A Melbourne study has shown that total thyroidectomy does not necessarily lead to weight gain despite being a common concern amongst patients.

A review of more than 100 patients treated at the Alfred Hospital from early 2013 to mid-2014 found no overall change in body weight more than 10 months after their surgery.

Patients were mostly women (73%) with a mean age of 56 years and pre-operative weight of 78.8 kg.

Body weight remained stable in 33% of patients while 32% lost weight and 35% gained weight – defined as an increase of >2% of their baseline weight.

Overall post-operative weight gain in the cohort was just 0.1 kg however the mean weight gain in the subgroup that did put on weight was 6.1 kg (8.1% of baseline weight).

The findings were irrespective of the underlying reason for surgery – mosly multi-nodular goitre, Grave’s disease, thyroid cancer or Hashimoto’s thyroiditis.

They were also independent of age, gender, pre-operative thyroid function status, thyroid medications, GP or specialist management and patient satisfaction.

Endocrine surgeon Mr James Lee, from the Alfred Hospital and Monash University, told the limbic the study showed it was difficult to predict which patients would be in the minority of those who gained weight after surgery.

“I guess the point is that not everyone is going to be completely stable but it is unpredictable and on the whole, there is no significant change more than what is age-related.”

He said weight gain was probably one of the most common concerns of patients undergoing thyroid surgery.

“Everyone, rightly or wrongly, associates thyroid with weight problems so they are obviously concerned that having surgery on their thyroid might affected their weight. The vast majority of them worry that they might put on weight. No one is ever worried that they might lose weight.”

“The key point is we are still unable to tell the patient categorically that their weight will or will not change after thyroid surgery but on average there is no significant change.”

He added that diet and lifestyle for weight management should not be affected by thyroid surgery.

“What I normally say to patients is that as long as we optimise their thyroxine replacement after surgery, it is up to them to try and manage their weight in the usual manner.”