Characteristics of subclinical thyroid dysfunction in coastal communities in Malaysia

• Main Authors: Shahar, Mohammad Arif, Saud Ghani, Siti Liyana, Omar, Ahmad Marzuki, Abdul Wahab, Norasyikin, Sukor, Norlela, Kamaruddin, Nor Azmi
• Format: Conference or Workshop Item
• Language: English
• Published: Malaysian Endocrine & Metabolic Society (MEMS) 2016
• Subjects: RC Internal medicine
• Online Access: http://irep.iium.edu.my/52037/1/characteristics%20of%20subclinical%20thyroid%20dysfunction.pdf; http://irep.iium.edu.my/52037/; http://www.jmems.org

Objectives. To describe the characteristics of subclinical thyroid disorders in the coastal communities of Malaysia. This study is part of a nationwide study looking into the prevalence of thyroid disorders. Methods. A cross sectional study was performed in Tanjong Karang and Kuala Selangor, Selangor - two coastal villages in rural West Coast (WC) and Kuantan, Pahang - a city in the East Coast (EC) of Malaysia. A participant from each household from each villages/city was selected using KISH tables. Sociodemographic data, medical history, anthropometric measurements were recorded. Blood withdrawn was tested for thyroid function test. Serum thyroid stimulating hormone (TSH) was measured using a third generation chemiluminescent immunoassay with a detection limit of 0.01 mIU/L. TSH level of less than 0.32 mIU/L was considered hyperthyroid. Hypothyroidism is defined as TSH level of more than 5.00 mIU/L. Thyroid antibodies analyses were done using Immulite 2000 system. Lowest detectable limit for anti-thyroperoxidase (antiTPO) and anti-thyroglobulin (antiTG) are 10 IU/mL and 20 IU/mL respectively. Low, moderate and high titre was defined 40 - 100 IU/mL, 101-1000 IU/mL and >1000 IU/mL respectively. Results. Nine hundred and four respondents consented to participate in the study. Forty five point nine percent (45.9%) were from the West Coast population. Majority was female and of Malay ethnicity. A total of 895 blood samples were available for thyroid level assessment. The prevalence of subclinical hyperthyroidism and hypothyroidism were 26.8 and 13.4 per 1000 population respectively (p = 0.907). The mean age for those with subclinical hyperthyroidism is younger compared to subclinical hypothyroidism (48.71 ± 16.87 versus 54.75 ± 17.50 years old). Female forms the majority of respondents with subclinical thyroid disorders. Those with subclinical hyperthyroidism have significantly lower T4 level compared to those with subclinical hypothyroidism (14.88 ± 3.31 versus 11.94 ± 1.27 pmol/L, p < 0.001). Among respondents with subclinical hyperthyroidism, 16.6% had palpable goitre, 8.3% had palpable thyroid nodule, 8.3% had mild positive and 12.5% had moderate antiTG titre. Twenty point eight percent (20.8%) and 4.2% had moderate and strong positive antiTPO, respectively. Among respondents with subclinical hypothyroidism, none had clinically palpable goitre or thyroid nodule, 16.7% had moderate and 25% had strong positive antiTG titre. Eight point three percent (8.3%) had mild and 16.7% had moderate and strong positive antiTPO titres. Conclusion. The prevalence of subclinical hyperthyroidism and subclinical hypothyroidism was 26.8 and 13.4 per 1000 population each. Those with subclinical hypothyroidism were older compared from subclinical hyperthyroidism. Majority of respondents with subclinical thyroid disorders had no goitre and were thyroid antibodies negative.