Thyroid autoimmunity in Greenlandic Inuit

Area of Science:

• Endocrinology
• Immunology
• Population Health

Background:

• Thyroid autoimmunity prevalence varies significantly across ethnic groups and geographical locations.
• The Inuit population in Greenland presents a unique demographic for studying thyroid autoimmunity due to their distinct genetics and non-iodine-deficient status.

Purpose of the Study:

• To determine the occurrence of thyroid autoimmunity in the Greenland Inuit population.
• To investigate the relationship between lifestyle factors (smoking, diet), iodine status, and thyroid autoimmunity in this ethnic group.

Main Methods:

• A population-based cross-sectional study was conducted in Nuuk (West Greenland) and the Ammassalik district (East Greenland).
• Data on lifestyle, diet, and diseases were collected via questionnaires.
• Serum samples were analyzed for thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TGAb), and thyroid-stimulating hormone (TSH).
• Spot urine samples were used to measure iodine and creatinine levels.

Main Results:

• Thyroid autoantibodies (TPOAb or TGAb) were detected in 9.3% of Inuit women and 7.5% of men.
• Autoantibody prevalence was higher in East Greenland Inuit with greater iodine excretion (P = 0.02).
• Thyroid autoimmunity appeared more frequent in non-smokers (12.5%) than smokers (7.0%), and was strongly associated with elevated TSH levels (P < 0.001).

Conclusions:

• Thyroid autoantibodies are uncommon in the Greenland Inuit population.
• Iodine nutrition is associated with thyroid autoimmunity, similar to other populations, but sex and smoking appear to have limited influence.
• The findings suggest a potential genetic component in Inuit thyroid autoimmunity, warranting further investigation into environmental factors such as cold exposure, selenium, and persistent organic pollutants.