Management of Subclinical Thyroiditis
For subclinical thyroiditis, treatment decisions should be based on TSH levels, with routine levothyroxine therapy not recommended for patients with TSH between 4.5-10 mIU/L, while treatment is reasonable for those with TSH >10 mIU/L. 1
Subclinical Hypothyroidism Management
TSH 4.5-10 mIU/L
- Do not routinely treat with levothyroxine
- Monitor thyroid function tests every 6-12 months to assess for improvement or worsening
- Consider these key factors:
- Some patients may have symptoms compatible with hypothyroidism
- A several-month trial of levothyroxine may be considered in symptomatic patients
- Continue therapy only if clear symptomatic benefit is observed
- The likelihood of symptomatic improvement is small and must be balanced against inconvenience, expense, and potential risks
TSH >10 mIU/L
- Treatment with levothyroxine is reasonable
- These patients have a higher rate of progression to overt hypothyroidism (approximately 5%)
- Treatment may prevent manifestations and consequences of hypothyroidism
- Evidence for improvement in cholesterol levels and symptoms remains inconclusive
Special Populations
Pregnant Women
- Screen TSH in pregnant women with:
- Family or personal history of thyroid disease
- Physical findings suggestive of goiter or hypothyroidism
- Type 1 diabetes mellitus
- Personal history of autoimmune disorders
- Treat pregnant women with elevated TSH using levothyroxine to restore TSH to reference range 1
- Monitor TSH every 6-8 weeks during pregnancy and adjust dosage as needed
- This recommendation is based on possible associations between high TSH and fetal wastage or neuropsychological complications
Patients Already on Levothyroxine
- When subclinical hypothyroidism is noted in treated patients, adjust dosage to bring TSH into reference range
- For patients with persistent symptoms and TSH in upper half of reference range, consider increasing levothyroxine to bring TSH to lower portion of reference range
- Adjust dosage based on patient's age and comorbidities
- Minimal TSH elevations may not require adjustment in patients who feel well, particularly those with cardiac disorders
Subclinical Hyperthyroidism Management
TSH 0.1-0.45 mIU/L
- Repeat TSH measurement for confirmation
- Measure FT4 and T3/FT3 to exclude central hypothyroidism or non-thyroidal illness
- If TSH remains 0.1-0.45 mIU/L with normal FT4/T3:
- Monitor with repeat testing at 3-12 month intervals
- Do not routinely treat all patients with mildly decreased TSH
TSH <0.1 mIU/L
- Repeat measurement with FT4 and T3/FT3 within 4 weeks
- Perform further evaluation to establish etiology (radioactive iodine uptake and scan)
- Consider treatment for subclinical hyperthyroidism due to Graves' or nodular thyroid disease
- Treatment is particularly important for patients:
- Older than 60 years
- With or at risk for heart disease
- With osteoporosis or risk factors for bone loss
Important Considerations
Drug-Induced Thyroiditis
- Certain medications can induce thyroiditis:
- Amiodarone
- Immune checkpoint inhibitors
- Interleukin-2
- Interferon-alfa
- Lithium
- Tyrosine kinase inhibitors 2
Subacute Thyroiditis
- Levothyroxine is not indicated for treatment of hypothyroidism during recovery phase of subacute thyroiditis 3
- Focus treatment on symptoms:
- Beta blockers for adrenergic symptoms in hyperthyroid phase
- NSAIDs and corticosteroids for thyroid pain 2
Clinical Pitfalls
- Distinguishing true therapeutic effect from placebo effect in individual patients is difficult
- Undetected subclinical hypothyroidism during pregnancy may adversely affect fetal development
- Patients with known nodular thyroid disease may develop overt hyperthyroidism when exposed to excess iodine (e.g., radiographic contrast agents)
- Always confirm abnormal TSH with repeat testing before initiating treatment
Remember that surveillance and clinical follow-up are recommended in all cases of thyroiditis to monitor for changes in thyroid function.