Hyperthyroidism

Slide 1 · Hyperthyroidism

Mechanisms, clinicopathologic effects and etiologic diagnosis

A pathology-led approach to the thyrotoxic syndrome

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Distinguish thyroid hyperfunction from other causes of thyrotoxicosis.

Explain the major systemic effects of excess thyroid hormone.

Interpret TSH, free T4, T3, uptake patterns, and Graves-associated antibodies.

Connect therapeutic interventions to their mechanistic targets.

Slide 3 · Thyrotoxicosis is a clinical hormone-excess state

Elevated circulating free thyroid hormone produces systemic hypermetabolism.

The clinical syndrome reflects excess T3/T4 action in peripheral tissues.

The source of excess hormone is not necessarily increased gland synthesis.

High circulating T3/T4

Peripheral tissue signaling

Hypermetabolism + symptoms

SCHEMATIC

Slide 4 · Hyperthyroidism is narrower than thyrotoxicosis

Hyperthyroidism: The thyroid gland synthesizes and secretes excessive hormone.

Destructive thyroiditis: Stored hormone leaks from injured follicles.

Exogenous hormone or ectopic tissue may produce thyrotoxicosis without intrinsic gland hyperfunction.

Hyperthyroidism

Increased synthesis / gland function

Other thyrotoxicosis

Release, extrathyroidal production, or ingestion

The distinction predicts uptake patterns and treatment response.

Slide 5 · Classifying the source changes the diagnostic question

First ask whether circulating hormone excess is due to new thyroid synthesis.

Then identify diffuse, nodular, pituitary-driven, destructive, or extrathyroidal mechanisms.

Symptoms establish the syndrome but rarely determine etiology alone.

Synthesis in gland

Release of stored hormone

Ectopic or exogenous supply

SCHEMATIC

Slide 6 · Follicles are the functional unit of the thyroid

Thyroid follicular epithelium surrounds a lumen containing stored colloid.

A functioning follicle synthesizes and releases thyroid hormones.

Follicular growth and colloid dynamics change across different thyroid diseases.

Follicular epithelium

Colloid (stored hormone)

SCHEMATIC

Slide 7 · The hypothalamic–pituitary–thyroid axis

Hypothalamic TRH stimulates pituitary thyrotrophs.

Pituitary TSH stimulates thyroid follicular hormone synthesis and release.

Circulating T3/T4 suppress TRH and TSH through negative feedback.

Hypothalamus: TRH

Pituitary: TSH

Thyroid: T3 and T4

Negative

Feedback

SCHEMATIC

Slide 8 · TSH receptor signaling drives hormone production

TSH binds a receptor on thyroid follicular epithelium.

Receptor activation engages G proteins and cyclic AMP signaling.

The pathway increases thyroid hormone synthesis and release.

TSH binds thyroid receptor

TSH receptor

CAMP signaling

Hormone synthesis and release

SCHEMATIC

Slide 9 · Thyroid hormones act through gene regulation

T3 and T4 enter peripheral tissues; Thyroid hormone receptors act in cell nuclei.

Hormone–receptor complexes regulate transcription of responsive genes.

Multiorgan manifestations follow altered metabolic and physiologic programs.

Circulating thyroid hormones

Nuclear thyroid hormone receptor

Target gene transcription

SCHEMATIC

Slide 10 · Three mechanistic routes to circulating hormone excess

Increased synthesis: Graves disease, toxic nodules, or excess TSH signaling.

Destructive release: Painful or painless thyroiditis releases preformed hormone.

Other supply: Ectopic thyroid tissue or ingested thyroid hormone.

Synthesis in gland

Release of stored hormone

Ectopic or exogenous supply

SCHEMATIC

Slide 11 · Primary and secondary hyperthyroidism

Primary hyperthyroidism originates in the thyroid gland.

Rare secondary hyperthyroidism can result from a TSH-secreting pituitary neuroendocrine tumor.

Primary disease generally suppresses TSH; Pituitary-driven disease may not.

Primary

Thyroid autonomy / stimulation

TSH suppressed

Secondary

TSH-secreting PitNET

TSH normal or raised

Interpret TSH in the context of concurrent free hormone levels.

Slide 12 · Principal endogenous causes

Graves disease is the predominant cause account (approximately 85%).

Other major causes are hyperfunctioning multinodular goiter and toxic adenoma.

These three mechanisms involve increased glandular hormone production.

Graves

Toxic nodule

Multinodular

Different functional distributions

SCHEMATIC

Slide 13 · Additional thyroid-hyperfunction causes

Iodine-induced hyperthyroidism is listed among primary glandular causes.

Maternal Graves disease can produce neonatal thyrotoxicosis.

Rare pituitary TSH excess produces secondary hyperthyroidism.

Primary

Iodine-related; Neonatal maternal Graves

Secondary

TSH-secreting pituitary tumor

Clinical context is needed to recognize less common causes.

Slide 14 · Causes without increased gland production

Subacute granulomatous (de Quervain) thyroiditis is typically painful.

Lymphocytic thyroiditis may be painless.

Struma ovarii and factitious thyrotoxicosis are extrathyroidal supply routes.

Release from thyroid

Painful or painless thyroiditis

Extrathyroidal source

Struma ovarii; Exogenous thyroxine

A low-uptake gland may coexist with elevated circulating hormone.

Slide 15 · Graves disease: Receptor-directed autoimmunity

Autoantibodies target the TSH receptor, mimicking TSH stimulation.

Thyroid-stimulating immunoglobulins (TSI) activate adenyl cyclase signaling.

Hypersecretion continues despite pituitary TSH suppression.

TSI / TRAb stimulates receptor

TSH receptor

CAMP signaling

Hormone synthesis and release

SCHEMATIC

Slide 16 · Graves disease: The characteristic gland

The untreated gland is usually diffusely and symmetrically enlarged.

Follicular epithelium is crowded and tall, sometimes forming small papillary projections.

Colloid margins are scalloped because hormone-producing epithelium actively resorbs colloid.

Scalloped colloid

SCHEMATIC

Slide 17 · Toxic multinodular goiter: Functional heterogeneity

Recurrent follicular hyperplasia and involution create an irregular, nodular gland.

Some nodules become functionally autonomous, while others are relatively inactive.

Radioiodine uptake is consequently patchy rather than uniform.

Heterogeneous activity

SCHEMATIC

Slide 18 · Toxic adenoma: A focal source of excess hormone

A solitary hyperfunctioning nodule can dominate hormone production.

On radionuclide imaging, uptake is increased in the functional nodule.

Pituitary TSH suppression reduces activity in surrounding thyroid tissue.

Solitary active nodule

SCHEMATIC

Slide 19 · Iodine-associated and neonatal thyrotoxicosis

Iodine-induced hyperthyroidism belongs to the increased-production group.

Neonatal thyrotoxicosis may occur with maternal Graves disease.

In both settings, history and clinical context direct etiologic interpretation.

CLINICOPATHOLOGIC LINK

These are contextual causes—not interchangeable with destructive thyroiditis.

Interpretation

Slide 20 · TSH-secreting pituitary tumors are exceptional

The source of stimulation is pituitary rather than autonomous thyroid tissue.

Serum TSH is inappropriately normal or elevated in the presence of hormone excess.

Treatment may include pituitary surgery, somatostatin analogs, or irradiation.

Pituitary TSH secretion

Thyroid TSH-receptor activation

High T3/T4 despite non-low TSH

Upstream abnormality

SCHEMATIC

Slide 21 · Destructive thyroiditis releases preformed hormone

Follicular injury can discharge stored hormone into circulation.

Biochemical thyrotoxicosis occurs without an increase in hormone synthesis.

The textbook distinguishes painful de Quervain from painless lymphocytic thyroiditis.

Follicular injury → release

SCHEMATIC

Slide 22 · Extrathyroidal sources bypass gland hyperfunction

Struma ovarii contains functional thyroid tissue in an ovarian teratoma.

Factitious thyrotoxicosis follows ingestion of exogenous thyroid hormone.

A suppressed pituitary TSH does not locate the hormone source.

Extrathyroidal thyroid hormone

Circulating excess

Thyroid gland TSH suppression

SCHEMATIC

Slide 23 · The symptom complex has two principal drivers

Hypermetabolic effects reflect elevated thyroid hormone signaling.

Enhanced sympathetic / β-adrenergic tone contributes tremor and neurobehavioral changes.

Cardiovascular manifestations often reflect both increased demand and adrenergic effects.

Thyroid hormone excess

↑ Metabolic rate

↑ β-adrenergic effects

SCHEMATIC

Slide 24 · Raised basal metabolic rate produces heat intolerance

Thyroid hormone increases basal metabolic activity.

Peripheral vasodilation and increased cutaneous blood flow facilitate heat loss.

Patients report warmth, sweating, and difficulty tolerating hot environments.

↑ Basal metabolic rate

Peripheral vasodilation

Warmth + sweating

SCHEMATIC

Slide 25 · Weight loss reflects heightened catabolism

Catabolic metabolism increases energy consumption.

Weight loss may occur despite a paradoxically increased appetite.

Unexplained weight decline therefore requires endocrine consideration.

↑ Energy expenditure

Catabolic metabolism

Weight loss despite appetite

SCHEMATIC

Slide 26 · Skin and thermoregulatory findings

Thyrotoxic skin is often soft, warm, and flushed.

Sweating increases along with peripheral heat dissipation.

These findings are consequences of a systemic metabolic state, not a skin-specific disease.

CLINICOPATHOLOGIC LINK

Peripheral perfusion links hormone excess to physical examination findings.

Interpretation

Slide 27 · Cardiovascular adaptation to increased oxygen demand

The hypermetabolic state increases systemic oxygen requirements.

Cardiac contractility and cardiac output often rise to meet demand.

Persistent hemodynamic stress contributes to cardiomegaly and dysfunction.

↑ Peripheral O₂ requirement

↑ Contractility / output

Cardiac workload + risk

SCHEMATIC

Slide 28 · Tachycardia and palpitations

Tachycardia is a common and often early cardiovascular manifestation.

Patients may become aware of forceful or rapid heartbeats.

β-adrenergic overactivity contributes to the symptom burden.

Rapid rhythm (schematic)

Illustrative waveform; Not a clinical ECG

SCHEMATIC

Slide 29 · Atrial fibrillation is an important complication

Arrhythmias, particularly atrial fibrillation, are frequent in older patients.

Palpitations or worsening cardiovascular disease may be the first clue.

The underlying thyrotoxic state should be considered during evaluation.

Irregular rhythm (schematic)

Illustrative waveform; Not a clinical ECG

SCHEMATIC

Slide 30 · Thyrotoxicosis may precipitate heart failure

Existing cardiac disease increases vulnerability to thyroid hormone excess.

Heart failure may emerge in older adults with compromised reserve.

A subset develops potentially reversible thyrotoxic cardiomyopathy.

↑ Peripheral O₂ requirement

↑ Contractility / output

Cardiac workload + risk

SCHEMATIC

Slide 31 · Myocardial changes described in thyrotoxicosis

Focal lymphocytic and eosinophilic infiltrates.

Mild interstitial fibrosis and myofibril fatty changes have been described.

Mitochondria may increase in size and number in affected myocardium.

CLINICOPATHOLOGIC LINK

These are reported tissue changes, not a specific biopsy-based diagnostic signature.

Interpretation

Slide 32 · The nervous system reflects adrenergic activation

Tremor and hyperactivity are common expressions of sympathetic overactivity.

Anxiety, emotional lability, and poor concentration may be prominent.

Insomnia further amplifies neurobehavioral complaints.

Thyroid hormone excess

↑ Metabolic rate

↑ β-adrenergic effects

SCHEMATIC

Slide 33 · Thyroid myopathy is predominantly proximal

Proximal muscle weakness can accompany decreased muscle mass.

Muscle atrophy with fatty infiltration and focal inflammatory changes.

Motor complaints may coexist with other classic thyrotoxic symptoms.

Increased catabolism

Proximal muscle atrophy

Functional weakness

SCHEMATIC

Slide 34 · Gastrointestinal transit is accelerated

Intestinal hypermotility shortens transit time.

Frequent bowel movements or hyperdefecation may result.

Some patients develop fat malabsorption.

↑ Intestinal motility

↓ Transit time

Hyperdefecation

SCHEMATIC

Slide 35 · Lid retraction and stare are adrenergic findings

Sympathetic stimulation of the superior tarsal (Müller) muscle elevates the upper lid.

A wide-eyed stare and lid lag may occur in hyperthyroidism.

These findings alone do not establish Graves orbitopathy.

Upper eyelid retraction

Sympathetic Müller muscle tone

SCHEMATIC

Slide 36 · True infiltrative orbitopathy points toward Graves

Graves-associated orbital disease may cause genuine proptosis / exophthalmos.

Retro-orbital connective tissue and extraocular muscles expand and become edematous.

This process is distinct from adrenergic stare and may persist after hormone control.

Retro-orbital tissue expansion

Graves-specific tissue process

SCHEMATIC

Slide 37 · Excess thyroid hormone reduces skeletal strength

Thyroid hormone stimulates bone resorption.

Cortical bone becomes more porous and trabecular bone volume decreases.

The net result is osteoporosis and increased fracture susceptibility.

Hormone-driven resorption

Cortical + trabecular loss

Osteoporosis / fracture

SCHEMATIC

Slide 38 · Other tissue consequences of hormone excess

Hepatic steatosis may lead to mild hepatomegaly.

Skeletal muscle may show atrophy and fatty infiltration.

Graves disease may be associated with lymphoid hyperplasia and lymphadenopathy.

CLINICOPATHOLOGIC LINK

Systemic organ findings reflect both hormone effects and disease-specific biology.

Interpretation

Slide 39 · Graves-specific manifestations extend beyond thyrotoxicosis

Diffuse thyroid enlargement may be associated with increased blood flow and a bruit.

Infiltrative ophthalmopathy produces true exophthalmos.

Localized pretibial dermopathy occurs in a minority of patients.

Diffuse hyperthyroid gland

Infiltrative orbitopathy

Pretibial dermopathy (minority)

SCHEMATIC

Slide 40 · Apathetic hyperthyroidism can mask the classic picture

Older adults may lack conspicuous tremor, hyperactivity, or heat intolerance.

Weight loss or worsening cardiovascular disease may prompt investigation.

Comorbidity and age blunt the usual clinical phenotype.

Older age + comorbidity

Blunted classic phenotype

Weight loss / cardiac change

SCHEMATIC

Slide 41 · Thyroid storm: Abrupt severe decompensation

Thyroid storm is an acute, severe manifestation of thyrotoxicosis.

In the source, it occurs most commonly in patients with Graves disease.

It is a medical emergency with significant untreated arrhythmic mortality.

Thyroid hormone excess

Stress-triggered crisis

Fever + marked tachycardia

SCHEMATIC

Slide 42 · Common precipitants of thyroid storm

Infection or another acute physiologic stress may precipitate decompensation.

Surgery is a recognized setting.

Stopping antithyroid medication may precipitate an acute episode.

Existing hyperthyroidism

Infection / surgery / withdrawal

Thyroid storm

SCHEMATIC

Slide 43 · Recognizing the storm phenotype

Marked fever may accompany severe thyrotoxicosis.

Tachycardia may be disproportionate to the degree of fever.

Cardiac arrhythmias are a principal life-threatening complication.

Thyroid hormone excess

Stress-triggered crisis

Fever + marked tachycardia

SCHEMATIC

Slide 44 · Start biochemical evaluation with serum TSH

TSH is the most useful single screening test for primary hyperthyroidism.

Negative feedback suppresses TSH early, sometimes before overt hormone elevation.

An isolated TSH value must be interpreted alongside clinical context and free hormones.

↑ Free T3 / T4

Negative pituitary feedback

↓ Serum TSH

SCHEMATIC

Slide 45 · Overt primary hyperthyroidism: The expected pattern

Suppressed serum TSH indicates pituitary feedback inhibition.

Elevated free T4 supports overt thyroid hormone excess.

T3 measurement is useful if the pattern is discordant or T3-predominant.

TSH

Low

Free T4

Elevated

Interpretation

Overt primary hormone excess

The free hormone concentration distinguishes overt disease from earliest subclinical forms.

Slide 46 · Subclinical hyperthyroidism is a biochemical stage

TSH suppression may precede an overt rise in circulating thyroid hormones.

Free T4 can still be within its laboratory reference interval.

An appropriate assessment also accounts for circulating T3.

CLINICOPATHOLOGIC LINK

Use assay-specific reference intervals; No arbitrary numeric cutoff is required here.

Interpretation

Slide 47 · T3-predominant thyrotoxicosis can obscure diagnosis

Some patients have increased circulating T3 without elevated free T4.

Free T4 may even be decreased in the Robbins description.

Direct T3 measurement can resolve suspected discordant biochemical findings.

T3 predominance

Free T4 not elevated

Measure circulating T3

SCHEMATIC

Slide 48 · Non-suppressed TSH changes the differential

Pituitary-associated secondary hyperthyroidism is rare.

TSH may be inappropriately normal or elevated despite excess free hormone.

This differs from expected feedback suppression in primary disease.

Pituitary TSH secretion

Thyroid TSH-receptor activation

High T3/T4 despite non-low TSH

Upstream abnormality

SCHEMATIC

Slide 49 · A stepwise laboratory interpretation pathway

First assess TSH and free thyroid hormone concentrations.

If TSH is suppressed and free T4 is not raised, consider measuring T3.

After confirming biochemical thyrotoxicosis, determine the mechanism and source.

TSH + free T4

T3 if free T4 not elevated

Uptake / antibodies for cause

SCHEMATIC

Slide 50 · Radioiodine uptake evaluates functional activity

Uptake is a mechanistic study of hormone-producing thyroid tissue.

Diffuse, focal, patchy, and low-uptake patterns discriminate key causes.

Pattern interpretation follows confirmation of biochemical hormone excess.

Diffuse

Focal

Patchy

Low

SCHEMATIC

Slide 51 · Diffuse increased uptake favors Graves disease

TSH receptor-stimulating antibodies act throughout the gland.

A radionuclide scan typically shows diffuse increased uptake.

TSI or TRAb can provide complementary etiologic evidence.

Diffuse increased uptake

SCHEMATIC

Slide 52 · Focal increased uptake favors a toxic adenoma

One autonomous nodule produces a focal functional hot spot.

TSH suppression reduces uptake in surrounding follicles.

The resultant distribution differs from Graves-associated diffuse activity.

Focal increased uptake

SCHEMATIC

Slide 53 · Patchy uptake supports toxic multinodular disease

Different nodules exhibit differing functional activity.

Autonomous hot nodules may coexist with less active or cold nodules.

The heterogeneity follows uneven follicular functional autonomy.

Patchy uptake

SCHEMATIC

Slide 54 · Low uptake suggests hormone release or outside supply

Inflammatory follicle damage may release stored hormone without new synthesis.

Extrathyroidal hormone intake does not require cervical thyroid stimulation.

Low thyroid uptake therefore contrasts with synthesis-driven hyperfunction.

Low cervical uptake

SCHEMATIC

Slide 55 · TRAb and TSI support Graves etiology

Thyroid-stimulating immunoglobulins activate the TSH receptor.

TSI and/or TSH-receptor antibody positivity generally supports Graves disease.

Antibody testing is particularly helpful when biochemical thyrotoxicosis has been established.

TSH-receptor antibodies

TSH receptor

CAMP signaling

Hormone synthesis and release

SCHEMATIC

Slide 56 · Clinical and laboratory evidence must converge

Symptoms establish physiologic consequences of hormone excess.

TSH and free hormones support or challenge biochemical thyrotoxicosis.

Uptake distribution and antibodies identify the causative mechanism.

Symptoms and signs

Biochemistry: TSH + hormones

Cause: Uptake / antibodies

SCHEMATIC

Slide 57 · Treatment works at several distinct targets

β-blockers dampen consequences of excess adrenergic tone.

Thionamides reduce new thyroid hormone synthesis.

Iodide, conversion inhibitors, ablation, and surgery act at different steps.

Control β-effects

Reduce new synthesis

Ablate / remove if indicated

SCHEMATIC

Slide 58 · β-blockers relieve adrenergic symptoms

β-blockade improves tachycardia, palpitations, tremulousness, and anxiety.

This strategy targets hormone-driven sympathetic manifestations.

It does not itself remove the underlying source of excess thyroid hormone.

Excess adrenergic tone

β-receptor blockade

Tremor + tachycardia relief

SCHEMATIC

Slide 59 · Thionamides inhibit new hormone synthesis

Methimazole and propylthiouracil inhibit thyroid hormone production.

Their action is mechanistically appropriate for active synthesis-driven causes.

They do not reverse immediate release of hormone already stored in destroyed follicles.

Active synthesis

Methimazole / PTU inhibition

↓ New hormone formation

SCHEMATIC

Slide 60 · High-dose iodide has a temporary suppressive role

In severe thyrotoxicosis, iodide can acutely inhibit hormone release.

Use of iodine solution in severe disease and thyroid storm.

This is a temporary intervention rather than a stand-alone definitive cure.

Severe hyperthyroidism

High-dose iodide (temporary)

↓ Hormone release

SCHEMATIC

Slide 61 · Peripheral T4-to-T3 conversion is another target

T4 is converted to biologically potent T3 in peripheral tissues.

Propylthiouracil inhibits this conversion in addition to inhibiting synthesis.

The textbook also notes other agents capable of reducing peripheral conversion.

Peripheral T4

Deiodination

Active T3

SCHEMATIC

Slide 62 · Definitive therapy removes functional thyroid tissue

Radioactive iodine is taken up by thyroid tissue and ablates gland function.

Thyroidectomy surgically removes hormone-producing tissue.

Choice of definitive therapy depends on the underlying disease and clinical setting.

Functional thyroid tissue

Radioiodine or surgery

Reduced gland capacity

SCHEMATIC

Slide 63 · Pituitary-driven disease requires a different strategy

TSH-secreting pituitary tumors are not autonomous thyroid disorders.

Pituitary surgery, somatostatin analogs, or irradiation among options.

Therapeutic logic must address the inappropriate upstream TSH stimulus.

Pituitary TSH secretion

Thyroid TSH-receptor activation

High T3/T4 despite non-low TSH

Upstream abnormality

SCHEMATIC

Slide 64 · Case: Diffuse thyrotoxicosis with a thyroid bruit

CLINICAL REASONING

Illustrative case: Weight loss, tremor, diffuse enlarged thyroid, and suppressed TSH.

Elevated free T4 and diffusely increased uptake support active glandular synthesis.

A thyroid bruit and positive TSI would further favor Graves disease.

Which evidence localizes the cause?

Diffuse uptake and receptor antibodies favor Graves-mediated hyperfunction.

Illustrative teaching case

Slide 65 · Case: Painful thyroid illness with hormone excess

CLINICAL REASONING

Illustrative case: Neck pain, transient thyrotoxic symptoms, and suppressed TSH.

Low uptake supports destructive release rather than increased synthesis.

The underlying thyroiditis mechanism is central to treatment selection.

Why is the uptake low despite high thyroid hormone?

Stored hormone enters blood while new hormone synthesis is not increased.

Illustrative teaching case

Slide 66 · Case: One active nodule

CLINICAL REASONING

Illustrative case: Low TSH, excess hormone, and a dominant focal uptake region.

A solitary hot nodule suggests toxic adenoma physiology.

Surrounding relatively suppressed thyroid activity reinforces focal autonomy.

How does pituitary feedback shape the scan?

TSH suppression quiets surrounding nonautonomous thyroid tissue.

Illustrative teaching case

Slide 67 · Case: New atrial fibrillation in an older adult

CLINICAL REASONING

Illustrative case: Weight loss, new atrial fibrillation, and few obvious adrenergic signs.

Apathetic hyperthyroidism remains plausible despite muted classic symptoms.

Serum TSH followed by free hormone assessment provides the biochemical pathway.

What is the key diagnostic pitfall?

Older patients may exhibit predominantly cardiovascular manifestations.

Illustrative teaching case

Slide 68 · Case: Severe febrile tachycardia after a stressor

CLINICAL REASONING

Illustrative case: Known Graves disease, infection, fever, and marked tachycardia.

Thyroid storm should be recognized as an urgent clinical syndrome.

Arrhythmias can be fatal without emergency management.

What makes the presentation emergent?

Sudden decompensation with disproportionate tachycardia and systemic instability.

Illustrative teaching case

Slide 69 · Integrating patterns at the bedside

Graves: Diffuse production; Typically diffuse uptake; TRAb / TSI can be positive.

Toxic adenoma: Focal production and a solitary increased-uptake nodule.

Thyroiditis / extrathyroidal supply: Hormone excess despite low cervical uptake.

Pattern

Mechanism

Uptake

Graves

Diffuse stimulation

Diffuse high

Toxic adenoma

Focal autonomy

Focal high

Thyroiditis

Release of stores

Low

Biochemical similarity does not imply etiologic equivalence.

Slide 70 · Five diagnostic errors to avoid

Do not equate thyrotoxicosis with increased glandular synthesis.

Do not mistake lid lag or stare for Graves-specific infiltrative orbitopathy.

Do not exclude T3 thyrotoxicosis solely because free T4 is not elevated.

Do not overlook biochemical hyperthyroidism in an older patient with arrhythmia.

CLINICOPATHOLOGIC LINK

A fifth error: Interpreting uptake or antibodies before establishing the hormonal state.

Interpretation

Slide 71 · Synthesis: From hormones to mechanism

Clinical excess arises from hypermetabolism plus increased adrenergic tone.

TSH and free hormone tests establish the biochemical pattern.

Uptake and receptor antibodies help distinguish major etiologies.

Therapeutic targets differ for synthesis, release, and extrathyroidal supply.

Slide 72 · Source

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th edition (2026).

Primary section: Hyperthyroidism; contextual sections: Thyroid Gland, Graves Disease, and Multinodular Goiter.

All process diagrams and gland drawings in this lecture are original schematics, not clinical or histologic specimens.