Dear Editor,
The ocular involvement due to disorders of the thyroid gland, termed as thyroid-associated ophthalmopathy (TAO), is due to an autoimmune process. TAO is otherwise known as Graves’ ophthalmopathy (GO), as Graves’ disease (GD) is the most common cause among all the other thyroid disorders to have ophthalmopathy.[1,2] The prevalence of TAO in southern part of India is not known. TAO as a component of GD has been extensively studied; however, there are very few studies on TAO in hypothyroidism and euthyroidism.[3,4,5] So, we undertook a cross-sectional study to know the prevalence, socio-demography, and severity of TAO in adult thyroid patients. A total of 378 adult patients (>18 years) with different thyroid disorders who visited the outpatient department between November 2013 and August 2015 were included. Thyroid patients who had other immunological disorders were excluded. Diagnosis of thyroid dysfunction was based on history, clinical examination, and thyroid hormone (T3, T4, and Thyroid stimulating hormone [TSH]) levels. Enzyme-linked immunosorbent assay (ELISA) test (second generation) was used to quantitate TRAb antibody (BioVendor Research and Diagnostic Products, Karásek, Czech Republic); >1.5 IU/L was considered positive. Anti-thyroid peroxidase (anti-TPO) antibody (Calbiotech, California, USA) was tested using ELISA; >55 IU/mL was considered positive. These tests were performed in TAO patients based on their primary disease condition.
Mean age of the patients with TAO was 41.77 years. Also, 86.5% (n = 327) of patients in our study were females. Most common thyroid disease was primary hypothyroidism (64%; n = 262) followed by GD (21%; n = 79). The prevalence of TAO was 17.5% (n = 66). Unilateral eye disease was seen in 12.1% of patients (n = 8/66). The most common sign was lid retraction seen in 91% of the cases (n = 60/66). Proptosis was noted in 40% of the cases (n = 26/66). Restrictive myopathy was seen in 30.3% of the cases (n = 20/66). Optic neuropathy was seen in two cases. Of those with TAO, 71% were hyperthyroid (n = 47), 26% were hypothyroid (n = 17), and 3% were euthyroid (n = 2). TAO was found in 48% of GD cases (n = 38/79), 6.5% of hypothyroidism patients (n = 17/262), and 25% of euthyroid disease (2/8). Severe disease was seen in 3% of the cases, and hypothyroidism never caused severe eye disease. Active TAO was seen in 6% of patients (4/66). Thirty-three percent (17/51) of males had TAO compared to 15% of females (49/327). We inferred that males had 2.24 times increased risk of TAO compared to females (95% confidence interval [CI] 1.396–3.545). Also, 50% (13/26) of the smokers had TAO compared to 15% (40/392) of nonsmokers. Smokers had three times higher risk for TAO (95% CI 2.102–5.247). There was no significant association between family history and TAO (P value of 0.181; 95% CI 0.851–2.358). Dry eye complicated 58% of TAO cases. TRAb positivity rate was 97% in GD with TAO (n = 30/31) compared to 73% (n = 16/22) in non-TAO GD patients. Anti-TPO antibody level compared in GD with and without TAO did not show any significant difference. To summarize, TAO is common in hyperthyroidism compared to hypothyroidism. TAO is complicated significantly by dry eye, which emphasizes the need for routine screening and protection of ocular surface. Male gender and smoking increase the risk of TAO. TRAb antibody positivity could serve as a useful predictor of TAO in GD.
Declaration of patient consent
The consent for publication of data has been obtained from all the patients.
Financial support and sponsorship
JIPMER Intramural grant (JIP/Res/Intra-MD/MS/01/2014: project serial number-157).
Conflicts of interest
There are no conflicts of interest.
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