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Hyperthyroid

Thyroid management

Last updated 22 Mar 2026 · Thyroid Disorders

Introduction

Hyperthyroidism is a clinical syndrome resulting from excessive thyroid hormone production and/or release. It affects approximately 1-2% of Australians, with a higher prevalence in women (5-10:1 female to male ratio) and peak incidence between 20-50 years of age. The condition presents significant morbidity if untreated and requires prompt recognition and appropriate management.

ℹ️
Clinical Definition: Biochemical hyperthyroidism is defined as suppressed TSH (<0.1 mIU/L) with elevated free T4 and/or free T3. Clinical hyperthyroidism includes both biochemical abnormalities and symptomatic disease.

Common Causes in Australia

Cause Frequency Key Features
Graves' disease 70-80% Diffuse goitre, ophthalmopathy, TSI positive
Toxic multinodular goitre 15-20% Elderly patients, nodular goitre, normal eyes
Toxic adenoma 3-5% Single hot nodule, suppressed surrounding tissue
Thyroiditis 2-5% Transient, painful (subacute) or painless (postpartum)
Iodine-induced 1-2% Medication history, contrast exposure

Clinical Spectrum

Subclinical
Subclinical Hyperthyroidism
Suppressed TSH with normal T4/T3. May be asymptomatic or have subtle symptoms. Risk of progression and cardiac effects in elderly.
Outpatient management
Overt
Overt Hyperthyroidism
Suppressed TSH with elevated T4/T3. Classic symptoms present. Requires definitive treatment to prevent complications.
Outpatient ± urgent referral
Crisis
Thyroid Storm
Life-threatening emergency. Hyperthermia, altered consciousness, cardiovascular instability. Mortality 10-30% if untreated.
Emergency admission
⚠️
High-Risk Populations: Elderly patients may present with apathetic hyperthyroidism (minimal symptoms but increased cardiac risk). Pregnant women require urgent endocrinology referral due to maternal and fetal complications.

Guideline Scope

This guideline covers the diagnosis, investigation, and management of hyperthyroidism in Australian healthcare settings, with specific considerations for:

  • Primary care assessment and initial management
  • Emergency presentation and thyroid storm
  • Special populations (pregnancy, elderly, children)
  • Aboriginal and Torres Strait Islander health considerations
  • Referral pathways and follow-up protocols
✅
Treatment Goals: Restore euthyroid state, prevent complications, address underlying cause, and optimise quality of life with consideration of patient preferences and comorbidities.

Clinical Presentation

Mild
Subclinical Hyperthyroidism
TSH suppressed, normal T3/T4. Often asymptomatic or subtle symptoms.
Outpatient management
Moderate
Overt Hyperthyroidism
Classic symptoms present. TSH suppressed, elevated T3/T4. Functional impairment.
Outpatient management
Severe
Thyroid Storm
Life-threatening. Hyperpyrexia, altered mental state, cardiovascular instability.
Emergency admission required

Cardinal Symptoms

Sympathetic Symptoms
  • Palpitations, tachycardia
  • Tremor (fine, distal)
  • Anxiety, restlessness
  • Heat intolerance
  • Excessive sweating
  • Hyperdefecation
Metabolic Symptoms
  • Weight loss with increased appetite
  • Fatigue, weakness
  • Muscle weakness (proximal)
  • Insomnia
  • Menstrual irregularity
  • Hair loss

Physical Examination Findings

System Clinical Signs Specific Features
Cardiovascular Tachycardia, systolic hypertension, atrial fibrillation Wide pulse pressure, systolic flow murmur
Thyroid gland Goitre, bruit, tenderness Graves': diffuse enlargement, bruit. Toxic nodule: palpable nodule
Neurological Fine tremor, hyperreflexia, proximal weakness Periodic paralysis (especially Asian males)
Skin/Hair Warm, moist skin, hair thinning Graves': pretibial myxoedema (rare)
Eyes Lid retraction, stare Graves' ophthalmopathy: proptosis, diplopia, periorbital oedema
🚨
Thyroid Storm Features: Hyperpyrexia (>38.5°C), altered mental state, cardiovascular instability (heart failure, arrhythmias), gastrointestinal symptoms (nausea, vomiting, diarrhoea), precipitated by infection, surgery, or medication non-compliance.

Cause-Specific Presentations

1
Graves' Disease (80%)
Diffuse goitre, eye signs, pretibial myxoedema. Often young women. Family history of autoimmune disease.
2
Toxic Multinodular Goitre
Older patients, irregular goitre, no eye signs. Gradual onset. May present with isolated atrial fibrillation.
3
Toxic Adenoma
Single palpable nodule, younger patients. No goitre or eye signs.
4
Thyroiditis
Painful thyroid (subacute), recent pregnancy (postpartum), or drug-induced. Transient hyperthyroidism.
⚠️
Apathetic Hyperthyroidism in Elderly: May present with weight loss, depression, atrial fibrillation, and heart failure rather than classic hyperadrenergic symptoms. High index of suspicion required.

Red Flag Symptoms

  • Sudden onset severe symptoms
  • Fever with altered mental state
  • Cardiovascular compromise
  • Severe eye symptoms (visual disturbance, severe pain)
  • Compressive symptoms (stridor, dysphagia)
  • Periodic paralysis
ℹ️
Clinical Pearl: Hyperthyroidism can unmask or worsen underlying conditions including coronary artery disease, heart failure, and osteoporosis. Consider cardiac assessment in older patients or those with risk factors.

Investigations

ℹ️
Key Principle: TSH is the most sensitive screening test. If TSH is suppressed, measure free T4 and free T3 to confirm hyperthyroidism and assess severity.

Initial Laboratory Investigations

  • Essential
    Thyroid Stimulating Hormone (TSH)
    Most sensitive initial test. TSH <0.1 mIU/L suggests hyperthyroidism. Normal TSH excludes primary hyperthyroidism.
  • Essential
    Free Thyroxine (fT4)
    If TSH suppressed. Normal range 9-24 pmol/L. Elevated confirms hyperthyroidism.
  • Essential
    Free Triiodothyronine (fT3)
    If TSH suppressed. Normal range 3.5-6.5 pmol/L. May be elevated when fT4 normal (T3 toxicosis).
  • First Line
    Full Blood Count
    Check for anaemia, neutropenia. Baseline before antithyroid drugs.
  • First Line
    Liver Function Tests
    Baseline ALT, bilirubin. Hyperthyroidism can cause elevated enzymes. Monitor during treatment.
  • First Line
    Electrolytes, Urea, Creatinine
    Check for hypokalaemia, assess renal function before radioiodine therapy.

Aetiology-Specific Investigations

  • Second Line
    TSH Receptor Antibodies (TRAb)
    Confirms Graves' disease. Positive in >95% of Graves' patients. Useful for predicting remission and guiding treatment duration.
  • Second Line
    Thyroid Peroxidase Antibodies (TPOAb)
    May be positive in Graves' disease or Hashimoto's thyroiditis. Less specific than TRAb for Graves'.
  • Specialist
    Technetium-99m Thyroid Scan
    Differentiates Graves' (diffuse uptake) from toxic nodular disease (patchy uptake) or thyroiditis (low uptake).
  • Specialist
    Radioiodine Uptake Study
    24-hour uptake. High in Graves'/toxic nodules, low in thyroiditis. Required before radioiodine treatment planning.
  • Available
    Thyroid Ultrasound
    Assess gland size, nodules, blood flow. Doppler shows increased vascularity in Graves' disease.
⚠️
Thyroid Storm Investigation: If suspected, add arterial blood gas, blood glucose, cortisol, cardiac enzymes, and ECG. Consider blood cultures if febrile.

Interpretation Patterns

Pattern TSH fT4 fT3 Clinical Significance
Overt Hyperthyroidism ↓↓ (<0.1) ↑ ↑ Classical hyperthyroidism requiring treatment
T3 Toxicosis ↓↓ (<0.1) Normal ↑ Early or mild hyperthyroidism, toxic nodules
Subclinical ↓ (0.1-0.4) Normal Normal Mild disease, monitor or treat if symptomatic
Central Hyperthyroidism ↑ or Normal ↑ ↑ TSH-secreting adenoma (rare)

Monitoring During Treatment

Baseline
TSH, fT4, fT3, FBC, LFTs, U&E
2-4 weeks
TSH, fT4, fT3 (earlier if severe). FBC if on antithyroid drugs
6-8 weeks
TSH, fT4, fT3. FBC, LFTs if on antithyroid drugs
3-6 monthly
TSH, fT4 when stable. TRAb annually in Graves' to assess remission likelihood
🚨
Drug Monitoring Alert: Check FBC and LFTs within 2 weeks of starting carbimazole or propylthiouracil. Stop drug immediately if neutrophil count <1.0 × 10⁹/L or ALT >3× upper limit normal.

Special Populations — Investigation Adjustments

🤰 Pregnancy
TRAb Check if Graves' disease — high levels predict neonatal hyperthyroidism
TFTs Monitor monthly during pregnancy — thyroid function changes rapidly
TSH range Use pregnancy-specific TSH ranges (lower in first trimester)
👴 Elderly
ECG Add ECG and cardiac enzymes — higher risk of atrial fibrillation
Echocardiogram Consider if heart failure suspected
DEXA scan Bone density scan if prolonged subclinical hyperthyroidism

Treatment

⚠️
Thyrotoxic Crisis: Medical emergency requiring immediate IV beta-blockers, high-dose antithyroid drugs, corticosteroids and supportive care. Consider plasmapheresis if severe.

Treatment Approach by Cause

Graves' Disease
First-line: Antithyroid drugs
Carbimazole preferred. Consider radioiodine or surgery for refractory cases.
Outpatient management
Toxic Nodular Goitre
Radioiodine therapy
First-line treatment. Surgery if contraindicated to radioiodine.
Specialist referral
Thyrotoxic Crisis
Emergency management
High-dose antithyroid drugs + beta-blockers + corticosteroids.
Hospital admission

Antithyroid Medications

💊
Carbimazole
Neo-Mercazole® · First-line antithyroid
Adult Dose Initial: 15-40 mg daily, maintenance: 5-15 mg daily
Paediatric 0.5-1 mg/kg/day divided doses
Route Oral, once daily or divided doses
Duration 12-18 months minimum
PBS Status ✔ PBS General Benefit
💊
Propylthiouracil (PTU)
PTU · Second-line antithyroid
Adult Dose Initial: 300-600 mg daily, maintenance: 50-150 mg daily
Route Oral, divided 6-8 hourly
Indications First trimester pregnancy, carbimazole intolerance
PBS Status ✔ PBS General Benefit
🚨
Agranulocytosis Risk: Occurs in 0.3% of patients on antithyroid drugs. Advise patients to stop medication and seek urgent medical attention if sore throat, fever, mouth ulcers or other signs of infection develop.

Symptomatic Management

🫀
Propranolol
Inderal® · Beta-blocker for symptom control
Adult Dose 40-160 mg daily divided doses
Route Oral, 2-3 times daily
Contraindications Asthma, COPD, heart block, severe heart failure
PBS Status ✔ PBS General Benefit
🫀
Atenolol
Tenormin® · Alternative beta-blocker
Adult Dose 25-100 mg daily
Route Oral, once daily
Renal Adj. Reduce dose if CrCl <35 mL/min
PBS Status ✔ PBS General Benefit

Definitive Treatment Options

Treatment Indications Contraindications Success Rate
Radioiodine (I-131) Graves' disease, toxic nodular goitre, age >18 years Pregnancy, breastfeeding, ophthalmopathy 80-90%
Total thyroidectomy Large goitre, suspected malignancy, pregnancy planning High surgical risk, severe comorbidities 95-99%
Antithyroid drugs Graves' disease, pregnancy, young patients Previous agranulocytosis, severe hepatotoxicity 50-60%

Treatment Monitoring

1
Baseline Assessment
FBC, LFTs, TFTs before starting antithyroid drugs
2
Initial Monitoring
TFTs at 4-6 weeks, then 3-monthly once stable
3
Safety Monitoring
FBC if infection symptoms. LFTs if clinically indicated
4
Treatment Duration
Minimum 12-18 months for Graves' disease
🤱 Pregnancy
Propylthiouracil (PTU) Preferred in first trimester. Switch to carbimazole in second trimester if possible
Beta-blockers Propranolol safe in pregnancy. Avoid atenolol (growth restriction)
Radioiodine Absolutely contraindicated in pregnancy and breastfeeding
👶 Paediatrics
Carbimazole 0.5-1 mg/kg/day. Monitor growth and development
Propranolol 1-2 mg/kg/day divided doses for symptom control
Radioiodine Generally avoided in children <18 years
👴 Elderly
Beta-blockers Start low dose. Monitor for heart failure, bradycardia
Radioiodine Often preferred definitive treatment in elderly
Surgery Higher perioperative risk. Careful anaesthetic assessment
🫘 Renal Impairment
Carbimazole No dose adjustment required for renal impairment
Atenolol Reduce dose if CrCl <35 mL/min. Consider propranolol alternative
Radioiodine Use with caution in severe renal impairment — consult nuclear medicine

Special Populations

🤰 Pregnancy & Breastfeeding
Key risks Thyrotoxicosis increases risk of pre-eclampsia, preterm labour, IUGR. TSI can cross placenta causing fetal/neonatal thyrotoxicosis.
TFT monitoring Monitor TSH, free T4 monthly during pregnancy
Preferred treatment Propylthiouracil (1st trimester), then carbimazole from 2nd trimester onwards
👶 Paediatric Populations
Remission Higher remission rates with antithyroid drugs vs adults
Carbimazole 0.5-1 mg/kg/day divided 8-12 hourly. Monitor growth and development.
Propylthiouracil 5-10 mg/kg/day divided 8 hourly. Second-line in paediatrics.
👴 Elderly Patients
AF risk Increased risk of atrial fibrillation and heart failure. May present with apathetic thyrotoxicosis.
Beta-blockers Start low dose, monitor for heart block
Warfarin Enhanced anticoagulation effect — monitor INR closely
🫘 Renal Impairment
Carbimazole No dose adjustment required
Propylthiouracil No dose adjustment required. Monitor for accumulation in severe impairment.
Iodinated contrast Avoid if possible — may precipitate thyroid storm
🫀 Hepatic Impairment
LFT monitoring Baseline LFTs before starting antithyroid drugs. Monitor weekly for first month, then monthly.
Propylthiouracil Higher hepatotoxicity risk — avoid if possible
Carbimazole Preferred agent in hepatic impairment. Discontinue if ALT >3× ULN.
🛡️ Immunocompromised
Agranulocytosis Higher risk of antithyroid drug-induced agranulocytosis. Weekly FBC for first month, then fortnightly for 3 months.
Warning signs Fever, sore throat, mouth ulcers — stop medication immediately and seek urgent review
🚨
Pregnancy Alert: Radioactive iodine is absolutely contraindicated in pregnancy and breastfeeding. Perform pregnancy test before RAI in all women of childbearing age.
💊
Propylthiouracil
PTU · First-line in pregnancy (1st trimester)
Pregnancy Dose 50-150 mg 8 hourly oral
Paediatric 5-10 mg/kg/day divided 8 hourly
Breastfeeding Compatible — minimal transfer to breast milk
PBS Status ✔ PBS General Benefit
💊
Carbimazole
Neo-Mercazole® · Preferred post 1st trimester
Pregnancy Dose 5-20 mg daily oral (2nd/3rd trimester)
Paediatric 0.5-1 mg/kg/day divided 8-12 hourly
Elderly Start 5 mg daily, titrate slowly
PBS Status ✔ PBS General Benefit
Aboriginal and Torres Strait Islander Health
Access to Specialist Care
Remote communities may have limited endocrinologist access. Utilise telehealth consultations and strengthen primary care management protocols.
Medication Compliance
Cultural preferences for traditional healing may impact adherence. Engage Aboriginal Health Workers and respect cultural practices while ensuring medical safety.
Monitoring Challenges
Regular blood tests may be difficult in remote areas. Coordinate with visiting medical services and use point-of-care testing where available.
Comorbidity Considerations
Higher rates of diabetes and cardiovascular disease. Monitor for drug interactions and coordinate care with existing chronic disease management programs.
ℹ️
Cultural Safety: Some Aboriginal and Torres Strait Islander people may have concerns about radioactive treatments. Provide culturally appropriate education and involve family/community support where appropriate.

Follow-Up & Prevention

📅
Key Monitoring Principle: TSH may remain suppressed for months after achieving clinical euthyroidism. Free T4 and T3 are better early indicators of treatment response.

Follow-Up Schedule

2-4 weeks

Initial Response Check

  • Clinical assessment (heart rate, tremor, weight)
  • TFTs (TSH, free T4, free T3)
  • FBC if on antithyroid drugs
  • Adjust medication dose if needed
6-8 weeks

Treatment Adjustment

  • TFTs to guide dose titration
  • FBC for drug monitoring
  • Consider block-and-replace if on carbimazole
3-6 months

Stabilisation Period

  • Monthly TFTs until stable
  • Consider remission in Graves' disease after 12-18 months
  • Ophthalmology review if eye symptoms
Long-term

Ongoing Management

  • 3-6 monthly TFTs once stable
  • Annual review if in remission
  • Monitor for hypothyroidism post-treatment

Monitoring Parameters

  • Essential
    Thyroid Function Tests
    TSH, free T4, free T3 — frequency as per timeline above
  • Essential
    Full Blood Count
    Monthly while on antithyroid drugs — monitor for agranulocytosis
  • Available
    Liver Function Tests
    Baseline and if clinically indicated — carbimazole hepatotoxicity risk
  • Specialist
    TSH Receptor Antibodies
    Monitor in pregnancy; assess remission likelihood in Graves' disease
  • Referral
    Thyroid Uptake Scan
    Post-partum thyroiditis vs Graves' disease differentiation

Treatment Completion & Remission

1
Assess for Remission
After 12-18 months of antithyroid therapy in Graves' disease, consider gradual withdrawal if TRAb negative and clinically stable
2
Gradual Withdrawal
Reduce carbimazole by 50% every 4-6 weeks while monitoring TFTs closely
3
Post-Treatment Monitoring
TFTs at 6 weeks, 3 months, 6 months, then annually — 50% relapse risk in first year
⚠️
Relapse Risk: Graves' disease relapses in 50-60% of patients within 2 years of stopping antithyroid drugs. Higher risk with: male gender, younger age, large goitre, high TRAb levels.

Long-Term Complications

Complication Monitoring Management
Thyroid Eye Disease Visual symptoms, diplopia, eye pain Ophthalmology referral, selenium supplementation, smoking cessation
Atrial Fibrillation ECG, symptoms of palpitations Anticoagulation as per CHA₂DS₂-VASc, rate/rhythm control
Osteoporosis DEXA scan if prolonged hyperthyroidism Calcium/vitamin D supplementation, bisphosphonates if indicated
Post-treatment Hypothyroidism Regular TFTs post-RAI or surgery Levothyroxine replacement therapy

Prevention Strategies

Primary Prevention
  • Adequate iodine intake (but avoid excess)
  • Smoking cessation (reduces Graves' disease risk)
  • Stress management
  • Avoid high-dose iodine supplements
Secondary Prevention
  • Regular monitoring during high-risk periods
  • Pregnancy planning and monitoring
  • Medication adherence education
  • Early recognition of relapse symptoms

Patient Education & Self-Monitoring

💡
Patient Education Points: Teach patients to recognise symptoms of both hyperthyroidism relapse and hypothyroidism, emphasise medication compliance, and provide written information about when to seek urgent medical care.
Symptom Category Signs to Watch Action Required
Hyperthyroid Relapse Palpitations, tremor, heat intolerance, weight loss Contact GP within 1-2 days
Drug Side Effects Sore throat, fever, mouth ulcers, rash Stop medication, urgent medical review
Eye Symptoms Double vision, eye pain, swelling, vision changes Ophthalmology referral within 2 weeks
Hypothyroid Development Fatigue, cold intolerance, weight gain, depression TFTs within 1-2 weeks
Aboriginal and Torres Strait Islander Health Considerations
Follow-up Accessibility
Coordinate with Aboriginal Medical Services for culturally appropriate long-term monitoring. Consider telehealth options for remote communities.
Medication Access
Ensure PBS medication access through Section 100 Remote Area Aboriginal Health Services. Provide medication charts in appropriate languages.
Family-Centred Care
Include family members in education about symptom recognition and medication importance. Respect cultural decision-making processes.
📞
Referral Triggers: Refer to endocrinologist for: treatment failure after 6 months, pregnancy planning, recurrent relapses, complicated thyroid eye disease, or consideration for definitive therapy (RAI/surgery).