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Published on: August 18, 2015
Thyroid Hormone Therapy and Incident Stroke
Maria Papaleontiou1, Deborah A Levine2, David Reyes-Gastelum1
1Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.
Insights
Thyroid hormone treatment intensity impacts stroke risk. Both too much and too little thyroid hormone (exogenous hyper- and hypothyroidism) increase stroke incidence, emphasizing medication safety.
Area of Science:
- Endocrinology
- Cardiovascular Medicine
- Public Health
Background:
- Stroke is a major cause of death and disability worldwide.
- Identifying modifiable risk factors for stroke is crucial for prevention.
- Thyroid hormone levels are critical for metabolic regulation and cardiovascular health.
Purpose of the Study:
- To investigate the association between thyroid hormone treatment intensity and the risk of developing atrial fibrillation and stroke.
- To determine if deviations from euthyroid state in thyroid hormone users correlate with adverse cardiovascular events.
Main Methods:
- Retrospective cohort study utilizing Veterans Health Administration data (2004-2017).
- Included 733,208 thyroid hormone users (≥18 years) with at least two thyroid-stimulating hormone (TSH) or free thyroxine (T4) measurements.
- Median follow-up of 59 months to track incident atrial fibrillation and stroke.
Main Results:
- Higher stroke incidence was linked to both low TSH/high free T4 (exogenous hyperthyroidism) and high TSH/low free T4 (exogenous hypothyroidism) compared to euthyroid states.
- Specific odds ratios (OR) indicated increased stroke risk for both conditions (e.g., TSH <0.1 mIU/L: OR 1.33; TSH >5.5 mIU/L: OR 1.29).
- The risk for atrial fibrillation and stroke accumulated over time in patients with exogenous hyperthyroidism and hypothyroidism.
Conclusions:
- Both exogenous hyperthyroidism and hypothyroidism are associated with an elevated risk of stroke.
- Maintaining appropriate thyroid hormone levels is essential for patient medication safety and stroke prevention.
- This study underscores the importance of careful monitoring of thyroid hormone levels in treated patients.
Context:
Stroke is a leading cause of death and disability and there is a need to identify modifiable risk factors.
Objective:
We aimed to determine the relationship between thyroid hormone treatment intensity and incidence of atrial fibrillation and stroke.
Methods:
We conducted a retrospective cohort study using data from the Veterans Health Administration between 2004 and 2017, with a median follow-up of 59 months. The study population comprised 733 208 thyroid hormone users aged ≥18 years with at least 2 thyroid stimulating hormone (TSH) measurements between thyroid hormone initiation and incident event (atrial fibrillation or stroke) or study conclusion (406 030 thyroid hormone users with at least 2 free thyroxine [T4] measurements).
Results:
Overall, 71 333/643 687 (11.08%) participants developed incident atrial fibrillation and 41 931/663 809 (6.32%) stroke. In multivariable analyses controlling for pertinent factors such as age, sex, and prior history of atrial fibrillation, higher incidence of stroke was associated with low TSH or high free T4 levels (ie, exogenous hyperthyroidism; eg, TSH <0.1 mIU/L; OR 1.33; 95% CI, 1.24-1.43; free T4>1.9 ng/dL, OR 1.17, 95% CI 1.06-1.30) and high TSH or low free T4 levels (ie, exogenous hypothyroidism; eg, TSH >5.5 mIU/L; OR 1.29; 95% CI, 1.26-1.33; free T4 <0.7 ng/dL; OR 1.29; 95% CI, 1.22-1.35) compared with euthyroidism (TSH >0.5-5.5 mIU/L and free T4 0.7-1.9 ng/dL). Risk of developing atrial fibrillation and stroke was cumulative over time for both patients with exogenous hyperthyroidism and hypothyroidism.
Conclusion:
Both exogenous hyper- and hypothyroidism were associated with increased risk of stroke, highlighting the importance of patient medication safety.
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