What are the symptoms and treatment options for hyperthyroidism?

Hyperthyroidism: Symptoms and Treatment

Clinical Presentation

Hyperthyroidism presents with a characteristic constellation of cardiovascular, neurological, and metabolic symptoms that should prompt immediate TSH testing. 1

Cardiovascular Symptoms

• Tachycardia and palpitations are hallmark features, often accompanied by hypertension and increased cardiac output 1, 2
• Decreased systemic vascular resistance occurs as a compensatory mechanism 1, 3
• Atrial fibrillation develops in 10-25% of hyperthyroid patients, representing a serious complication requiring anticoagulation 2
• Pulmonary artery hypertension with right ventricular dilatation can occur in severe cases 1, 2
• Heart failure may develop in severe, long-standing hyperthyroidism, particularly with persistent tachycardia or rapid atrial fibrillation 1, 3

Neurological and Psychiatric Symptoms

• Tremors (fine, rapid tremor of the hands) are nearly universal 1, 3
• Nervousness, anxiety, and hyperactivity are prominent features 1, 3
• Insomnia is common and contributes to overall symptom burden 1, 3

Metabolic and Dermatological Symptoms

• Excessive sweating and heat intolerance reflect increased metabolic rate 1, 3
• Unintentional weight loss despite normal or increased appetite 4
• Hair loss occurs in many patients 3
• Diarrhea may be present due to increased gut motility 4

Physical Examination Findings

• Goiter (diffusely enlarged thyroid) is typically palpable 1, 3
• Thyroid eye disease (stare, exophthalmos) is pathognomonic for Graves disease 4
• Muscle weakness and wasting may be evident 5

Life-Threatening Complications

• Thyroid storm is a rare but life-threatening emergency requiring immediate recognition and treatment 1, 3
• Cardiovascular complications are the chief cause of death, especially in patients over 50 years 1, 2

Treatment Approach

Immediate Symptomatic Management

Beta-blockers should be initiated immediately upon diagnosis to control cardiovascular and neurological symptoms while definitive therapy takes effect. 1, 2

• Atenolol or propranolol are first-line agents to lower heart rate to nearly normal, reduce tremors, and prevent cardiac complications 1, 2, 3
• Beta-blockers provide rapid improvement in tachycardia, palpitations, tremors, and anxiety within hours to days 2
• The goal is to achieve near-normal heart rate, which improves tachycardia-mediated ventricular dysfunction 2
• Do not use beta-blockers in patients with Wolff-Parkinson-White syndrome with preexcited ventricular activation (Class III contraindication) 2

Definitive Treatment Options

Three definitive treatment modalities exist: antithyroid drugs, radioactive iodine ablation, and surgery—each with specific indications. 5, 6

Antithyroid Medications

• Methimazole is the preferred antithyroid drug for most patients with Graves disease, toxic multinodular goiter, or toxic adenoma 5, 6, 4
• Treatment duration is typically 12-18 months for Graves disease with the goal of inducing remission 6, 7
• Propylthiouracil is reserved for specific situations: patients intolerant to methimazole, first trimester of pregnancy, or preparation for surgery/radioactive iodine when methimazole cannot be used 8
• Propylthiouracil carries significant risk of severe liver injury, hepatic failure, and death, particularly in children and pregnant women 8
• Patients on propylthiouracil must immediately report symptoms of hepatic dysfunction (anorexia, pruritus, jaundice, dark urine, right upper quadrant pain) 8
• Monitor for agranulocytosis (low white blood cell count), which typically occurs within the first 3 months and requires immediate reporting of fever, sore throat, or signs of infection 8

Radioactive Iodine Ablation

• Radioactive iodine is the most widely used treatment in the United States, resolving hyperthyroidism in >90% of patients with Graves disease and toxic multinodular goiter 5, 6
• It is the treatment of choice for toxic nodular goiter 7
• Hypothyroidism develops in most patients within 1 year after treatment, requiring lifelong thyroid hormone replacement 5
• Contraindicated in pregnancy and lactation; pregnancy should be avoided for 4 months following administration 7
• May worsen Graves ophthalmopathy; corticosteroid cover may reduce this risk 7

Surgical Thyroidectomy

• Surgery is indicated for: large obstructive goiter causing compressive symptoms (dysphagia, orthopnea, voice changes), patients refusing radioiodine, or when rapid definitive treatment is needed 5, 4, 7
• Subtotal or near-total thyroidectomy is performed with the goal of curing the disease while potentially maintaining euthyroidism 7
• Patients should be rendered euthyroid with antithyroid drugs before surgery to prevent thyroid storm 6

Special Populations

Pregnancy

• Hyperthyroidism in pregnancy increases risk of severe preeclampsia, preterm delivery, stillbirth, and heart failure 1, 3
• Propylthiouracil may be preferred during the first trimester as methimazole is associated with rare fetal abnormalities 8
• Consider switching to methimazole for second and third trimesters given propylthiouracil's maternal hepatotoxicity risk 8
• Pregnant women require careful monitoring and should contact their physician immediately about therapy 8

Subclinical Hyperthyroidism

• Treatment is recommended for patients at highest risk: those >65 years old, with persistent TSH <0.1 mIU/L, or with cardiac disease, atrial fibrillation, or osteoporosis risk 1, 4
• Postmenopausal women with prolonged subclinical hyperthyroidism require bone mineral density testing 1

Monitoring and Follow-up

• If atrial fibrillation is present, oral anticoagulation (INR 2-3) is mandatory to prevent thromboembolism 2
• Antiarrhythmic drugs and electrical cardioversion are generally unsuccessful while thyrotoxicosis persists 2
• Thyroid function tests should be monitored periodically during therapy 8
• An elevated TSH during treatment indicates the need for a lower maintenance dose of antithyroid medication 8

Critical Pitfalls to Avoid

• Do not discontinue antithyroid drugs when adding beta-blockers—both serve different purposes and must be used together 2
• Recognize that thyroiditis-induced thyrotoxicosis does not respond to antithyroid drugs and requires only supportive care 4
• Be aware that severe non-thyroid illness can cause false positive TSH results 1
• Patients with nodular thyroid disease may develop overt hyperthyroidism when exposed to excess iodine (e.g., radiographic contrast) 1