cancer; PSA and digital rectal exam are used for monitoring, not because T is proven to cause prostate cancer.
- Venous thromboembolism and cardiovascular-risk labelling; evidence of net CV harm at replacement doses remains contested.
- Worsening of untreated obstructive sleep apnea.
- Pulmonary oil microembolism and anaphylaxis with some intramuscular undecanoate products (U.S. Aveed REMS).
- Low-range immunoassay inaccuracy (women, children, severely hypogonadal men) versus LC-MS/MS, causing misclassification.
- Diversion and supraphysiologic AAS use: dyslipidemia, left-ventricular hypertrophy, dependence, and HPG shutdown after cessation.
- Which of these failure modes and hazards hold for the sense of testosterone this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- U.S. clinical labs conventionally report ng/dL; most of Europe, the UK and Australia report nmol/L (multiply ng/dL by 0.0347).
- Testosterone cypionate dominates U.S. clinic and compounding practice; enanthate and intramuscular undecanoate are more typical in Europe and Australia.
- Diagnostic cut-offs differ by society: Endocrine Society harmonized ~264 ng/dL (9.2 nmol/L), AUA often 300 ng/dL, some European pathways 8-12 nmol/L.
- Direct-to-consumer and cash-pay 'TRT clinic' prescribing is a large U.S. pattern; many public systems restrict treatment to documented organic hypogonadism.
- Criminal and sporting control of non-prescribed AAS is Schedule III in the U.S., Class C in the UK, and more variable elsewhere, which changes street supply and ester mix.
- Brand gels differ by market (for example AndroGel in the U.S., Testogel in much of Europe) with different concentrations and transfer-warning wording.
- Which of these regional variation hold for the sense of testosterone this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- 5α-Dihydrotestosterone (DHT) - 5α-reduced, non-aromatizable, higher androgen-receptor affinity; separate LC-MS/MS (or dedicated immunoassay) and clinical use of 5α-reductase inhibitors to lower DHT while testosterone may rise slightly.
- Androstenedione - 17-keto precursor with weak androgen activity; distinguished by C17 oxidation state on LC-MS/MS and by much lower circulating androgen-receptor occupancy.
- Epitestosterone - 17α-epimer with negligible androgen activity; doping control uses the urinary testosterone/epitestosterone (T/E) ratio, then GC-C-IRMS for carbon isotope ratio when the ratio is elevated.
- Nandrolone (19-nortestosterone) - 19-nor anabolic steroid; urinary 19-norandrosterone on GC-MS/MS, not native testosterone metabolites.
- Methyltestosterone and other 17α-alkylated androgens - 17α-methyl (or similar) substitution enables oral bioavailability but adds hepatotoxicity; mass-spectrometric 17α-alkyl fragment, not present on native testosterone.
- Dehydroepiandrosterone (DHEA) / DHEA-S - Δ5 adrenal precursor, mainly sulfated; immunoassay or LC-MS for DHEA-S, which does not track testicular Leydig output the way testosterone does.
- Estradiol - Aromatase product of testosterone; measured as E2, not T, and used to explain gynecomastia or to monitor aromatization on high-dose androgens.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of testosterone this model covers, and on what evidence? provenance
Sources
- Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline (Bhasin et al.). Journal of Clinical Endocrinology & Metabolism, Endocrine Society, 2018. - Clinical diagnosis of hypogonadism, formulation classes, monitoring (hematocrit, PSA, fertility), and major labelled risks of testosterone therapy.
- Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the United States and Europe (Travison et al.). Journal of Clinical Endocrinology & Metabolism, Endocrine Society, 2017. - CDC-standardized adult-male total-testosterone reference interval used in measurements.
- PubChem Compound Summary for CID 6013, Testosterone. National Center for Biotechnology Information, U.S. National Library of Medicine. - CAS, UNII, InChIKey, molecular formula/mass and other substance identifiers.
- World Anti-Doping Code International Standard: Prohibited List, class S1 Anabolic Agents. World Anti-Doping Agency. - Status of testosterone and its esters as prohibited anabolic agents and the doping-control context (including T/E ratio follow-up).
- Wikidata item Q131877 (testosterone). Wikimedia Foundation / Wikidata. - Crosswalk among CAS, ChEBI, DrugBank, ATC and related identifiers.
- Testosterone Information (product class page and related drug-safety communications). U.S. Food and Drug Administration. - U.S. approved uses, secondary dermal-transfer warnings, and cardiovascular/hematocrit labelling for testosterone products.
- Controlled substance schedules: anabolic steroids including testosterone and its esters, Schedule III. U.S. Drug Enforcement Administration / Controlled Substances Act. - U.S. legal control of testosterone as an anabolic steroid.
What the second pass must settle
- Does an existing Vercy world model already own testosterone, requiring this registry entry to link to it rather than receive a separate publication?
- How should isotope-labelled testosterone reference materials be represented within this entry while respecting existing registry granularity?
- Which authoritative measurement procedures and traceability requirements should govern each supported matrix and testosterone fraction?
- Which context-specific evidence is sufficient to attribute endogenous, introduced or mixed testosterone origin, and what uncertainty must remain explicit?
- Which validated storage, impurity and fitness criteria apply to each material form and intended use, and which belong in linked product or specimen models?