Hashimoto’s and your heart health

Healthy thyroid is important for a healthy heart. Well-balanced thyroid hormones are necessary for healthy heart and blood vessels. They regulate blood pressure, the number of heartbeats in a minute, and how elastic our blood vessels are.

by Dr. Vedrana Högqvist Tabor

What does being hypothyroid or having Hashimoto’s mean for your heart health?

Having Hashimoto’s and having an underactive thyroid can increase the chance of heart disease, heart attack, clogged blood vessels (atherosclerosis), and high blood pressure (1–5). Chances of heart problems increase with high TPO antibodies, typically seen in people diagnosed with Hashimoto’s (6–7).

What is the connection between thyroid hormones and the heart?

All the major effects the thyroid has on the heart are caused by T3, which:
1. Increases the heart rate and rhythm, changing the speed by which the heart pumps blood (8).
2. Makes it possible for new heart cells to be made (9).
3. If out of balance, can cause high blood pressure through high cholesterol levels. Cholesterol builds up in the walls of blood vessels, causing atherosclerosis, which slows down blood flow to the heart. If there is not enough blood that carries oxygen coming to the heart, one is at high risk for a heart attack (1–5, 10).
4. May cause abnormal blood clotting, potentially leading to thrombosis (5).

What to do if you have a diagnosed heart condition and are newly diagnosed with hypothyroidism or Hashimoto’s

Your doctor’s decision about starting thyroid supplement therapy will be influenced by your age, your heart diagnosis, or the risk factor of heart problems, and will usually:

  1. Start with a very low dose of thyroid replacement hormone (the lowest possible dose)
  2. If needed, increase the dose slowly within several months

In case your thyroid is removed, your doctor might give you a higher dose to compensate for a complete loss of thyroid hormones.

Can thyroid medications help to lower the risk of heart disease?

Yes, studies on this topic were done only with a synthetic T4 replacement, and have shown that T4 replacement can be helpful to restore normal heart rhythm (11–13).

Four steps how to reduce heart problems when diagnosed with Hashimoto’s:

1. Avoid processed foods, salt, and sugars
2. Adopt a daily anti-stress routine
3. Take your medication on time, and keep your thyroid hormones in check (by taking your medications and checking up with your doctor)
4. Exercise all year around to keep your weight in check and keep your heart and lungs active


  1. Vanderpump M. et al. The incidence of thyroid disorders in the community. 1995
  2. Rodondi N. et al. Subclinical hypothyroidism and the risk of coronary heart disease. 2006
  3. Ochs N. et al. Meta-analysis: subclinical thyroid dysfunction and the risk for coronary heart disease and mortality. 2008
  4. Fatourechi V. Subclinical hypothyroidism: an update for primary care physicians. 2009
  5. Baumgartner C. et al. Subclinical hypothyroidism: summary of evidence in 2014. 2014
  6. Hak A. et al. Subclinical hypothyroidism is an independent risk factor for atherosclerosis and myocardial infarction in elderly women. 2000
  7. Razvi S. et al. The influence of age on the relationship between subclinical hypothyroidism and ischemic heart disease. 2008
  8. Klein I. et al. Thyroid hormone and the cardiovascular system. 2001
  9. Kahaly GJ et al. Thyroid hormone action in the heart. 2005
  10. Liu D. et al. A cross-sectional survey of relationship between serum TSH level and blood pressure. 2010
  11. Monzani F. et al. Effect of levothyroxine on cardiac function and structure in subclinical hypothyroidism. 2001
  12. Razvi S. et al. The beneficial effect of l-thyroxine on cardiovascular risk factors, endothelial function, and quality of life in subclinical hypothyroidism. 2007
  13. Iervasi G. et al. Low-T3 syndrome. 2003
Vedrana Högqvist Tabor