(ik weet niet of ik het juist hebt vertaald ?)
Deze analyse is uitgevoerd middels 11 studies in Europa, Australie en de Ver. Staten.
Nieuwsbericht van de AHA (American Heart Association)
Irregular heartbeat linked to higher thyroid hormone levels
October 23, 2017
• Individuals with higher levels of thyroid hormone (free thyroxine or FT4) circulating in the blood were more likely than individuals with lower levels to develop irregular heartbeat, even when the levels were within normal range.
• Blood levels of thyroid-stimulating hormone (TSH), which regulates the production of thyroid hormones and is primarily measured in clinical practice to assess thyroid function, however, were not associated with an increased risk of irregular heartbeat.
• These findings suggest that blood levels of thyroid hormone (FT4) could help identify individuals at risk for irregular heartbeat, although more research is needed before recommending routine measurement of thyroid hormones.
Individuals with higher levels of thyroid hormone (free thyroxine, FT4) circulating in the blood were more likely than individuals with lower levels to develop irregular heartbeat, or atrial fibrillation, even when the levels were within normal range, according to new research in the American Heart Association’s journal Circulation.
“Our findings suggest that levels of the thyroid hormone, free thyroxine, circulating in the blood might be an additional risk factor for atrial fibrillation,” said study lead author Christine Baumgartner, M.D., specialist in General Internal Medicine from the University Hospital of Bern, Switzerland, and currently a postdoctoral scholar at University of California San Francisco.
“Free thyroxine hormone levels might help to identify individuals at higher risk.”
In the United States, irregular heartbeat (atrial fibrillation) affects between 2.7 to 6.1 million people and is estimated to affect up to 12.1 million people by 2030. It occurs when the two upper chambers of the heart, called the atria, beat irregularly and faster than normal.
Symptoms may include heart palpitations, dizziness, sweating, chest pain, anxiety, fatigue during exertion and fainting, but sometimes patients with atrial fibrillation have no symptoms at all. Although people can live with irregular heartbeat, it can cause chronic fatigue and increase the risk of serious illnesses, such as stroke and heart failure, potentially associated with lifelong disability and even death. Fortunately, medication and other therapies are available to treat irregular heartbeat and reduce the risk of the associated symptoms and complications.
The thyroid gland is a small gland in the neck. In response to thyroid-stimulating hormone released by the pituitary gland, the thyroid gland secretes thyroid hormones required to regulate energy metabolism. Patients with low levels of thyroid hormone, or hypothyroidism, may require medications containing thyroid hormone (thyroxine) to increase their hormonal levels. Sometimes intake of thyroxine sometimes can increase these levels too much.
Previous studies showed that the risk of irregular heartbeat is greater among individuals who produce too much thyroid hormone than among those with normal hormonal levels. What was unclear, however, was whether levels that were high but still within the normal range could also increase the risk of irregular heartbeat.
To understand this relationship, investigators looked at the occurrence of irregular heartbeat among individuals with thyroid hormone levels that were still within normal range. They found that individuals with higher blood levels of FT4 within the normal range at the beginning of the study were significantly more likely than those with lower levels to subsequently develop irregular heartbeat.
When separated into four equal-sized groups, the group with the highest FT4 levels had a 45 percent increased risk of irregular heartbeat, compared to the group with the lowest levels.
Even more modest increases in thyroid hormone were associated with an increased risk.
Among individuals with the second highest levels, the risk was 17 percent greater, and among those with the third highest levels the risk was 25 percent greater, compared to those with the lowest levels.
High levels of thyroid-stimulating hormone (TSH) within the normal range, however, were not associated with an increased risk of atrial fibrillation.
“Patients who are treated with thyroxine, one of the most frequently prescribed drugs in the United States, generally have higher circulating free thyroxine levels compared to untreated individuals,” Baumgartner said. “So, an important next step is to see whether our results also apply to these patients, in order to assess whether target free thyroxine thyroid hormone concentrations for thyroid-replacement therapy need to be modified.”
The investigators analyzed data from 11 studies from Europe, Australia, and the United States that measured thyroid function and the occurrence of irregular heartbeat. Overall, the studies included 30,085 individuals. Their average age was 69 years, and slightly more than half were women. On average, follow-up ranged from 1.3 to 17 years. The investigators obtained the studies by searching the MEDLINE and EMBASE medical databases through July 2016.
http://newsroom.heart.org/news/irregula ... one-levels
Thyroid Function Within the Normal Range, Subclinical Hypothyroidism and the Risk of Atrial Fibrillation
Christine Baumgartner, Bruno R. da Costa, Tinh-Hai Collet, Martin Feller, Carmen Floriani, Douglas C. Bauer, Anne R. Cappola, Susan R. Heckbert, Graziano Ceresini, Jacobijn Gussekloo, Wendy P. J. den Elzen, Robin P. Peeters, Robert Luben, Henry Völzke, Marcus Dörr, John P. Walsh, Alexandra Bremner, Massimo Iacoviello, Peter Macfarlane, Jan Heeringa, David J. Stott, Rudi G. J. Westendorp, Kay-Tee Khaw, Jared W. Magnani, Drahomir Aujesky, Nicolas Rodondi
and for the Thyroid Studies Collaboration
1. Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
2. Institute of Primary Health Care (BIHAM), University of Bern, Bern, Switzerland
3. Service of Endocrinology, Diabetes and Metabolism, University Hospital of Lausanne, Lausanne, Switzerland
4. Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland & Institute of Primary Health Care (BIHAM), University of Bern, Bern, Switzerland
5. Departments of Medicine and Epidemiology & Biostatistics, University of California, San Francisco, San Francisco, CA
6. University of Pennsylvania School of Medicine, Philadelphia, PA
7. Department of Epidemiology, University of Washington, Seattle, WA
8. Department of Clinical and Experimental Medicine, Geriatric Endocrine Unit, University Hospital of Parma, Parma, Italy
9. Department of Public Health and Primary Care, and Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands 10
10. Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, The Netherlands
11. Departments of Internal Medicine and Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
12. Department of Public Health and Primary Care, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
13. Institute for Community Medicine, Clinical-Epidemiological Research, University Medicine Greifswald, Greifswald, Germany and German Centre for Cardiovascular Research (DZHK), partner site Greifswald, Greifswald, Germany
14. Department of Internal Medicine, University Medicine Greifswald, Greifswald, Germany and German Centre for Cardiovascular Research (DZHK), partner site Greifswald, Greifswald, Germany
15. School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia & Department of Endocrinology & Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
16. School of Population Health, University of Western Australia, Crawley, WA, Australia
17. Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
18. Institute of Health and Wellbeing, University of Glasgow, Glasgow, United Kingdom
19. Department of Epidemiology and Biostatistics, Erasmus Medical Center, Rotterdam, The Netherlands
20. Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
21. Department of Public Health and Center for Healthy Ageing, University of Copenhagen, Copenhagen, Denmark
22. Heart and Vascular Institute, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland firstname.lastname@example.org
Atrial fibrillation (AF) is a highly prevalent disorder leading to heart failure, stroke, and death. Enhanced understanding of modifiable risk factors may yield opportunities for prevention.
The risk of AF is increased in subclinical hyperthyroidism, but it is uncertain whether variations in thyroid function within the normal range or subclinical hypothyroidism are also associated with AF.
We conducted a systematic review and obtained individual participant data from prospective cohort studies that measured thyroid function at baseline and assessed incident AF.
Studies were identified from MEDLINE and EMBASE databases from inception to July 27, 2016.
The euthyroid state was defined as thyroid-stimulating hormone (TSH) 0.45 to 4.49 mIU/L, and subclinical hypothyroidism as TSH 4.5 to 19.9 mIU/L with free thyroxine (fT4) levels within reference range.
The association of TSH levels in the euthyroid and subclinical hypothyroid range with incident AF was examined by using Cox proportional hazards models.
In euthyroid participants, we additionally examined the association between fT4 levels and incident AF.
Of 30 085 participants from 11 cohorts (278 955 person-years of follow-up), 1958 (6.5%) had subclinical hypothyroidism and 2574 individuals (8.6%) developed AF during follow-up.
TSH at baseline was not significantly associated with incident AF in euthyroid participants or those with subclinical hypothyroidism.
Higher fT4 levels at baseline in euthyroid individuals were associated with increased AF risk in age and sex-adjusted analyses (hazard ratio, 1.45; 95% confidence interval, 1.26-1.66, for the highest quartile versus the lowest quartile of fT4; P for trend ≤0.001 across quartiles).
Estimates did not substantially differ after further adjustment for preexisting cardiovascular disease.
In euthyroid individuals, higher circulating fT4 levels, but not TSH levels, are associated with increased risk of incident AF.
http://circ.ahajournals.org/content/ear ... 117.028753