From the Guidelines
A hot nodule with increased tracer uptake on a thyroid technetium scan typically indicates an autonomously functioning thyroid nodule, most commonly a toxic adenoma, and treatment depends on the patient's clinical status, with options including radioactive iodine (RAI) therapy, antithyroid medications, or surgery. The management of such nodules prioritizes controlling hyperthyroidism and preventing long-term complications. For symptomatic hyperthyroid patients, methimazole (starting at 10-30 mg daily based on severity) or propylthiouracil (100-300 mg daily divided into three doses) can control hyperthyroidism, as suggested by 1. Beta-blockers like propranolol (20-40 mg three to four times daily) may be added to manage symptoms while awaiting definitive treatment.
Treatment Options
- Radioactive Iodine (RAI) Therapy: Often preferred for older patients or those with comorbidities, using I-131 at doses of 10-30 mCi, as indicated by 1.
- Surgical Removal: Typically hemithyroidectomy, may be better for younger patients, large nodules (>4 cm), or when malignancy is suspected, based on guidelines from 1.
- Antithyroid Medications: For controlling hyperthyroidism before definitive treatment.
Considerations
- Hot nodules are rarely malignant (less than 5% risk), so fine needle aspiration is generally not required, as noted in 1.
- Patients should be monitored for post-treatment hypothyroidism, which may require levothyroxine replacement, a consideration emphasized by 1.
- The underlying mechanism involves mutations (typically in TSH receptor or G-protein genes) causing autonomous thyroid hormone production independent of normal regulatory feedback.
Given the most recent and highest quality evidence from 1, which provides updated guidelines for the management of thyroid nodules and cancer, the approach to a hot nodule with increased tracer uptake should prioritize symptom control, definitive treatment based on patient factors, and monitoring for potential complications.
From the Research
Implications of a Hot Nodule with Increased Tracer Uptake
- A hot nodule with increased tracer uptake on a thyroid technetium (TC-99m) scan is typically viewed as benign, but it may present with autonomous euthyroidism and has the potential to progress to hyperthyroidism 2.
- Hyperthyroidism can cause cardiac arrhythmias, heart failure, osteoporosis, and adverse pregnancy outcomes, and may lead to unintentional weight loss and increased mortality 3.
- The most common causes of hyperthyroidism are Graves disease, toxic multinodular goiter, and toxic adenoma, with toxic nodules being a less common cause 4.
Treatment Options
- Treatment options for a hot nodule with increased tracer uptake include:
- The choice of treatment depends on the underlying diagnosis, the presence of contraindications to a particular treatment modality, the severity of hyperthyroidism, and the patient's preference 4.
Malignancy Risk
- Hyperfunctioning or hot nodules are thought to be rarely malignant, but the incidence of malignancy is not zero 5.
- The odds of malignancy are reduced by 55% in hot nodules compared to non-toxic nodules, but the incidence of malignancy reported in hot nodules was higher than expected 5.
- Thyroid nodules with suspicious ultrasonography features, particularly hypoechoic appearance and macrocalcification, should be evaluated with fine-needle aspiration biopsy (FNAB) irrespective of the time elapsed after RAI treatment 6.