Endocrine Abstracts

Introduction

Thyroid disorders are second largest endocrine condition seen in clinics. The most common manifestation of thyroid dysfunction is the appearance of goitre. The elimination of iodine deficiency as a cause of goitres decades ago has demanded a closer look into autoimmune aetiology of thyroid disease in our population. The characteristic features of these autoimmune goitres: Graves’ Disease (GD) were also explored in this study. The finding of a higher than reported prevalence of Marine Lenhart syndrome in this study raises the concern for possible induction of autonomous nodules in the presence of iodine sufficiency.

Methods

One hundred and thirty-four participants with goitres were recruited for the study. Seventy-seven of these participants with goitre had features of toxic goitre confirmed with low TSH and elevated free Thyroxine and Triiodothyronine had Thyrotropin Receptor Antibody (TRAb) assayed to determine autoimmune hyperthyroidism. Thyroid ultrasonography was carried out on all participants.

Results

The TRAb is a confirmatory test for Graves’ disease, of the 77 with clinical, radiological and /or biochemical diagnosis of Toxic goitre tested, 60 were positive with a Prevalence rate of 77.9%, of which males were 20 and females 40. The prevalence of autoimmune thyroid disease among the general population using Anti-Thyroid Peroxidase was 38.7% while among those with goitre; 53.7%. Out of 77 with toxic goitres tested, 72 had positive Anti-TPO with a prevalence of thyroid autoimmunity at 93.5%. 18 males and 54 females. Both Antibodies were positive in 48 of the 77 tested giving a prevalence of 62.3%. Among those with toxic goitre tested using TRAb, 7.6% had other clinical diagnosis other than GD as clinical /provisional diagnosis. Fifty percent of the subjects with clinically indeterminate diagnosis between Toxic Multinodular Goitre (TMG) and GD had positive TRAb result while 66.7% of those who had clinical and radiological diagnosis of TMG had positive TRAb. There is an increased prevalence of Marine Lenhart Syndrome in this study of 10% compared to previous reports of 0.8–4.1 percent

Conclusion

Diagnosis of GD (Autoimmune Hyperthyroidism) is most certain with TRAb. The use of clinical features alone is prone to misdiagnosis while isolated use of Anti-TPO for diagnosis of GD could lead to inappropriate diagnosis. The high prevalence of TRAb-positive nodular goitres raises the concern of possible association between autoimmune thyroid disease and possible iodine sufficiency in which autonomous thyroid nodules are spontaneously developed.

Keywords: autoimmune, hyperthyroidism, anti-thyroid peroxidase, thyrotropin receptor antibody, Graves’ disease