The Effects of Hypothyroidism on the Heart

Hormones produced by the thyroid gland have a profound effect on the heart, including both growth and function, so when a person suffers from hypothyroidism, or decreased thyroid hormone production, serious cardiac consequences can occur.

Symptoms

• Hypothyroidism slows the heart rate, and while this may not be perceptible in people with healthy hearts and mild hypothyroidism, prolonged deficiency as well as previous cardiac disease can lead to serious complications. Other heart-related symptoms include shortness of breath, peri-cardial effusion (fluid around the heart) or congestive heart failure.

Blood Pressure

• While many might assume a lower heart rate would correspond to lower blood pressure, in fact hypothyroidism causes a rise in blood pressure (hypertension) because of stiffening of the arteries.

Cholesterol

• While hypothyroidism has not been proved to directly raise the amount of LDL (bad cholesterol) in the blood, the two are often found together, and treatment of hypothyroidism usually results in a significant drop in LDL levels.

Treatment

• Treatment of hypothyroidism has been shown to help improve heart disease, but the hormone levels must be increased very slowly, or opposite symptoms may occur, such as increased heart rate, angina or palpitations.

Subclinical Hypothyroidism

• While not all these symptoms are directly controlled by the thyroid hormone, such as cholesterol and blood pressure, studies have shown that even those with very mild (subclinical) asymptomatic hypothyroidism benefit almost immediately from hormone treatment in regards to cardiac symptoms.