Toxic multinodular goitre and toxic adenoma

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Autonomy develops when thyroid tissue produces hormone without normal TSH control. In multinodular disease, multiple clones create heterogeneous function; in an adenoma, a single clone dominates. Longstanding iodine deficiency and increasing age contribute epidemiologically, while an iodine load can uncover previously compensated autonomy. Unlike Graves disease, there is no autoimmune remission target and eye disease is not a characteristic feature.

Clinical priority often lies outside the neck. Persistent even mild hormone excess increases risk of atrial fibrillation, heart failure and bone loss, especially in older adults. A patient can appear relatively calm yet have substantial cardiac morbidity. Evaluate pulse rhythm, exercise tolerance, falls or fracture risk, weight change and cognition alongside the thyroid profile.

Functional and structural assessments answer different questions. Scintigraphy maps autonomy; ultrasound characterises nodules and cervical nodes when a palpable or imaging-detected lesion requires risk stratification. A low TSH should be communicated on the ultrasound request. Compression, retrosternal extension or suspicious lymphadenopathy can make surgery appropriate even when radioiodine would otherwise control hormone excess.

Key points

Toxic multinodular goitre contains several autonomously functioning areas, whereas toxic adenoma is a single dominant autonomous nodule suppressing the surrounding gland.
Both become more common with age and often present gradually through atrial fibrillation, heart failure, weight loss or osteoporosis rather than classic Graves features.
Biochemistry shows suppressed TSH with raised free T4 and/or free T3; T3-predominant disease is particularly common in nodular autonomy.
An irregular multinodular gland suggests toxic multinodular goitre, while a solitary nodule suggests adenoma, but palpation alone cannot establish function or cancer risk.
TRAb is usually negative and scintigraphy demonstrates patchy multiple uptake or one focal hot nodule with suppression of background tissue.
NICE generally favours radioiodine as first-line definitive treatment for toxic multinodular goitre when suitable; surgery is preferred for compression, suspected malignancy or unsuitable radioiodine.
For a toxic adenoma, radioiodine or hemithyroidectomy can be definitive, selected by nodule anatomy, patient priorities, surgical risk and local expertise.
Antithyroid medicine controls hormone synthesis but autonomy rarely enters durable remission, so it is usually a bridge or lifelong treatment only when definitive options are unsuitable.
A confirmed hyperfunctioning hot nodule is rarely malignant and is not routinely aspirated unless ultrasound or clinical features create a separate concern.
Pregnancy and breastfeeding exclude radioiodine and need a specialist plan; iodine contrast can aggravate autonomy and affect later radionuclide treatment timing.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Multifocal nodular autonomy

Several thyroid cell clones produce hormone independently of TSH, often after longstanding multinodular gland change and increasing age.

Single autonomous adenoma

One dominant nodule develops TSH-independent hormone production, suppressing TSH and reducing activity in the surrounding non-autonomous thyroid tissue.

Iodine-related unmasking

An iodine load can provide substrate to previously compensated autonomous tissue and reveal clinically important thyrotoxicosis.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Thyroid clones become autonomous
Nodular tissue produces T4 and T3 without normal dependence on pituitary TSH stimulation as the process continues.
2
TSH and normal tissue are suppressed
Rising hormone reduces pituitary TSH, lowering activity in non-autonomous thyroid while the toxic focus continues secretion.
3
Persistent thyrotoxicosis develops
Unlike Graves disease, nodular autonomy has no autoimmune remission process and often continues unless the functioning tissue is controlled.
4
Structural effects may coexist
The same gland can enlarge, extend retrosternally or contain sonographically concerning nodules independently of its hormone production.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Multinodular autonomy

An older patient has an irregular enlarged gland, gradual biochemical progression and no orbitopathy. Scintigraphy shows heterogeneous patchy uptake with suppressed intervening tissue.

Single toxic adenoma

A discrete nodule accompanies suppressed TSH and focal intense uptake with suppression of the remaining gland; free T3 may rise before free T4.

Cardiac-dominant presentationRed flag

New atrial fibrillation, worsening angina, exertional dyspnoea, ankle swelling or high-output failure may be the main manifestation and deserves urgent cardiovascular assessment according to stability.

Compressive goitreRed flag

Dysphagia, voice change, cough, positional dyspnoea, stridor, facial congestion or distended neck veins suggests oesophageal, recurrent-laryngeal, tracheal or mediastinal compression and strengthens the surgical pathway.

Malignancy concern

Rapid growth, hard fixation, cervical nodes, persistent hoarseness or suspicious ultrasound features need cancer-pathway assessment; functional autonomy does not license dismissal of a separate suspicious lesion.

Iodine-triggered worsening

Abrupt hormone rise after iodinated contrast, amiodarone or high iodine exposure suggests Jod-Basedow physiology in autonomous tissue and requires endocrine review, particularly with cardiac symptoms.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
TSH, free T4 and free T3First step
Why
Confirm overt or subclinical hormone excess and identify T3 predominance.
Interpretation and limitations
TSH is suppressed; one or both free hormones may be raised. Normal free T4 with high free T3 is overt T3 toxicosis, not subclinical disease.
02
TSH-receptor antibodies
Why
Separate autoimmune Graves disease from nodular autonomy when phenotype is uncertain.
Interpretation and limitations
A negative result supports but does not prove autonomy; a clearly positive result shifts the diagnosis towards Graves or mixed pathology and can alter imaging needs.
03
Technetium thyroid scintigraphy
Why
Map the number and distribution of functioning autonomous areas.
Interpretation and limitations
Patchy uptake supports toxic multinodular goitre; a solitary hot focus with background suppression supports toxic adenoma. Low uptake prompts thyroiditis, exogenous hormone or iodine exposure.
04
Structured thyroid and nodal ultrasound
Why
Characterise palpable nodules, goitre anatomy and any cancer-risk features.
Interpretation and limitations
Report a local risk category, dimensions and cervical nodes. Functional hot nodules usually avoid FNA unless a distinct sonographic or clinical concern remains.
05
ECG, echocardiography and cardiac biomarkers as indicated
Why
Identify arrhythmia, heart failure or ischaemic consequences of prolonged excess.
Interpretation and limitations
Atrial fibrillation requires independent haemodynamic, stroke-risk and anticoagulation assessment; correcting thyroid hormone does not erase immediate embolic risk.
06
CT neck and chest without avoidable iodine when feasible
Why
Define retrosternal extension and airway or mediastinal compression before surgery.
Interpretation and limitations
Tracheal narrowing, deviation or mediastinal extension supports specialist surgical planning. Discuss contrast necessity because iodine can worsen hyperthyroidism and delay radioiodine.
07
Baseline full blood count and liver function
Why
Prepare safely when carbimazole is used before definitive treatment.
Interpretation and limitations
Clinically important neutropenia or hepatic dysfunction needs specialist discussion; later urgent testing is symptom-triggered for infection or liver injury.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Graves disease

Diffuse uptake, receptor antibodies and thyroid eye disease support autoimmune stimulation rather than focal or patchy nodular autonomy.

Destructive thyroiditis

Low uptake, gland pain or a self-limited release pattern indicates follicular leakage rather than continuing autonomous synthesis.

Exogenous thyroid hormone

External hormone suppresses both TSH and gland uptake, with medicine history separating it from an active toxic nodule.

Non-functioning thyroid nodule

A structural nodule with normal TSH and no focal uptake may need ultrasound risk assessment but does not explain thyrotoxicosis.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Confirm autonomyJoin biochemical and functional evidenceFirst stepSuppressed TSH occurs with a palpable nodule or multinodular gland.

1Measure free T4 and free T3, examine the neck and nodes, and review Graves signs, iodine exposure, amiodarone and pregnancy possibility.
2Use TRAb and endocrinology-directed scintigraphy to establish autonomy; obtain ultrasound for structural characterisation when the nodule or goitre meets a clinical indication.
3DefinitiveAssess cardiac rhythm, heart failure, bone and compression risk before deciding how quickly hormone control and definitive treatment are needed.

02Multinodular definitive careChoose radioiodine or thyroidectomyDefinitiveToxic multinodular goitre is confirmed and acute control is underway.

1DefinitiveOffer radioiodine as the usual first definitive option when suitable, explaining delayed effect, radiation precautions and likely need for lifelong thyroid surveillance.
2Prefer surgical review for compression, substantial retrosternal extension, malignancy suspicion, very large goitre or when radioiodine is inappropriate or declined.
3DefinitiveIf neither definitive route is suitable, agree long-term antithyroid treatment with endocrine monitoring and explicit agranulocytosis, hepatic and reproductive safety advice.

03Adenoma definitive careTreat a solitary autonomous noduleDefinitiveScintigraphy confirms one toxic adenoma with appropriate structural assessment.

1Discuss radioiodine and hemithyroidectomy, including speed, hypothyroidism likelihood, radiation constraints, operative risks and the value of a tissue diagnosis when concern exists.
2Control significant hormone excess before intervention with specialist-selected carbimazole and symptom therapy, avoiding delay when compression or malignancy requires urgency.
3After treatment, monitor thyroid function for delayed hypothyroidism or persistent autonomy and reassess any nodule not explained by the treated hot focus.

04Cardiac complicationTreat consequences in parallelAtrial fibrillation, heart failure or angina accompanies nodular thyrotoxicosis.

1Assess stability and use emergency cardioversion or acute heart-failure pathways when indicated; thyroid treatment is not a substitute for immediate cardiovascular care.
2Select rate control with attention to low-output failure, asthma and conduction disease, and assess anticoagulation using the current atrial-fibrillation guideline.
3DefinitiveExpedite definitive thyroid control because persistent autonomous hormone production promotes recurrence even when the first cardiac episode settles.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Controls new hormone production before radioiodine or surgery, or long term if definitive care is unsuitable.

Carbimazole for autonomous hyperthyroidism

Choose a BNF-listed initial total commonly within 15 to 40 mg daily according to free-hormone elevation, then titrate through endocrinology while definitive treatment is planned.

Check baseline blood count and liver tests. Stop for fever, sore throat or mouth ulcers pending urgent count; address pregnancy, contraception, hepatic symptoms and pancreatitis under current MHRA advice.

Reduces tremor and adrenergic cardiac symptoms while hormone synthesis comes under control.

Beta blocker for nodular thyrotoxic symptoms

Use an individual BNF-checked oral beta-blocker regimen, for example propranolol 10 to 40 mg three or four times daily when appropriate, titrated to pulse and tolerance.

Check for asthma, bradycardia, heart block, hypotension and low-output failure. Rate control does not replace anticoagulation assessment or treatment of decompensated heart failure.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Atrial fibrillation

Persistent even mild hormone excess increases atrial arrhythmia and embolic stroke risk, especially in older adults.

Heart failure

Sustained tachycardia and increased cardiac workload can decompensate underlying structural or ischaemic disease, causing pulmonary oedema or low-output failure.

Bone loss and fracture

Persistent nodular thyrotoxicosis accelerates skeletal turnover, reducing bone density and increasing osteoporosis and fragility-fracture risk over time.

Compressive goitre

Large or retrosternal nodular growth can cause dyspnoea, dysphagia, positional symptoms or recurrent laryngeal nerve dysfunction.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Follow free T4 and free T3 during carbimazole titration, recognising that TSH recovery lags and early dose changes should not chase suppression alone.
Monitor pulse and rhythm, heart-failure symptoms, weight and exercise tolerance; arrange ECG review promptly when palpitations or syncope develops.
After radioiodine, use the local scheduled thyroid-test pathway to detect both persistent hyperthyroidism and delayed permanent hypothyroidism.
After hemithyroidectomy, review histology, calcium only as clinically relevant, wound and voice symptoms, and thyroid function of the remaining lobe.
For long-term carbimazole, repeat safety bloods when symptoms indicate rather than by automatic schedule, while maintaining clear infection and liver safety-netting.
Reassess goitre size, compression and nodal features when the neck changes; biochemical control does not guarantee structural stability.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Autonomy rarely remits

Unlike Graves autoimmunity, autonomous clones persist when carbimazole stops, which is why durable radioiodine or surgical planning usually remains necessary.

Hot usually means low malignancy

A truly autonomous nodule on scintigraphy is rarely cancerous, but suspicious nodes or a separate cold lesion still need structural risk assessment.

T3 can lead

Autonomous nodules may preferentially produce T3, so suppressed TSH plus normal free T4 needs free T3 before being labelled subclinical.

Iodine can unmask autonomy

Contrast or medicine-derived iodine provides substrate to tissue no longer controlled by TSH and can precipitate a clinically important hormone surge.

Cardiac control is separate

Restoring euthyroidism may aid rhythm, but stroke prevention, heart-failure therapy and unstable arrhythmia management follow their own evidence-based pathways from presentation.

11Common pitfallsFrequent interpretation and management errors.

01
Expecting a finite carbimazole course to induce remission of autonomous nodules.
02
Calling disease subclinical after checking free T4 but not free T3.
03
Sending every hot nodule for aspiration despite no separate suspicious feature.
04
Ignoring positional breathlessness or voice change because biochemistry is improving.
05
Using radioiodine without excluding pregnancy or planning breastfeeding restrictions.
06
Assuming thyroid control alone resolves atrial-fibrillation stroke risk.
07
Ordering iodinated imaging without considering hormone worsening and radioiodine timing.