Nodules (lumps) within the thyroid gland are common and usually benign. They are more frequent in women, the elderly and in iodine-deficient areas. Thyroid nodules are often observed as an incidental finding in the course of ultrasonography of the thyroid, nodules of more than 1 cm in size are usually detected by palpation of the thyroid gland during a physical examination. Thyroid nodules may occur as a single nodule or as multiple nodules and may contain fluid (cyst). About 5 in 100 palpable thyroid nodules have a risk of becoming malignant (thyroid cancer). Thyroid nodules are often treated with thyroid hormones in order to reduce the size of the nodule. If thyroid nodules cause problems such as pressure symptoms or cosmetic complaints, surgery may be performed. Other therapies try to destroy the thyroid nodule by means of minimally invasive procedures (techniques which are less invasive than open surgery) and are usually performed on an outpatient basis.
We identified 31 randomised controlled trials for this systematic review. Altogether 2952 participants were allocated to the various intervention and comparator groups. In total, 16 studies lasting six months to five years investigated the effects of levothyroxine therapy. Eight studies lasting 1 to 12 months investigated the efficacy of injections, mostly of ethanol, into thyroid nodules from which fluid had been slowly removed. Laser therapy (one or up to three sessions) was applied to nodules in five studies lasting 6 to 12 months. Two studies investigated the application of one or two radiofrequency (high-frequency radiowaves) sessions over 6 to 12 months.
None of the interventions investigated death from any cause, the development of thyroid cancer or health-related quality of life. Nodule volume reductions were achieved by all therapies; however, the clinical relevance of this outcome is doubtful. Minimally invasive treatments resulted in improvements in pressure symptoms and cosmetic complaints. Some side effects such as light-to-moderate pain were observed after minimally invasive procedures.
Quality of the evidence
Most study results were of overall low quality, mainly because only a few people were investigated, findings were imprecise or measurements were prone to bias. Future studies should investigate more patient-important outcomes, such as health-related quality of life, and should compare minimally invasive therapies with surgery. Studies with longer follow-up periods are needed to provide evidence on the development of thyroid cancer, death from any cause and long-term side effects of treatments.
Currentness of data
This evidence is up to date as of April 2014.