Hypothyroidism as a risk factor for cardiovascular disease

Area of Science:

• Endocrinology
• Cardiology
• Internal Medicine

Background:

• Hypothyroidism is linked to increased cardiovascular risk, encompassing functional abnormalities and atherosclerosis.
• Cardiovascular changes are observed in both subclinical and overt hypothyroidism, indicating thyroid hormone deficiency impacts the cardiovascular system.
• Impaired endothelial function, diastolic dysfunction, and reduced exercise capacity are common in hypothyroid patients.

Purpose of the Study:

• To investigate the cardiovascular risks associated with hypothyroidism, including functional abnormalities and atherosclerosis.
• To evaluate the reversibility of these cardiovascular abnormalities with L-thyroxine replacement therapy.
• To determine if the benefits of treating mild thyroid failure outweigh the risks.

Main Methods:

• Review of autopsy and epidemiological studies on thyroid hormone deficiency and cardiovascular risk.
• Assessment of cardiovascular parameters such as endothelial function, systolic and diastolic function, blood pressure, and systemic vascular resistance.
• Analysis of traditional and emerging risk factors for atherosclerosis in hypothyroid patients, including lipid profile, C-reactive protein, homocysteine, arterial stiffness, and coagulation parameters.

Main Results:

• Hypothyroid patients exhibit impaired endothelial function, diastolic dysfunction, and reduced physical capacity, which improve with L-thyroxine therapy.
• Atherosclerosis risk is elevated, associated with hypertension, atherogenic lipid profiles (especially with TSH >10 mU/L), and other factors like elevated C-reactive protein and homocysteine.
• Cardiovascular abnormalities are present even in mild thyroid failure (TSH levels <10 mU/L) and are reversible with treatment.

Conclusions:

• The cardiovascular system is significantly affected by hypothyroidism, manifesting as functional abnormalities and increased atherosclerosis risk.
• L-thyroxine replacement therapy effectively reverses these detrimental cardiovascular changes, even in cases of mild thyroid failure.
• The benefits of treating hypothyroidism with L-thyroxine outweigh the risks, highlighting the importance of timely intervention.