Total thyroidectomy: a clue to understanding the metabolic changes induced by subclinical hyperthyroidism?

Abstract

Objective

The effects of endogenous subclinical hyperthyroidism (eSCH) on heart and bone have been well documented. There are only limited data available regarding the impact of eSCH on weight regulation and lipid metabolism. Our aim was to evaluate the changes in body weight and metabolic parameters after total thyroidectomy in patients with preoperative eSCH compared with preoperative euthyroid patients (EUT).

Design

A retrospective study of 505 patients who underwent total thyroidectomy for benign multinodular goiter in an academic hospital in Brussels (Belgium) was performed.

Patients measurements

Two hundred and twenty-five patients were included (eSCH group: n=74; EUT group: n=151). The mean follow-up time was 26.1 ± 0.8 months and was similar in both groups.

Results

Absolute BMI gain was significantly greater in the eSCH group than in the EUT group (1.11 ± 0.17 vs. 0.33 ± 0.13 kg/m²; p=0.003). A significant increase in LDL cholesterol was observed in the eSCH group (16.1 ± 3.8 mg/dl; p<0.001) but not in the EUT group (0.0 ± 3.0 mg/dl; p=0.88). In a multivariate model, preoperative TSH levels were the main factor significantly associated with increases in BMI or LDL cholesterol. Postoperative median TSH levels and L-thyroxine substitution were similar in both groups.

Conclusion

After total thyroidectomy, increases in weight and serum cholesterol were observed in the eSCH group. Given that postoperative TSH levels were similar in the two groups, these observations are probably due to the correction of eSCH, suggesting a direct effect of eSCH on body weight regulation and lipid metabolism.

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