Thyroid surgery is extremely safe, and complications are unusual. There is, furthermore, evidence to suggest that complications are less likely to occur in operations performed by specialist surgeons who perform such surgery frequently.
The most important potential complications specific to surgery on the thyroid are voice change and hypocalcaemia (low blood calcium levels).
Voice change. Minor voice changes after thyroid operations are not uncommon, and usually consist of a ‘tiring’ of the voice towards the end of the day, and an inability to project the voice, for example in shouting or singing. These changes almost always disappear after a few weeks, and often are not even noticeable except to people who use their voice professionally (eg. singers, telephonists).
More significant alterations in the voice, consisting of a more noticeable hoarseness, should occur in no more than 1 in 100 people after thyroid surgery. This occurs due to an injury to the recurrent laryngeal nerve (RLN) during the operation. The RLN is a nerve that runs very close to the thyroid gland, and controls the voicebox (larynx). Most RLN injuries recover spontaneously over time (often taking 12-18 months), but may occasionally need further minor surgical procedures to improve the voice.
Hypocalcaemia (low blood calcium levels) may occur in up to 1 in 5 people after removal of all of the thyroid gland (total thyroidectomy). It never occurs in people having only half of the thyroid removed (thyroid lobectomy). This problem occurs because the glands in the body that control blood calcium levels (parathyroid glands) are located next to the thyroid gland. Operating on the thyroid may lead to a temporary failure of these glands to control calcium levels properly.
Most people with hypocalcaemia need no specific treatment, and the problem resolves spontaneously over a few days. A small number of people will, however, develop symptoms of hypocalcaemia (most commonly, tingling or numbness in the lips and fingertips) and need calcium tablets for a few weeks after surgery. In around 1 in 50 people calcium tablets will be needed for longer periods (occasionally lifelong) after thyroid surgery.