What are the recommendations for managing thyroid dysfunction, including hypothyroidism and hyperthyroidism?

Management of Thyroid Dysfunction: Hypothyroidism and Hyperthyroidism

TSH with Free T4 testing is the cornerstone of thyroid dysfunction diagnosis, with treatment decisions based on laboratory values, symptoms, and patient risk factors. 1

Diagnostic Approach

Initial Testing

• TSH is the primary screening test for thyroid dysfunction with high sensitivity (98%) and specificity (92%) 2
• Always pair TSH with Free T4 measurement for accurate diagnosis, especially in symptomatic patients 1
• Multiple tests over 3-6 months are recommended to confirm abnormal findings before initiating treatment 1
• Consider checking thyroid antibodies (anti-TPO, anti-TG) to identify autoimmune thyroid disease 1

Interpretation of Results

• Hypothyroidism:

  • Elevated TSH with low Free T4: Overt primary hypothyroidism
  • Elevated TSH with normal Free T4: Subclinical hypothyroidism
  • Low TSH with low Free T4: Central (secondary) hypothyroidism - requires pituitary evaluation 1

• Hyperthyroidism:

  • Suppressed TSH (<0.1 mIU/L) with elevated Free T4/T3: Overt hyperthyroidism
  • Suppressed TSH with normal Free T4/T3: Subclinical hyperthyroidism 3

Treatment of Hypothyroidism

Levothyroxine Therapy

• Dosing Guidelines:

  Population	Starting Dose	Target TSH Range
  Patients under 70 without cardiac disease	1.6 mcg/kg/day	0.5-2.0 mIU/L
  Elderly or those with cardiac conditions	25-50 mcg/day	1.0-4.0 mIU/L
  Pregnant women	Adjusted to restore TSH to reference range	0.5-2.0 mIU/L
  1

• Administration:

  • Take as a single dose on an empty stomach, 30-60 minutes before breakfast 4
  • Avoid taking within 4 hours of iron, calcium supplements, or antacids which decrease absorption 4

Treatment Thresholds

• Overt Hypothyroidism: Always treat with levothyroxine 1
• Subclinical Hypothyroidism:
  • TSH >10 mIU/L with normal FT4: Treatment recommended 1
  • TSH between normal and 10 mIU/L: Consider treatment based on symptoms and risk factors 1

Monitoring

• Check thyroid function 4-6 weeks after starting therapy or dose adjustment 1
• Once stable, monitor every 6-12 months or if symptoms change 1
• Adjust dose to maintain TSH within target range 1

Treatment of Hyperthyroidism

Treatment Options

1. Antithyroid Drugs (e.g., methimazole, propylthiouracil)

   • First-line treatment for Graves' disease 3
   • Monitor for side effects: agranulocytosis (sore throat, fever), hepatitis, vasculitis 1

2. Beta-Blockers (e.g., propranolol)

   • For symptom control until antithyroid drugs reduce thyroid hormone levels 1
   • Propranolol 60-80 mg orally every 4-6 hours or 1-2 mg IV for acute management 1

3. Radioactive Iodine Ablation

   • Definitive treatment for autonomous nodules or Graves' disease 3

4. Surgery

   • Option for large goiters, suspected malignancy, or pregnancy planning 3

Treatment Thresholds

• Overt Hyperthyroidism: Always treat 3
• Subclinical Hyperthyroidism:
  • Treatment recommended for patients >65 years or with persistent TSH <0.1 mIU/L due to increased risk of osteoporosis and cardiovascular disease 3

Special Considerations

Elderly Patients

• For patients over 80-85 years, treatment decisions should be individualized 1
• Target TSH range for elderly is 1.0-4.0 mIU/L 1
• Overtreatment with levothyroxine increases risk of atrial fibrillation and osteoporosis 1

Pregnancy

• Adjust levothyroxine dose to maintain trimester-specific TSH reference range 1
• Monitor TSH every 4 weeks until stable 1

Emergency Situations

• Myxedema Coma: Life-threatening emergency requiring hospitalization 1
• Thyroid Storm: Requires immediate treatment with:
  • Propylthiouracil or methimazole
  • Saturated solution of potassium iodide
  • Beta-blockers (propranolol or esmolol if hemodynamically unstable)
  • Dexamethasone
  • Supportive care (oxygen, antipyretics, monitoring) 1

Common Pitfalls

1. Overtreatment with levothyroxine

   • Can cause iatrogenic hyperthyroidism with increased risk of atrial fibrillation and osteoporosis 1, 4
   • Monitor for low TSH which suggests overtreatment 1

2. Inadequate monitoring

   • Failure to check both TSH and Free T4 can lead to missed diagnoses 1
   • Symptoms alone are insufficient for diagnosis or dose adjustment 5

3. Medication interactions

   • Many drugs affect thyroid hormone absorption and metabolism 4
   • Key interactions: iron/calcium supplements, antacids, bile acid sequestrants, proton pump inhibitors 4

4. Failure to recognize conversion between hypo- and hyperthyroidism

   • Rare but documented phenomenon of conversion from hypothyroidism to hyperthyroidism 6
   • Persistent hyperthyroid symptoms in a patient with treated hypothyroidism should prompt re-evaluation 6