Association of thyroid function, within the euthyroid range, with cardiovascular risk: The EPIPorto study

Area of Science:

• Endocrinology
• Cardiology
• Public Health

Background:

• Thyroid hormones significantly influence cardiovascular function.
• Both hypothyroidism and hyperthyroidism increase cardiovascular risk.
• The association between euthyroid thyroid hormone levels and cardiometabolic risk is not well-established.

Purpose of the Study:

• To investigate the relationship between thyroid function within the euthyroid range and cardiovascular risk.
• To analyze associations with cardiovascular risk factors in a population-based cohort.

Main Methods:

• Included 835 participants aged ≥45 from the EPIPorto cohort.
• Excluded individuals with abnormal thyroid function tests or pre-existing cardiovascular/thyroid disease.
• Utilized regression models to assess associations between thyroid function, risk factors, and 10-year cardiovascular event risk (SCORE2/SCORE2-OP).

Main Results:

• Higher BMI, waist circumference, and hs-CRP correlated with increased free T3 (FT3) and FT3/FT4 ratio.
• Lower FT3/FT4 ratio and higher FT4 were linked to higher diabetes prevalence and adverse lipid profiles.
• Lower FT3, lower FT3/FT4 ratio, and higher FT4 were associated with reduced eGFR and increased 10-year cardiovascular event risk.

Conclusions:

• Thyroid function variations within the euthyroid range are associated with cardiovascular risk factors.
• Reduced conversion of T4 to T3 (lower FT3, lower FT3/FT4, higher FT4) correlates with adverse cardiometabolic profiles.
• These findings highlight the importance of thyroid function even within the euthyroid range for cardiovascular health.