Depending on the nodule’s size, a fine-needle aspiration is also recommended as the first step for further diagnosis starting from EU-TIRADS 3.

Benign nodules (TIRADS 2 and 3) are treated with an antiproliferative (inhibition of tissue growth) therapy. The most effective treatment is a combination of iodine and thyroid hormones. The dose of the thyroid hormone is adjusted to keep the TSH in the lower normal range. In older patients and patients with heart disease, the risk of heart rhythm disturbances is increased. For these patients, it is recommended to reduce the dose of the thyroid hormone and set the TSH in the middle to upper normal range. Annual ultrasound check-ups are sufficient.

Nodules classified as TIRADS 4A, B should be further evaluated with a fine-needle aspiration biopsy. A fine-needle aspiration biopsy does not rule out malignancy with 100% certainty. When performed well, there is a 60 to 80% certainty that there is no malignant tumor. The further approach depends on the physiological age of the patient. Due to the residual risk, younger patients should be histologically evaluated. If the fine-needle aspiration biopsy shows no evidence of malignancy, only the nodule is removed or, depending on its size, a hemithyroidectomy is performed. If a suspicious finding is obtained, a thyroidectomy is performed immediately, as follow-up treatment with radioiodine therapy is required for follicular or papillary thyroid carcinoma. Even if the patient desires surgery, a fine-needle aspiration biopsy is recommended beforehand. A fine-needle aspiration biopsy is a minor procedure that takes only a few minutes. If a malignancy is present, this can avoid a second intervention in 60 to 80% of cases. If the pathologist finds a malignancy after removal of the nodule or after a hemithyroidectomy, the remaining thyroid tissue must be removed within a few days to allow follow-up treatment with radioiodine therapy. In 9 out of 10 cases, a second intervention can be avoided through fine-needle aspiration biopsy.

For superficially located nodules, elastography can be helpful in deciding on the indication for surgery. For deep-seated nodules, elastography is unreliable. A single determination of calcitonin to rule out medullary thyroid carcinoma is also recommended. A scintigraphy should also be performed to rule out an autonomous adenoma. Scintigraphy is performed with radioactive technetium. Iodine has a long half-life and thus a higher radiation exposure and is only used for diagnostic scintigraphy and radioiodine therapy in tumors. If there is a decreased uptake of technetium in the area where a nodule is seen on ultrasound, it indicates a cold nodule. A cold nodule is not an indication for surgery per se.