Highlights:
- Link
between thyroid function and atherosclerosis, found from subclinical atherosclerosis to overt disease and death
- Atherosclerosis
is a condition where there is plaque formation in arteries; it is an
underlying cause for heart attacks and strokes
- The
association seems to be independent of known cardiovascular risk factors
like age, cholesterol, blood pressure, diabetes, and smoking.
High and high-normal levels of a
thyroid hormone called thyroxine or FT4, are associated with artery disease and
death in elderly and middle-aged people, was
identified in a new research published in Circulation
Research, an American Heart Association journal
.
FT4 or
free thyroxine is a hormone produced by the thyroid gland that is responsible
for regulating metabolism. Hyperthyroidism and hypothyroidism are
thyroid diseases that are caused by increased and decreased levels of
circulating free thyroxine respectively.
‘The link between thyroid function and atherosclerotic events and deaths is independent of known cardiovascular risk factors; the connection might have unexplored pathways or other cardiovascular risk factors.’
Atherosclerosis is a disease where there is
plaque formation in the arteries. Hardened arteries are a risk factor for heart disease and stroke.
"
Coronary heart disease and
stroke remain a leading cause
of mortality worldwide, despite advances in prevention and treatment;
therefore, identifying additional modifiable risk factors for hardened blood
vessels is important" says study author Dr. Arjola Bano, M.D.,
M.Sc., D.Sc., a researcher in internal medicine and epidemiology at Erasmus
University in Rotterdam, the Netherlands.
The Rotterdam Study
The Rotterdam Study involved 9,420 participants
(average age 66 percent women) in which researchers analyzed data
to
determine the link between two types of hormones: thyroid-stimulating hormone
and free thyroxine (FT4), and atherosclerosis and death due to coronary heart
disease, cerebrovascular disease or other artery-related illness.
It is believed to be the first population-based
study that has studied the relationship between thyroid function and
atherosclerosis, from subclinical atherosclerosis (early stages of the disease)
to overt disease and death.
Asymptomatic atherosclerosis was determined by
measuring coronary artery calcification.
There was a range
of factors that could affect the results of the analysis were taken into
account; these included age, sex, body mass index (BMI), cholesterol, triglycerides, blood pressure, alcohol
consumption, diabetes, smoking, and medications for lowering
blood pressure and lipids.
The participants were followed for an average of
8.8 years. There was a
total of 934 first-time atherosclerosis-related
cardiovascular events and 612 atherosclerosis-related cardiovascular deaths.
Participants who had increased FT4 levels had
- Twice
the chance of having high levels of coronary artery calcification scores
that were considered to be an indicator of subclinical atherosclerosis
- An
87 percent greater risk of suffering an atherosclerosis-related
cardiovascular event
- Double
the risk of suffering from an atherosclerosis-related cardiovascular death
These findings were independent of the risk
factors taken into account. Researchers predict that the connection maybe
occurring via unexplored pathways or non-traditional cardiovascular risk
factors.
"We expected that thyroid function would
influence the risk of developing atherosclerosis by affecting cardiovascular
risk factors such as blood pressure. However, our results remained very similar
after accounting for several cardiovascular risk factors," said Arjola Bano.
"This suggests that
mechanisms other than traditional cardiovascular risk
factors may play a role."
Some limitations of the study were that it did
not measure the levels of FT4 over time and the participants were mostly white
middle-age adults. Hence, the results may not be applicable to other
populations.
Also, further
studies should be done to replicate the findings and investigate any potential
implications.
Atherosclerosis
Atherosclerosis
occurs when the inner lining of the walls of arteries get covered with plaque that
leads to progressive thickening and hardening of the blood vessels. Plaque
is usually comprised of fats, waste products from cells, cholesterol, calcium, and a
blood-clotting material called fibrin.
Excess plaque
formation in the arteries, impedes blood flow through them and gives rise to
diseases such as angina (chest
pain), coronary
heart disease, carotid artery disease, peripheral
artery disease, and chronic
kidney disease.
The current Rotterdam study findings indicate that thyroid
hormone measurement can help identify individuals at risk for atherosclerosis;
this may have future implications for the prevention of atherosclerotic
morbidity and mortality.
"
Future studies should clarify the exact
mechanisms that can explain the link between thyroid function and
atherosclerosis. This could help to identify potential targets for future
preventative strategies," Bano said.
References :- People with higher thyroid hormone levels may be at greater risk for atherosclerosis - (https://www.endocrine.org/news-room/current-press-releases/people-with-higher-thyroid-hormone-levels-may-be-at-greater-risk-for-atherosclerosis)
- What Is Atherosclerosis? - (https://www.nhlbi.nih.gov/health/health-topics/topics/atherosclerosis/)
Source: Medindia
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