Weight gain during the treatment of thyrotoxicosis using conventional thyrostatic treatment

Weight Gain and Body Composition Changes during the Transition of Thyroid Function in Patients with Graves' Disease Undergoing Radioiodine Treatment

OBJECTIVE

This study aimed at investigating the dynamic changes in the body weight and body composition in a group of patients with Graves' disease undergoing radioiodine therapy.

METHODS

Seventeen patients with Graves' disease undergoing ¹³¹I treatment and forty-three euthyroid controls were recruited. Body weight, BMI, and body composition via bioelectrical impedance were measured for the participants at baseline, hypothyroid stage, and euthyroid stage.

RESULTS

Body weight increased significantly during the transition from hyperthyroidism to euthyroidism. However, there were no significant changes in body fat %, lean mass %, and bone mineral %. The body weight of 9 patients at the euthyroid stage exceeded their premorbid weight, while the remaining 8 patients' weight did not exceed the premorbid weight. In the group with excessive weight gain, both body fat and lean mass increased significantly. However, in the group without excessive weight gain, only lean mass increased significantly. The patients with excessive weight gain had significantly higher body fat %, while lower lean mass % compared to patients without excessive weight gain at baseline and at the euthyroid stage. Moreover, body fat % of patients with excessive weight gain was significantly higher than that of controls, while lean mass % was significantly lower than that of controls. There was no difference of body fat % and lean mass % between patients without excessive weight gain and controls.

CONCLUSION

¹³¹I treatment caused significant weight gain in patients with Graves' disease. An undesirable body composition at presentation may be a risk factor for excessive weight gain after hyperthyroidism treatment.

Modulating gut microbiota in a mouse model of Graves' orbitopathy and its impact on induced disease

BACKGROUND

Graves' disease (GD) is an autoimmune condition in which autoantibodies to the thyrotropin receptor (TSHR) cause hyperthyroidism. About 50% of GD patients also have Graves' orbitopathy (GO), an intractable disease in which expansion of the orbital contents causes diplopia, proptosis and even blindness. Murine models of GD/GO, developed in different centres, demonstrated significant variation in gut microbiota composition which correlated with TSHR-induced disease heterogeneity. To investigate whether correlation indicates causation, we modified the gut microbiota to determine whether it has a role in thyroid autoimmunity. Female BALB/c mice were treated with either vancomycin, probiotic bacteria, human fecal material transfer (hFMT) from patients with severe GO or ddH2O from birth to immunization with TSHR-A subunit or beta-galactosidase (βgal; age ~ 6 weeks). Incidence and severity of GD (TSHR autoantibodies, thyroid histology, thyroxine level) and GO (orbital fat and muscle histology), lymphocyte phenotype, cytokine profile and gut microbiota were analysed at sacrifice (~ 22 weeks).

RESULTS

In ddH2O-TSHR mice, 84% had pathological autoantibodies, 67% elevated thyroxine, 77% hyperplastic thyroids and 70% orbital pathology. Firmicutes were increased, and Bacteroidetes reduced relative to ddH2O-βgal; CCL5 was increased. The random forest algorithm at the genus level predicted vancomycin treatment with 100% accuracy but 74% and 70% for hFMT and probiotic, respectively. Vancomycin significantly reduced gut microbiota richness and diversity compared with all other groups; the incidence and severity of both GD and GO also decreased; reduced orbital pathology correlated positively with Akkermansia spp. whilst IL-4 levels increased. Mice receiving hFMT initially inherited their GO donors' microbiota, and the severity of induced GD increased, as did the orbital brown adipose tissue volume in TSHR mice. Furthermore, genus Bacteroides, which is reduced in GD patients, was significantly increased by vancomycin but reduced in hFMT-treated mice. Probiotic treatment significantly increased CD25+ Treg cells in orbital draining lymph nodes but exacerbated induced autoimmune hyperthyroidism and GO.

CONCLUSIONS

These results strongly support a role for the gut microbiota in TSHR-induced disease. Whilst changes to the gut microbiota have a profound effect on quantifiable GD endocrine and immune factors, the impact on GO cellular changes is more nuanced. The findings have translational potential for novel, improved treatments. Video abstract.

Weight gain following treatment of hyperthyroidism-A forgotten tale

Hyperthyroidism causes weight loss in the majority, but its effect is variable and 10% of patients gain weight. Its treatment usually leads to weight gain and some studies have reported an excess weight regain. However, there is considerable inter-individual variability and a differential effect on body weight by different treatments, with some studies reporting more weight increase with radioiodine, and perhaps surgery, compared with anti-thyroid drugs. The excess weight regain may relate to treatment-induced hypothyroidism. Furthermore, the transition from hyperthyroidism to euthyroidism may unmask, or exacerbate, the predisposition that some patients have towards obesity. Other risk factors commonly implicated for such weight increase include the severity of thyrotoxicosis at presentation and underlying Graves' disease. Conflicting data exist whether lean body mass or fat mass or both are increased post-therapy and whether such increments occur concurrently or in a sequential manner; this merits clarification. In any case, clinicians need to counsel their patients regarding this issue at presentation. Limited data on the effect of dietary interventions on weight changes with treatment of hyperthyroidism are encouraging in that they cause significantly lesser weight gain compared to standard care. More research is indicated on the impact of the treatment of hyperthyroidism on various anthropometric indices and the predisposing factors for any excessive weight gain. Regarding the impact of dietary management or other weight loss interventions, there is a need for well-designed and, ideally, controlled intervention studies.

Relationship between thyroid dysfunction and body weight: a not so evident paradigm

Purpose

Hypothyroidism has traditionally been associated with obesity, whereas hyperthyroidism has been linked to being underweight. However, very few studies have assessed these associations. The aim of this work is to evaluate the association between thyroid dysfunction and body mass index (BMI) at baseline and after normalization of the hormone levels.

Patients and methods

A retrospective, observational study of a cohort of otherwise healthy patients that were referred for evaluation of thyroid dysfunction to the Endocrine Department of Pontevedra University Complex Hospital, Spain was conducted. We collected data of BMI and thyroid hormone levels before treatment and after normalization of thyroid function within a follow-up period of 12 months.

Results

A total of 330 patients were initially selected for the study. In order to exclude variables that for any reason could influence on BMI, 235 were excluded for further studies. Another 61 patients were also excluded because incomplete data on their medical records, failure to achieve euthyroidism, or lost to follow-up. Therefore, the eligible final study group consisted of 34 patients (17 with hypothyroidism and 17 with hyperthyroidism). No differences were observed in mean baseline BMI between hypo and hyperthyroid patients (27.07±3.22 vs 26.39±4.44, p=0.609). Overweight or obesity was observed in 76.5% and 58.8% of hypothyroid and hyperthyroid patients, respectively (p=0.23). After normalization of thyroid function, the weight of hypothyroid patients decreased from 70.93±10.06 kg to 68.68±10.14 (p=0.000), while the weight of hyperthyroid patients increased from 65.45±11.64 kg to 68.37±12.80 (p=0.000). Their mean BMI was 26.22±3.36 and 27.57±4.98 (p=0.361) for hypo- and hyperthyroid patients, respectively. 58.8% and 64.7% patients remained in the overweight/obesity range in each group (p=0.72).

Conclusion

Untreated thyroid dysfunction is not associated with BMI. Normalization of thyroid levels significantly changed the weight of patients, but remaining most patients within overweight ranges.

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

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 pre-operative eSCH compared with pre-operative patients with euthyroid (EUT).

DESIGN

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

PATIENT'S MEASUREMENTS

Two hundred and 25 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, pre-operative TSH levels were the main factor significantly associated with increases in BMI or LDL cholesterol. Post-operative 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 post-operative 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.