Thyroid problems linked to irregular heart rhythm

People with an overactive thyroid gland (hyperthyroidism) carry a greater risk of developing irregular heart rhythm (known as atrial fibrillation) than those with normal thyroid function, finds a study published on BMJ today.

As such, the researchers suggest there should be an increased focus on atrial fibrillation in patients with raised thyroid function.

occurs when the thyroid gland makes too much (), causing many of the body's functions to speed up. About 1 in 100 women and 1 in 1,000 men develop hyperthyroidism at some stage of their life and it can happen at any age.

It is well known that overt hyperthyroidism is associated with atrial fibrillation, but it's still not clear whether milder (subclinical) hyperthyroidism has a similar effect. Data on the risk of atrial fibrillation in patients with an underactive thyroid (hypothyroidism) is also limited.

So a team of researchers in Denmark set out to examine the risk of atrial fibrillation in relation to the whole spectrum of in a large group of patients.

Using nationwide registries, they identified 586,460 patients who had consulted a general practitioner in Copenhagen from 2000 to 2010 and had a thyroid function blood test. This measures the amount of thyroid-stimulating hormone (TSH) circulating in the blood. In people with hyperthyroidism the level of TSH will usually be low, whereas in people with hypothyroidism the level of TSH will usually be high.

During an average five and a half years follow-up, 17,154 (3%) of patients had a diagnosis of a first atrial fibrillation, 53% of whom were women.

Compared to patients with normal thyroid function, the risk of atrial fibrillation increased with decreasing levels of thyroid-stimulating hormone. For example, patients with subclinical hyperthyroidism had a 30% increased risk of atrial fibrillation, while patients with high-normal had a 12% increased risk.

In contrast, hypothyroidism was associated with a lower risk of atrial fibrillation.

The authors stress that, although atrial fibrillation was closely associated with thyroid activity, they cannot prove a direct cause-and-effect relationship. However, they say their study is "the first to assess the association between the whole spectrum of thyroid disease and the subsequent risk of atrial fibrillation in a population of primary care patients."

They conclude: "These results support long term screening for in patients with thyroid disease."

add to favorites email to friend print save as pdf

Related Stories

Thyroid condition linked to heart problems: study

Apr 25, 2012

(HealthDay) -- New evidence suggests that a type of overactive thyroid condition appears to boost the risk of heart problems, especially atrial fibrillation (a form of irregular heartbeat) and premature death.

Rheumatoid arthritis linked to irregular heart rhythm

Mar 08, 2012

People with rheumatoid arthritis are at a greater risk of irregular heart rhythm (known as atrial fibrillation) and stroke compared with the general population, finds a study published in the British Medical Journal today. ...

Recommended for you

UN implores all countries to help on Ebola

1 hour ago

The international group Doctor Without Borders warned Tuesday that the world is 'losing the battle' against Ebola, while U.N. officials implored all countries to quickly step up their response by contributing health experts ...

Travel restrictions could worsen Ebola crisis: experts

6 hours ago

Travel restrictions could worsen West Africa's Ebola epidemic, limiting medical and food supplies and keeping out much-needed doctors, virologists said Tuesday as the disease continued its deadly spread.

World 'losing battle' to contain Ebola: MSF (Update)

6 hours ago

International medical agency Medecins sans Frontieres said Tuesday the world was "losing the battle" to contain Ebola as the United Nations warned of severe food shortages in the hardest-hit countries.

Mutating Ebola viruses not as scary as evolving ones

7 hours ago

My social media accounts today are cluttered with stories about "mutating" Ebola viruses. The usually excellent ScienceAlert, for example, rather breathlessly informs us "The Ebola virus is mutating faster in humans than in animal hosts ...

War between bacteria and phages benefits humans

8 hours ago

In the battle between our immune systems and cholera bacteria, humans may have an unknown ally in bacteria-killing viruses known as phages. In a new study, researchers from Tufts University, Massachusetts ...

User comments