Levothyroxine is a very common medicine used to treat thyroid problems, especially a condition called hypothyroidism.
This condition happens when the thyroid gland does not make enough hormones. Levothyroxine works by giving the body the hormone it needs. Many people in the United States take this medicine, showing how common thyroid issues are.
Even though levothyroxine helps a lot of people, a new study from the University of Michigan warns that if the treatment is not carefully managed, it may increase the chance of dying from heart disease. Heart disease is already the top cause of death in the U.S., so this new research is very important.
The study, led by Dr. Maria Papaleontiou and published in JAMA Network Open, looked at more than 705,000 U.S. veterans who were treated with thyroid hormone between 2004 and 2017. The results were concerning. Up to half of these patients had thyroid hormone levels that were either too high or too low. This imbalance can be dangerous for the heart.
The researchers paid special attention to a hormone called TSH, short for thyrotropin. This hormone helps control how the thyroid works. When TSH levels are too low, it usually means the person has too much thyroid hormone in their body—a problem called exogenous hyperthyroidism.
This often happens when someone is taking too much levothyroxine. On the other hand, if TSH levels are too high, it means there isn’t enough thyroid hormone, usually from not taking enough medication.
Both situations—too much or too little thyroid hormone—can be harmful. The heart might beat too fast or too slow, or blood pressure may become harder to manage.
The study found that people with TSH levels lower than 0.1 or higher than 20 (measured in mIU/L) had the highest risk of dying from heart problems. Older adults were at even greater risk because they are more sensitive to changes in hormone levels.
To make the results more accurate, the researchers made sure to exclude patients who had other conditions like thyroid cancer or were taking drugs like lithium or amiodarone, which can affect thyroid hormone levels.
This study shows that treating thyroid disease isn’t just about replacing a missing hormone. It’s about finding the right balance. If the medication is too strong or too weak, it can lead to serious heart problems. But the good news is that this risk can be avoided. By checking TSH levels regularly and adjusting the dose, doctors can help patients stay safe.
The research highlights how closely the thyroid and heart are connected. It also shows that treatment should be tailored to each person, especially older adults. Regular doctor visits and blood tests are important to keep thyroid levels in a safe range.
If you or someone you know is taking levothyroxine, it’s important to follow up with a doctor, even if you feel okay. Hormone levels can be off without obvious symptoms. Keeping your TSH levels healthy can protect both your thyroid and your heart.
Other research has shown that diet and supplements also affect heart health. For example, eating eggs might lower heart disease risk, while some herbal products may hurt your heart rhythm. Vitamin C could lower the risk of heart failure, though vitamin E does not have the same benefit. Even espresso coffee may change cholesterol levels.
In the end, this study reminds us that small changes in how a medicine is used can make a big difference. With careful check-ups and adjustments, people with thyroid conditions can manage their health better and lower the risk of serious heart problems.
If you care about health, please read studies about the benefits of low-dose lithium supplements, and what we know about egg intake and heart disease.
For more health information, please see recent studies about potatoes and high blood pressure, and results showing 6 best breads for people with heart disease.
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