Hypothyroidism (underactive thyroid) is common and an increased TSH level and, usually, a low FT4 level make the diagnosis. Hypothyroidism is treated with thyroid hormone replacement, usually in the form of levothyroxine. The goal of treating hypothyroidism is achieving a TSH in the normal range, which is usually sufficient in relieved the symptoms of hypothyroidism. However, it is important to not over or undertreat the condition. If a TSH remains high on levothyroxine (undertreatment), the patient is likely to have continued symptoms. If the TSH is too low (overtreatment), the patient may have symptoms of hyperthyroidism.
Not keeping the levels in the normal range can increase risk for heart issues and increase the risk of death from heart disease (cardiovascular mortality). A persistently increased TSH can lead to increased levels of cholesterol, which can cause heart disease. Similarly, a persistently low TSH can lead to an increased risk for atrial fibrillation, which causes the heart to beat irregularly, and increase risk of stroke. This study looks into the association of overtreatment and undertreatment of hypothyroidism and the risk of death due to heart disease.
THE FULL ARTICLE TITLE
Evron JM et al 2022 Association of thyroid hormone treatment intensity with cardiovascular mortality among US veterans. JAMA Netw Open 5(5):e2211863. PMID: 35552725.
SUMMARY OF THE STUDY
The authors looked into data from charts from the U.S. Veterans Health Administration Corporate Data Warehouse in order to identify those receiving thyroid hormone treatments from January 1, 2004, and December 31, 2017. They also used the National Death Index to assess death rates and cause of death.