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Clinical Subject Page

Hyperthyroidism

Hyperthyroidism is a clinical condition caused by excessive production and release of thyroid hormones (T3 and T4) by the thyroid gland, resulting in an increased metabolic state

Also called

Thyroid Hormone Excess

ICD-10

E05.90

Specialty

Endocrine

Onset

Chronic

Reviewed

August 2026

On This Page

Overview

–Hyperthyroidism occurs when the thyroid gland produces excessive thyroid hormones, causing increasedmetabolism and stimulation of multiple body systems


–The most common causes include; Graves Disease, toxic multinodular goiter, and toxic adenoma.

–Patients commonly present with: weight loss, heat intolerance, palpitations, tremor, and anxiety

Etiology & Risk Factors

-Etiology:

Hyperthyroidism can occur due to increased thyroid hormone production or release as in :

1. Graves Disease
• Most common cause of hyperthyroidism.
• Autoimmune stimulation of TSH receptors causes increased hormone synthesis.


2. Toxic Multinodular Goiter
• Multiple autonomous thyroid nodules produce excess thyroid hormones.


3. Toxic Adenoma
• A single hyperfunctioning thyroid nodule produces excessive hormone.


4. Thyroid-Stimulating Hormone (TSH)-Secreting Pituitary Adenoma
• Rare cause of increased thyroid hormone production.
Release of Preformed Thyroid Hormones


-Thyroiditis
• Inflammation causes leakage of stored thyroid hormones

 

-Risk Factors

• Female sex
• Family history of thyroid disease
• Autoimmune disorders
• Previous thyroid disease
• Increasing age (especially toxic multinodular goiter)
• Pregnancy and postpartum period
• Excess iodine exposure
• Amiodarone

Pathophysiology

-Autoimmune stimulation, autonomous thyroid nodules, inflammation, or excess thyroid hormone intake:


→ ↑ Thyroid hormone production or release
→ ↑ T3 and T4 levels
→ ↓ Negative feedback to pituitary gland
→ ↓ TSH secretion
→ Increased metabolic activity in tissues
→ ↑ Oxygen consumption + ↑ heat production
→ Hypermetabolic state
→ Weight loss + heat intolerance + tachycardia + tremor + anxiety


-Severe uncontrolled

hyperthyroidism
→ Excess sympathetic stimulation + metabolic stress
→ Multisystem dysfunction
→ Thyroid storm

Clinical Presentation

-Symptoms:

• Weight loss despite normal or increased appetite
• Heat intolerance
• Excessive sweating
• Palpitations
• Anxiety
• Irritability
• Tremor
• Fatigue
• Insomnia

-Signs:

• Tachycardia
• Fine tremor
• Warm, moist skin
• Weight loss
• Hyperactive deep tendon reflexes
• Increased pulse pressure
• Goiter (depending on cause)
• Lid retraction
• Lid lag

History Taking

-Ask about:

• Weight loss
• Appetite changes
• Heat intolerance
• Sweating
• Palpitations
• Tremor
• Anxiety and mood changes
• Sleep disturbance
• Bowel habit changes
• Menstrual irregularities
• Muscle weakness
• Neck swelling
• Eye symptoms

Physical Examination

-General Examination

• Assess weight and BMI
• Measure pulse and blood pressure
• Measure temperature
• Assess for tremor
• Observe anxiety or agitation
• Assess hydration status

-System-Specific Examination:

-Thyroid Examination:

• Thyroid enlargement
• Nodules if present
• Thyroid tenderness in thyroiditis
• Thyroid bruit in Graves Disease

Investigations

-Biochemistry / Specific Tests

-Thyroid-Stimulating Hormone (TSH):


-Most sensitive initial test.
Findings:


• Low or suppressed TSH
Free Thyroxine (Free T4)
Findings:
• Increased in most cases.


-Free Triiodothyronine (Free T3)
Findings:
• Increased, especially in T3 toxicosis.


-Thyroid Antibodies
Used to identify autoimmune causes:
• TSH receptor antibodies (TRAb)
• Thyroid-stimulating immunoglobulins (TSI)
• Thyroid peroxidase antibodies (TPO antibodies)

 

-Imaging
Radioactive Iodine Uptake Scan


-Helps differentiate causes:

High diffuse uptake:

•Graves Disease
Focal increased uptake


• Toxic adenoma
Multiple areas of increased uptake


• Toxic multinodular goiter
Low uptake


•Thyroiditis
• Exogenous thyroid hormone use

Diagnosis

-Hyperthyroidism is diagnosed by demonstrating excess thyroid hormone activity


-Typical findings:
• Suppressed TSH
• Elevated free T4 and/or free T3


-Diagnosis of the underlying cause is based on:
• Clinical features
• Thyroid antibody testing
• Radioactive iodine uptake pattern

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Management

1. First-Line / Emergency Management

Stable Hyperthyroidism

  • Confirm diagnosis and cause.

  • Beta-blocker for symptom control.

  • Start treatment according to the cause.

Thyroid Storm

  • Beta-blocker

  • Antithyroid drug

  • Iodine after the antithyroid drug

  • Corticosteroids

  • IV fluids and supportive care

  • Treat the precipitating cause

 

2. Definitive Treatment

  • Radioactive iodine therapy: common definitive treatment for Graves Disease and toxic nodular disease.

  • Thyroidectomy: considered for large goiter, compressive symptoms, suspicious nodules/cancer, patient preference, or need for rapid control.

 

3. Medical Treatment

  • Methimazole (MMI) / Carbimazole: first-line antithyroid drugs in most patients.

  • Propylthiouracil (PTU): preferred in the first trimester of pregnancy and thyroid storm.

  • Propranolol / Atenolol: for palpitations, tremor, and anxiety.

 

4. Surgical / Procedural Treatment

Thyroidectomy for:

  • Large goiter

  • Suspected cancer

  • Unsuitable medical/radioactive iodine treatment

  • Need for rapid definitive control

 

5. Supportive Management

  • Regular thyroid function monitoring

  • Smoking cessation

  • Eye care in Graves ophthalmopathy

  • Educate about medication adverse effects

Complications

• Thyroid storm
• Severe dehydration
• Heart failure
• Arrhythmias
• Atrial fibrillation
• Cardiomyopathy
• Osteoporosis
• Muscle weakness

Prognosis

-The prognosis is generally good with appropriate diagnosis and treatment.


–Outcome depends on:
• Underlying cause
• Response to treatment
• Medication adherence
• Presence of complications
• Control of cardiovascular effects

Key Points / Clinical Pearls

• Hyperthyroidism is excessive production of thyroid hormones.
• It causes an increased metabolic state.
• The most common cause is Graves Disease.
• Typical laboratory findings are ↓ TSH + ↑ Free T4/T3.
• Common symptoms include weight loss, heat intolerance, tremor, and palpitations.
• Hyperthyroidism may cause atrial fibrillation and heart failure.
• Graves Disease may cause ophthalmopathy and pretibial myxedema.
• Beta-blockers control symptoms but do not reduce thyroid hormone production.
• Antithyroid drugs reduce thyroid hormone synthesis.
• Radioactive iodine and surgery are definitive treatment options.
• Thyroid storm is a life-threatening complication.

  • Ross DS, Burch HB, Cooper DS, et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis. Thyroid. 2016;26(10):1343-1421. Thyroid .
  • Kahaly GJ, Bartalena L, Hegedüs L, Leenhardt L, Poppe K, Pearce SH. 2018 European Thyroid Association Guideline for the Management of Graves' Hyperthyroidism. Eur Thyroid J. 2018;7(4):167-186. European Thyroid Journal .
  • De Leo S, Lee SY, Braverman LE. Hyperthyroidism. Lancet. 2016;388(10047):906-918. The Lancet .
  • Burch HB, Cooper DS. Management of Graves Disease: A Review. JAMA. 2015;314(23):2544-2554. JAMA .
  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Hyperthyroidism (Overactive Thyroid) . National Institutes of Health.
  • National Library of Medicine (NIH). Hyperthyroidism . StatPearls.