Toronto, ON – A new study published this week in Archives of Gerontology and Geriatrics Plus found that 10% of South Asian immigrants aged 45 and older in Canada had hypothyroidism. After adjustment for a wide range of sociodemographic characteristics and health behaviors, those who had immigrated from South Asia had 77% higher odds of hypothyroidism than those born in Canada.
"To the best of our knowledge, this is the first study to identify a significantly higher odds of hypothyroidism among immigrants of South Asian descent," says senior author Esme Fuller-Thomson, a Professor at Factor-Inwentash Faculty of Social Work (FIFSW) and Director for the Institute of Life Course and Aging at the University of Toronto. "Given that previous studies have identified lower thyroid screening rates among immigrants in Canada, these results emphasize the need for increased screening efforts among South Asian immigrants."
When left untreated, hypothyroidism can lead to adverse health effects such as anemia, hypertension, hypercholesterolemia, and neurologic dysfunction.
"An important area for future studies is the possibility that disproportionate rates of hypothyroidism among South Asian immigrants may be related to an endemic lack of iodine in their countries of origin," says first author ZhiDi Deng, a medical student at the University of Alberta. "Iodine deficiency is a known contributor to the development of hypothyroidism." Unfortunately, the survey used in the current study did not contain information on participant's iodine levels, so this hypothesis could not be explored.
In addition to immigrant status, the study identified diet as another important associated with hypothyroidism.
"We found that those who had a lower dietary intake of fat, or individuals with higher dietary intake of omega-3 fatty acids, fruits and vegetables, and pulses and nuts, were significantly less likely to have hypothyroidism," says co-author Karen M. Davison, a nutritional epidemiologist. "These findings shed light on a potential benefit of non-pharmacological, nutrition-based interventions in the prevention or management of hypothyroidism, although additional research is still needed."
Increasing age was also identified as a factor that increased the likelihood of hypothyroidism.
"Individuals over the age of 75 had double the prevalence of hypothyroidism compared to those aged 45-55," says co-author Andie MacNeil, a PhD student at University of Toronto's FIFSW. "Autoimmune thyroiditis is common cause of hypothyroidism among older adults and may be a driver for this increased prevalence."
This study was based on the Canadian Longitudinal Study on Aging and analyzed a sample of 26,036 Canadians between ages 45-85 years, of which 1,953 individuals had hypothyroidism.
Although early recognition and treatment of hypothyroidism are important to minimize preventable health impacts, the symptoms of hypothyroidism, such as fatigue, weight gain, and depression, are non-specific and thus it can be difficult to identify the condition without blood tests, particularly among older adults.
"This research has identified some novel potential risk and preventative factors for hypothyroidism, opening avenues for future studies," said Fuller-Thomson "We hope that the results from this research will promote increased screening for thyroid conditions among older adults, particularly among those of South Asian descent."
