Hyperthyroidism in Patients with Graves' Ophthalmopathy, and Thyroidal, Skeletal and Eye Muscle Specific Type 2 Deiodinase Enzyme Activities

Structural brain changes in hyperthyroid Graves' disease: protocol for an ongoing longitudinal, case-controlled study in Göteborg, Sweden-the CogThy project

INTRODUCTION

Cognitive impairment and reduced well-being are common manifestations of Graves' disease (GD). These symptoms are not only prevalent during the active phase of the disease but also often prevail for a long time after hyperthyroidism is considered cured. The pathogenic mechanisms involved in these brain-derived symptoms are currently unknown. The overall aim of the CogThy study is to identify the mechanism behind cognitive impairment to be able to recognise GD patients at risk.

METHODS AND ANALYSIS

The study is a longitudinal, single-centre, case-controlled study conducted in Göteborg, Sweden on premenopausal women with newly diagnosed GD. The subjects are examined: at referral, at inclusion and then every 3.25 months until 15 months. Examinations include: laboratory measurements; eye evaluation; neuropsychiatric and neuropsychological testing; structural MRI of the whole brain, orbits and medial temporal lobe structures; functional near-infrared spectroscopy of the cerebral prefrontal cortex and self-assessed quality of life questionnaires. The primary outcome measure is the change in medial temporal lobe structure volume. Secondary outcome measures include neuropsychological, neuropsychiatric, hormonal and autoantibody variables. The study opened for inclusion in September 2012 and close for inclusion in October 2019. It will provide novel information on the effect of GD on medial temporal lobe structures and cerebral cortex functionality as well as whether these changes are associated with cognitive and affective impairment, hormonal levels and/or autoantibody levels. It should lead to a broader understanding of the underlying pathogenesis and future treatment perspectives.

ETHICS AND DISSEMINATION

The study has been reviewed and approved by the Regional Ethical Review Board in Göteborg, Sweden. The results will be actively disseminated through peer-reviewed journals, national and international conference presentations and among patient organisations after an appropriate embargo time.

TRIAL REGISTRATION NUMBER

44321 at the public project database for research and development in Västra Götaland County, Sweden (https://www.researchweb.org/is/vgr/project/44321).

Clinical, Hormonal, and Ultrasound Characteristics of Patients with Newly Diagnosed Graves’ Disease And Different Thyroid Antibody Profiles

Objective: Graves’ disease (GD) is characterized by elevated TSH-receptor antibodies (TRAb) and less often – thyroid peroxidase (TPOAb) and thyroglobulin antibodies (TgAb). Our aim was to examine the hormonal and ultrasound characteristics of patients with newly diagnosed GD with differing positive thyroid antibodies.

Materials and Methods: This study included 249 patients with newly diagnosed GD (191 women, 58 men). 40.2% of them had Graves’ ophtalmopathy. The serum levels of TSH, free T4, free T3, TRAb, TPOAb, and TgAb were measured with third generation ECLIA assays (Roche Diagnostics, Switzerland). Thyroid ultrasound was performed with a Fukuda-Denshi 550 device (Fukuda Corp., Japan) and an Ultrasonix device (Ultrasonix Medical Corp., Canada). Statistical analyses were done using the SPSS 23.0 statistical package (Chicago, IL).

Results: 64% of the patients were TPOAb+ and 36% − TgAb+. One third were only TRAb+, 1/3 had two positive antibodies (TRAb + second antibody) and 1/3 – all three positive antibodies. Patients with more positive antibodies tended to be younger, had higher fT4, TRAb levels, thyroid volume but rarely had nodules on US and accompanying GO. Positive TPOAb antibodies were found in younger patients, with higher fT4 and TRAb levels, higher thyroid volume and lower prevalence of nodules and GO. The same trends were found in patients with positive TgAb.

Conclusion: The different characteristics of GD patients with varying thyroid antibody profiles may be due to a variation in the pathogenesis of the disease. An individualized clinical approach may be suitable in those cases.

Factors Predicting Time to TSH Normalization and Persistence of TSH Suppression After Total Thyroidectomy for Graves' Disease

Hyperthyroidism related to Graves' disease is associated with a suppression of TSH values which may persist after surgery in spite of a LT₄ replacement therapy at non-TSH-suppressing doses. The aim of this retrospective study was to evaluate the time to TSH normalization in a group of patients who underwent total thyroidectomy for Graves' disease receiving a LT₄ therapy dose regimen based on a previously published nomogram, and to identify possible correlations between the time to normalization of post-operative TSH values and preoperative clinical and biochemical parameters. 276 patients affected by Graves' disease who underwent surgery between 2010 and 2015, were retrospectively evaluated for clinical and biochemical parameters as well as post-surgical LT4 treatment regimen. Of the 276 subjects, 174 had initiated LT4 dosage corresponding to a previously published nomogram. 59 patients were excluded because their LT4 requirement (in mcg/kg/day) changed and deviated from the nomogram during the follow-up period, 15 patients were excluded because their TSH level was >4 mcU/ml during the first biochemical evaluation and 2 patients were excluded because they had low TSH levels potentially related to central hypothyroidism due to concomitant hypopituitarism. Therefore, 98 patients were included in our statistical analysis. TSH and FT4 were evaluated at the first post-operative assessment and during follow up until the normalization of TSH values was achieved, and then included in the analysis. During the first post-operative evaluation 2 months after surgery, 59/98 patients had TSH values in the normal range (0.4 to 4.0 mcU/ml), while 39/98 patients had a TSH value < 0.4 mcU/mL. The persistence of post-operative TSH levels < 0.4 mcU/ml was significantly correlated (p = 0.022) with longer duration of the disease. The value of anti-TSH receptor autoantibodies (TrAb) at the diagnosis of hyperthyroidism, significantly correlated (p = 0.002) with the time to TSH normalization in the group of patients with TSH < 0.4 mcU/ml at first control. This retrospective analysis confirms that in subjects who have undergone thyroidectomy for Graves' disease, time to normalization of TSH may be prolonged. Hence, the role of TSH as the "gold standard" to assess the appropriate LT₄ replacement therapy regimen during the initial months following surgery may need to be reconsidered.