Association Between Educational Attainment and Thyroid Function: Results From Mendelian Randomization and the NHANES...

Area of Science:

• Endocrinology
• Genetics
• Public Health

Background:

• Observational studies suggest a link between educational attainment (EA) and thyroid function.
• The causal nature of this association and potential mediating factors remain unclear.

Purpose of the Study:

• To investigate the causal effect of educational attainment (EA) on thyroid function.
• To quantify the mediating roles of modifiable risk factors, such as smoking, in the EA-thyroid function relationship.

Main Methods:

• Two-sample Mendelian randomization (MR) using genome-wide association study (GWAS) summary statistics.
• Assessed EA's effect on thyrotropin (TSH), free thyroxine (FT4), hypothyroidism, and hyperthyroidism.
• Multivariable MR and National Health and Nutrition Examination Survey (NHANES) data analyzed mediating effects of smoking, blood pressure, and BMI.

Main Results:

• EA was causally associated with TSH (β = .046; P = 4.00 × 10-3), but not FT4, hypothyroidism, or hyperthyroidism.
• Smoking partially mediated the EA-TSH association, accounting for 10.38% of the effect in MR analysis.
• NHANES data showed a dose-response relationship between TSH and EA, with smoking, systolic blood pressure, and BMI as significant partial mediators.

Conclusions:

• A potential causal association exists between educational attainment and TSH levels.
• Modifiable risk factors, particularly smoking, play a significant mediating role in the relationship between EA and TSH.