From the Guidelines
For a patient with subclinical hyperthyroidism (low TSH with normal free T4) and bilateral thyroid nodules classified as TR3, the next steps should include both monitoring the thyroid function and evaluating the nodules. First, repeat thyroid function tests in 4-6 weeks to confirm the subclinical hyperthyroidism, as transient TSH suppression can occur 1. For the thyroid nodules, fine needle aspiration (FNA) biopsy is recommended for TR3 nodules ≥1.5 cm, as this classification indicates intermediate suspicion for malignancy. Additionally, a thyroid ultrasound should be performed if not already done to fully characterize the nodules' size, composition, and features. A thyroid uptake scan using radioactive iodine or technetium-99m can help determine if the nodules are functioning (hot) or non-functioning (cold), which may explain the low TSH. If the subclinical hyperthyroidism is persistent and causing symptoms like palpitations or anxiety, or if the patient has risk factors such as age >65, heart disease, or osteoporosis, treatment with low-dose methimazole (5-10 mg daily) might be considered 1. Regular follow-up every 3-6 months with thyroid function tests is essential to monitor progression, as approximately 1-2% of patients with subclinical hyperthyroidism progress to overt hyperthyroidism annually. Some key considerations in management include:
- Monitoring thyroid function closely to catch the transition to hypothyroidism, which is a common outcome for transient subacute thyroiditis
- Using beta-blockers for symptomatic relief in cases of thyrotoxicosis
- Considering endocrine consultation for additional workup and possible medical thyroid suppression in cases of persistent thyrotoxicosis
- Holding immune checkpoint inhibitor therapy until symptoms return to baseline in cases of moderate to severe symptoms.
From the Research
Patient Assessment and Diagnosis
- The patient has subclinical hyperthyroidism, defined as a low Thyroid-Stimulating Hormone (TSH) level of 0.04 and normal free Thyroxine (T4) levels of 1.2 2.
- The patient also has bilateral Thyroid Nodules (TR3), which require further evaluation to assess the risk of thyroid cancer and other complications.
- The presence of thyroid nodules and subclinical hyperthyroidism necessitates a comprehensive assessment, including clinical history, examination, serum TSH measurement, ultrasound, and fine-needle aspiration (FNA) if indicated 3.
Treatment and Management
- Treatment options for subclinical hyperthyroidism are recommended for patients at highest risk of osteoporosis and cardiovascular disease, such as those older than 65 years or with persistent serum thyrotropin level less than 0.1 mIU/L 2.
- For patients with thyroid nodules, FNA may be performed for nodules ≥ 1.0 cm depending on clinical and sonographic risk factors for thyroid cancer 3.
- Surgery is indicated for FNA findings of malignancy or indeterminate cytology when there is a high risk clinical context, and may also be indicated for suspicion of malignancy, larger nodules, especially with symptoms of mass effect, and in some patients with thyrotoxicosis 3.
- Repeat FNA under ultrasound guidance may be warranted in patients with thyroid nodules diagnosed on initial FNA as nondiagnostic and indeterminate for neoplasm, as it can yield a definitive diagnosis in the majority of cases 4.
Considerations and Further Evaluation
- The patient's low TSH level with normal total thyroid hormone levels may indicate free T4 excess, which is an indicator of biochemical hyperthyroidism 5.
- Thyroid scintigraphy is recommended if thyroid nodules are present or the etiology is unclear, to distinguish between a solitary hot nodule, a toxic multinodular goitre, or thyroiditis 2, 3.
- The patient's treatment plan should be individualized and patient-centered, taking into account the presence of thyroid nodules, subclinical hyperthyroidism, and other risk factors for complications 2.