What are the treatment options for thyroid disorders, including hypothyroidism and hyperthyroidism?

Treatment Options for Thyroid Disorders

Hypothyroidism Treatment

Levothyroxine monotherapy is the standard and preferred treatment for hypothyroidism, administered as a single daily dose on an empty stomach, one-half to one hour before breakfast. 1, 2, 3

Initial Dosing Strategy

• For patients under 70 years without cardiac disease: Start with full replacement dose of approximately 1.6 mcg/kg/day to rapidly normalize thyroid function 1
• For patients over 70 years or with cardiac disease/multiple comorbidities: Start with a lower dose of 25-50 mcg/day and titrate gradually to avoid cardiac complications 1, 2
• For pregnant women or those planning pregnancy: Initiate treatment immediately, as untreated hypothyroidism increases risk of preeclampsia, low birth weight, and neurodevelopmental effects in offspring 4, 2

Treatment Thresholds Based on TSH Levels

• TSH >10 mIU/L: Initiate levothyroxine regardless of symptoms, as this carries approximately 5% annual risk of progression to overt hypothyroidism 1
• TSH 4.5-10 mIU/L: Consider treatment for symptomatic patients, those with positive anti-TPO antibodies (4.3% annual progression risk), or women planning pregnancy 1
• TSH <4.5 mIU/L with normal free T4: No treatment indicated; this represents normal thyroid function 1

Monitoring and Dose Adjustment

• Check TSH and free T4 every 6-8 weeks while titrating hormone replacement until target TSH of 0.5-4.5 mIU/L is achieved 1
• Once stabilized, monitor TSH every 6-12 months or sooner if symptoms change 1
• Adjust dose in 12.5-25 mcg increments based on patient's age and cardiac status 1

Critical Safety Considerations

• Always rule out concurrent adrenal insufficiency before starting levothyroxine, especially in patients with suspected central hypothyroidism, as thyroid hormone can precipitate life-threatening adrenal crisis 1, 2
• Start corticosteroids at least 1 week before thyroid hormone in patients with coexisting adrenal insufficiency 1
• Approximately 25% of patients are unintentionally overtreated (TSH suppressed), increasing risks for atrial fibrillation, osteoporosis, fractures, and cardiac complications 1

Pregnancy-Specific Management

• Levothyroxine requirements increase by 25-50% during pregnancy in women with pre-existing hypothyroidism 2
• Monitor TSH every trimester after dosage stabilization 2
• Return to pre-pregnancy dose immediately after delivery, as postpartum TSH levels return to preconception values 2
• Levothyroxine is safe during breastfeeding and may normalize milk production in hypothyroid mothers 2

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Hyperthyroidism Treatment

Treatment options for hyperthyroidism include antithyroid drugs (thioamides), radioactive iodine ablation, and thyroid surgery, with choice depending on etiology, severity, patient preference, and contraindications. 4, 5

Antithyroid Drug Therapy

• Propylthiouracil (PTU) or methimazole are the thioamides used for hyperthyroidism treatment 4, 6
• For pregnant women: Both agents are considered acceptable, with recent studies showing no significant differences in fetal outcomes between PTU and methimazole 4
• Goal of therapy: Maintain free T4 or free thyroxine index (FTI) in the high-normal range using the lowest possible thioamide dosage 4
• Monitor free T4 or FTI every 2-4 weeks during initial treatment phase 4

Beta-Blocker Adjunctive Therapy

• Propranolol or other beta blockers can be used to reduce symptoms (palpitations, tremor, anxiety) until thioamide therapy reduces thyroid hormone levels 4

Serious Adverse Effects of Thioamides

• Agranulocytosis (life-threatening low white blood cell count) usually presents within first 3 months with fever, chills, or sore throat—discontinue drug immediately and obtain complete blood count 6
• Severe liver problems including liver failure requiring transplant or causing death—stop drug immediately if fever, nausea, vomiting, right upper abdominal pain, dark urine, pale stools, or jaundice develop 6
• Vasculitis (inflammation of small blood vessels) can affect skin, kidneys, or lungs—report skin rashes, changes in urine color or volume, or respiratory symptoms immediately 6
• Increased bleeding risk due to effects on blood clotting 6

Radioactive Iodine Therapy

• Radioactive iodine (I-131) is contraindicated in pregnant women as it can ablate fetal thyroid if exposure occurs after 10 weeks gestation 4
• Women should not breastfeed if inadvertently exposed to radioactive iodine 4

Surgical Management

• Thyroidectomy should be reserved for women who do not respond to thioamide therapy or when other treatments are contraindicated 4

Graves Disease-Specific Considerations

• Monitor pregnant women with Graves disease for normal heart rate and appropriate fetal growth 4
• Ultrasound screening for fetal goiter is not necessary unless problems are detected 4
• Inform the newborn's physician about maternal Graves disease due to risk of neonatal thyroid dysfunction 4
• Fetal and neonatal thyroid suppression from thioamides is usually transient and rarely requires treatment 4

Treatment for Subclinical Hyperthyroidism

• Treatment is recommended for patients at highest risk: those older than 65 years or with persistent serum TSH <0.1 mIU/L, due to increased risk of osteoporosis and cardiovascular disease 5

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Common Pitfalls to Avoid

• Never treat based on a single abnormal TSH value—30-60% of elevated TSH levels normalize spontaneously on repeat testing 1
• Do not start thyroid hormone before ruling out adrenal insufficiency in suspected central hypothyroidism 1
• Avoid excessive levothyroxine dosing—overtreatment occurs in 14-21% of patients and significantly increases cardiac and bone complications 1
• Never assume hypothyroidism is permanent without reassessment—consider transient thyroiditis, especially in recovery phase 1
• For patients on thioamides, immediately discontinue if fever and sore throat develop and check complete blood count for agranulocytosis 6