From the Guidelines
Hypothyroidism is not typically associated with hypotension, but rather with mild hypertension, often diastolic, and a narrowed pulse pressure. According to the study published in Circulation in 2016 1, the hemodynamic changes typical of hypothyroidism are opposite to those of hyperthyroidism, and are accompanied by fewer symptoms and signs. The most common signs are bradycardia, mild hypertension, and a narrowed pulse pressure.
Some key points to consider:
- The low cardiac output in hypothyroidism is caused by bradycardia, a decrease in ventricular filling, and a decrease in cardiac contractility, which can lead to increased systemic vascular resistance, but not typically hypotension 1.
- Systemic vascular resistance can increase by as much as 50%, and diastolic relaxation and filling are slowed, which is more consistent with hypertension than hypotension 1.
- Clinical heart failure is rare in hypothyroidism, because the cardiac output is usually sufficient to meet the lowered systemic demands, and hypotension is not a characteristic feature of this condition 1.
In terms of treatment, thyroid hormone replacement with levothyroxine is typically used to manage hypothyroidism, and can help to normalize cardiac function and blood pressure. However, the primary goal of treatment is to normalize thyroid function, rather than to specifically address blood pressure. As thyroid function normalizes with proper treatment, cardiac output and blood pressure typically return to the patient's baseline levels.
From the Research
Hypothyroidism and Hypotension
- Hypothyroidism is often associated with hypertension, rather than hypotension, due to increased vascular resistance and cardiac dysfunction 2, 3, 4.
- Studies have shown that hypothyroidism can lead to increased peripheral vascular resistance, low cardiac output, and diastolic hypertension 3, 4.
- The relationship between hypothyroidism and blood pressure is complex, and thyroid hormone replacement therapy can lead to normalization of blood pressure in some patients, but not all 2, 4.
- There is no direct evidence to suggest that hypothyroidism causes hypotension, as the condition is more commonly associated with increased blood pressure 2, 5, 3, 4, 6.
- The effects of hypothyroidism on the cardiovascular system can lead to changes in blood pressure, but these changes are typically characterized by increased blood pressure, rather than hypotension 6.