thyroid gland
Enable an AI agent to recognise a thyroid gland, assess its structural and endocrine state, and identify evidence and clinical authority needed for observation or intervention.
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 recognise a thyroid gland, assess its structural and endocrine state, and identify evidence and clinical authority needed for observation or intervention.
The thyroid gland is a bilobed endocrine organ in the anterior visceral compartment of the neck, applied to the larynx and upper trachea, whose follicular epithelium organifies iodide into thyroxine (T4) and triiodothyronine (T3) stored in colloid, while parafollicular C cells secrete calcitonin.
It can be Reconcile examination, imaging and pathology evidence to locate and identify thyroid tissue.; Compare gland and nodule measurements across time while checking that methods and targets match.; Interpret linked thyroid tests within assay, host and treatment context and flag unresolved discordance.; Assemble evidence for clinician review of diffuse abnormalities, nodules or local compression.; Identify missing prerequisites for proposed sampling, treatment or surveillance.; Track anatomical and functional consequences of authorised thyroid-directed care..
Distinguishing features
Establish thyroid tissue identity using anatomical, imaging or pathological evidence; a neck mass alone does not identify a thyroid gland.
Distinguish thyroid tissue from adjacent parathyroid tissue through tissue-specific evidence rather than proximity or a shared name.
Distinguish the endocrine gland from thyroid cartilage by identifying glandular tissue rather than a laryngeal skeletal structure.
Distinguish the whole gland from a thyroid nodule, cyst or tumour by recording the lesion's containment and the surrounding gland.
Do not exclude thyroid identity solely because tissue is outside the usual neck location or the gland has an atypical or surgically altered configuration.
Scope
+ Identification of thyroid tissue, including ectopic tissue and postoperative remnants
+ Gland location, lobar configuration, dimensions and relationships to adjacent structures
+ Thyroid hormone function interpreted through linked laboratory and clinical evidence
+ Diffuse enlargement, inflammation and focal lesions as states or parts of the gland
+ Effects of thyroid-directed treatment and constraints on further investigation or intervention
- Parathyroid glands and systemic calcium regulation
- Pituitary and hypothalamic organs and their independent disorders
- Whole-organism metabolic, cardiovascular and reproductive state
- Independent disease models for thyroid cancer, Graves' disease and other diagnoses
- Drug products, imaging equipment and clinical procedure execution
- Thyroid hormone molecules as independently modelled substances
Characteristics
- Organism and species
- Host organism identifier and species Determines which anatomical expectations and physiological reference ranges apply.
- Tissue presence and distribution
- Normally located, ectopic, mixed distribution, residual, documented absent, not visualised or uncertain Separates established absence from an examination that failed to locate tissue.
- Lobar configuration
- Observed lobes, isthmus and accessory components, with congenital or surgical explanation where known Supports recognition and interpretation of unusual or altered anatomy.
- Gland dimensions and volume
- Dimensions in mm; volume in mL; method, component and examination date Allows assessment of enlargement, asymmetry and change using comparable measurements.
- Thyroid function evidence
- TSH in mIU/L; free T4 and T3 in reported assay units; specimen time and laboratory reference intervals Supports functional interpretation while preserving assay and timing context.
- Attributed functional state
- Euthyroid, hypothyroid, hyperthyroid, discordant or undetermined; interpretation date and treatment context Separates measured circulating hormone status from conclusions about the gland's own activity.
- Parenchymal appearance
- Reported echogenicity, homogeneity and vascularity with examination method Captures diffuse tissue changes without equating an imaging pattern with a confirmed diagnosis.
- Focal lesion inventory
- Linked lesions with stable identities, locations, dimensions and assessment dates Prevents confusion between nodules during surveillance or sampling.
- Local compression or extension
- Observed, suspected, absent on specified assessment or unassessed; affected adjacent structure Records local consequences that hormone tests do not describe.
- Thyroid-directed treatment history
- Linked medication, surgery, radioiodine or ablation events with dates and anatomical targets Explains altered anatomy and function and constrains interpretation of subsequent observations.
Also called
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.
Thyroid identity and anatomy Establish which tissue belongs to the gland and how that tissue is distributed.
Location alone cannot resolve ectopic tissue, neighbouring neck structures or postoperative anatomy.
Tissue identification
Bind the gland to its host and record evidence supporting thyroid identity.
Supported thyroid identity
Record the observed tissue, identification method and unresolved alternatives.
- Which organism and species contain this gland, and what evidence identifies the tissue as thyroid? definition
- Which examination, image or pathology report supports identification, and which alternatives remain unresolved? provenance
Anatomical distribution
Describe gland components, ectopic tissue, remnants and local boundaries.
Mapped thyroid components
Record observed components and distinguish missing, removed and unobserved tissue.
- Where are the observed lobes, isthmus, accessory tissue or remnants, and what are their dimensions? measurement
- Which apparent boundaries or absent components are established, and which remain uncertain because of limited examination? boundary
Thyroid endocrine function Represent circulating hormone evidence and its interpretation in relation to the gland.
Anatomical appearance and endocrine performance require separate evidence.
Biochemical observations
Retain laboratory results with their measurement context.
Interpretable thyroid tests
Record TSH and relevant T4 or T3 results, units, intervals and collection context. These are established thyroid assessment tests. [NIDDK thyroid tests](https://www.niddk.nih.gov/health-information/diagnostic-tests/thyroid).
- What TSH, free or total T4, and T3 results are available, with specimen dates, units and assay-specific reference intervals? measurement
- What pregnancy, illness, medication, supplement or assay-interference context was documented when these samples were obtained? provenance
Functional attribution
Separate observed hormone status from its proposed origin.
Gland function interpretation
Record the attributed functional state and competing explanations without treating blood concentrations as direct measurements of gland secretion.
- What evidence supports the assigned functional state, and are laboratory results and clinical observations concordant? definition
- How has interpretation distinguished gland production from hormone release, administered hormone or altered upstream regulation? boundary
Thyroid tissue and lesions Describe diffuse tissue changes and individually tracked focal abnormalities.
A gland-level assessment must preserve the distinction between diffuse disease and lesions with different evidence or management needs.
Diffuse parenchymal state
Record enlargement, tissue appearance and evidence of inflammatory or autoimmune involvement.
Diffuse change assessment
Keep physical, imaging, antibody and diagnostic interpretations distinguishable.
- What measurements or observations establish diffuse enlargement, altered tissue appearance or tenderness? measurement
- Which evidence supports an inflammatory or autoimmune interpretation, and who made that interpretation? provenance
Focal lesion assessment
Maintain lesion identity across imaging, sampling and follow-up.
Traceable nodule evidence
Link each lesion's imaging features and any sampling result to the same target. Ultrasound and, when indicated, biopsy contribute to nodule evaluation. [American Thyroid Association thyroid nodules](https://www.thyroid.org/thyroid-nodules/).
- For each lesion, what are its location, dimensions, composition and reported ultrasound risk category, including the classification system and version? measurement
- Which lesion was sampled, what was the specimen adequacy and reported interpretation, and does that result resolve or leave uncertainty about that lesion? provenance
Thyroid local effects and course Represent effects on neighbouring structures and meaningful changes over time.
Local consequences and evolving abnormalities can require assessment independently of endocrine state.
Adjacent structure effects
Relate gland enlargement or lesions to the airway, swallowing structures, voice function and regional tissues.
Local impact attribution
Record symptoms and anatomical findings separately, then preserve the evidence connecting them.
- What breathing, swallowing or voice changes and what compression, displacement or extension findings have been documented? measurement
- What evidence attributes these effects to the thyroid, and which findings require urgent clinical assessment under the applicable pathway? action
Longitudinal thyroid change
Compare anatomical and functional observations while preserving comparability and timing.
Supported state transition
Distinguish measured progression or recovery from changed methods, unmatched lesions or transient observations.
- How have gland volume, individual lesions and thyroid test results changed across dated, comparable assessments? measurement
- Which changes followed treatment or another documented exposure, and how strong is the evidence for attribution? provenance
Thyroid investigation and intervention Record the evidence, constraints and follow-up required for thyroid-directed care.
A proposed action depends on the specific thyroid question, remaining tissue, host context and authorised clinical plan.
Investigation selection
Connect proposed laboratory tests, imaging or sampling to a defined unresolved question.
Justified next investigation
Record why an investigation is proposed, what it could resolve and which prerequisites remain unmet.
- What unresolved functional or structural question would the proposed thyroid test, scan or biopsy answer? action
- What patient-specific constraints, prior iodine exposure, pregnancy or lactation context, target confirmation and clinical authorisation must be checked for this investigation? action
Treatment and residual capacity
Record thyroid-directed treatment decisions and their effects on remaining anatomy and function.
Authorised care and follow-up
Link observation, medication, ablation or surgery to its clinical indication, responsible professional and subsequent reassessment.
- What thyroid-directed plan has been authorised, for which indication and target, and with what documented constraints involving adjacent structures or host condition? action
- What thyroid tissue and functional capacity remain after treatment, and what monitoring or hormone replacement plan has been documented? 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.
- Typical cervical thyroid (two lateral lobes joined by an isthmus)
- Thyroid with a pyramidal lobe (Lalouette)
- Hemiagenesis or marked hypoplasia (most often the left lobe)
- Lingual thyroid
- Other ectopic thyroid (e.g. suprahyoid, mediastinal, or lateral aberrant tissue)
- Diffuse goitrous thyroid
- Nodular or multinodular thyroid
- Post-surgical remnant in the thyroid bed
- Which of these kinds and varieties hold for the sense of thyroid gland 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 - Q16399 - Item for the thyroid gland as an anatomical organ.
- Foundational Model of Anatomy (FMA) - 9603 - FMAID for thyroid gland.
- UBERON - UBERON:0002046 - Uber-anatomy ontology class thyroid gland.
- MeSH - D013961 - Heading Thyroid Gland.
- SNOMED CT - 69748006 - Thyroid structure (body structure).
- Terminologia Anatomica - A06.2.02.001 - Glandula thyroidea in TA98-style coding; TA2 uses a numeric identifier for the same concept.
- ICD-O topography - C73.9 - Thyroid gland as a tumour site, not a code for the normal organ.
- Which of these identifiers and schemes hold for the sense of thyroid gland 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.
- Terminologia Anatomica - FIPAT / International Federation of Associations of Anatomists (IFAA)
- 2015 ATA nodule and differentiated-thyroid-cancer guidelines (and related ATA hypo-/hyperthyroidism statements) - American Thyroid Association
- WHO Classification of Tumours, endocrine/neuroendocrine volume - IARC / World Health Organization
- The Bethesda System for Reporting Thyroid Cytopathology - originating from NCI-sponsored conferences; used as the reporting standard for thyroid FNA
- ACR TI-RADS - American College of Radiology; EU-TIRADS - European Thyroid Association; K-TIRADS - Korean Society of Thyroid Radiology (competing ultrasound risk systems)
- Iodine-deficiency control and salt iodization recommendations - WHO, UNICEF, and the Iodine Global Network
- Neonatal screening for congenital hypothyroidism - national public-health programmes (not a single global statute)
- Medical use of radioiodine as a radioactive drug/source - national radiation and medicines regulators (e.g. US NRC/FDA; equivalent EU competent authorities); dose-constraint guidance from ICRP
- Which of these standards and regulation hold for the sense of thyroid gland 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.
- Palpated on physical examination of the anterior neck and imaged with high-frequency ultrasound as the first-line structural test.
- Sampled by fine-needle aspiration of nodules; resected by hemi- or total thyroidectomy, after which remnant tissue is followed in the thyroid bed.
- Mapped physiologically with 99mTc-pertechnetate or 123I scintigraphy and treated with 131I for hyperthyroidism or remnant ablation.
- Screened in newborns by dried-blood-spot TSH (or T4) programmes to detect congenital hypothyroidism.
- Examined histologically after surgery or autopsy; dissected as a standard neck structure in anatomy teaching.
- A common clinical target in veterinary medicine, especially feline hyperthyroidism.
- Which of these real-world use hold for the sense of thyroid gland 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.
- Adult gland mass - 15-25 - g
- Adult ultrasound volume (iodine-sufficient populations) - about 8-18 in women, 10-25 in men; upper reference often cited near 18 (women) and 25 (men) - mL
- Serum TSH (typical adult laboratory reference; method- and lab-dependent; pregnancy ranges differ) - 0.4-4.0 - mIU/L
- Serum free T4 (typical adult reference; method-dependent) - 10-25 - pmol/L
- Median urinary iodine (WHO: adequate iodine nutrition in a population) - 100-199 - µg/L
- Recommended iodine intake (adult, non-pregnant; WHO) - 150 - µg/day
- 24-hour radioiodine uptake (euthyroid, iodine-sufficient adults; diet and assay dependent) - about 10-30 - %
- Which of these typical measurements hold for the sense of thyroid gland 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.
- Autoimmune destruction (Hashimoto thyroiditis) causing hypothyroidism; TSH-receptor stimulation (Graves disease) causing hyperthyroidism.
- Nodules and carcinoma of follicular-cell lineage (papillary, follicular, oncocytic, poorly differentiated, anaplastic) or of C-cell lineage (medullary).
- Diffuse or nodular goitre with compressive airway, oesophageal or venous obstruction.
- Thyroid storm and myxoedema coma as life-threatening decompensations of hyper- and hypothyroidism.
- Congenital dysgenesis or dyshormonogenesis causing neonatal hypothyroidism if untreated.
- Iodine deficiency (endemic goitre, cretinism historically) and iodine excess or drugs (amiodarone, lithium) disrupting hormone synthesis.
- Childhood ionizing-radiation exposure raising later thyroid-cancer risk; radioiodine therapy and neck irradiation as iatrogenic exposures.
- Operative injury to a recurrent laryngeal nerve or to parathyroid glands (hypoparathyroidism), and rare airway catastrophe from haemorrhage into a goitre.
- Which of these failure modes and hazards hold for the sense of thyroid gland 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.
- Endemic goitre remains a public-health pattern in iodine-poor highland and inland belts (Himalaya, Andes, parts of Africa; historically Alpine Europe); coastal East Asia has high dietary iodine and a different mix of nodules and autoimmunity.
- Toxic multinodular goitre is relatively more common where iodine deficiency was long-standing; Graves disease dominates thyrotoxicosis in iodine-replete North America.
- English goitre/goiter versus German and Central European Struma for the enlarged gland; US goiter versus UK goitre.
- Ultrasound risk stratification follows ACR TI-RADS in much of North America, EU-TIRADS in Europe, and K-TIRADS in Korea, so the same nodule can be labelled differently.
- Mandatory salt iodization and neonatal TSH screening exist in many states but not uniformly; cut-offs and follow-up protocols are national.
- Which of these regional variation hold for the sense of thyroid gland 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.
- Parathyroid glands - Lie posterior (or occasionally within) the thyroid; distinguished by PTH secretion and, on histology/IHC, PTH rather than thyroglobulin/TTF-1; clinically by calcium and PTH, and by sestamibi or PTH washout of an FNA.
- Thyroid cartilage - Laryngeal hyaline skeleton sharing the name 'thyroid'; it is ossifying cartilage on imaging, not a follicular endocrine organ, and has no colloid or thyroid hormones.
- Cervical lymph node - A node has a fatty hilum and is outside the thyroid capsule; a thyroid nodule is intraparenchymal. Cytology and, if needed, thyroglobulin washout versus lymphoid markers separate them.
- Thyroglossal duct cyst - Midline cystic remnant along the embryonic descent path, often moving with tongue protrusion and related to the hyoid; not functioning follicular parenchyma unless it contains ectopic thyroid tissue (isotope scan / ultrasound).
- Pyramidal lobe versus Delphian (prelaryngeal) node - Pyramidal lobe is thyroid parenchyma in continuity with the isthmus toward the hyoid; a Delphian node is lymphoid tissue anterior to the larynx and is separated by ultrasound continuity and, if resected, histology.
- Thymus - Anterior mediastinal lymphoid/epithelial organ of a different embryonic origin; not continuous with the cervical thyroid on imaging and not thyroglobulin-producing.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of thyroid gland this model covers, and on what evidence? provenance
Sources
- Gray's Anatomy: The Anatomical Basis of Clinical Practice (thyroid gland) - Position in the anterior neck, lobes/isthmus/pyramidal lobe, relations to trachea, strap muscles and recurrent laryngeal nerves, and adult mass.
- Terminologia Anatomica (glandula thyroidea) - Standard anatomical name and place of the organ in the official anatomical nomenclature issued by FIPAT/IFAA.
- 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer - How the gland is encountered clinically (nodules, ultrasound, FNA, surgery, radioiodine) and the ATA as the issuing body for nodule/cancer practice.
- WHO Classification of Tumours: Endocrine and Neuroendocrine Tumours - Pathological kinds of thyroid neoplasia (follicular-cell vs C-cell lineages) used in histopathology practice.
- Assessment of iodine deficiency disorders and monitoring their elimination - Population iodine status, urinary iodine ranges, goitre as a public-health finding, and salt-iodization policy.
- Wikidata item Q16399 (thyroid gland) - Stable public identifier and crosswalks to FMA, UBERON, MeSH and related anatomy codes.
What the second pass must settle
- Does this registry entry cover thyroid glands across vertebrate species, and which species-specific anatomical and functional extensions are required?
- Which age-, species-, pregnancy- and assay-specific reference sources should govern interpretation of gland size and thyroid tests?
- Which jurisdiction and version of nodule imaging, cytology and management guidance should govern risk labels and action thresholds?
- How should ectopic thyroid tissue and postoperative remnants share organ identity, and when should a lesion or removed specimen become a separately linked thing?
- What coverage is required for congenital thyroid disorders and C-cell or calcitonin-related assessment beyond the provisional follicular-function emphasis?