Under-active thyroid can increase heart failure risk

According to a new study older adults people who have an under active thyroid, or hypothyroidism, but with no symptoms, have an increased the risk of congestive heart failure.

Apparently asymptomatic hypothyroidism is causes an increase in the level of the thyroid stimulating hormone (TSH), but a normal level of thyroxine (T4).

It seems the prevalence of the condition increases with age.

Dr. Nicolas Rodondi from the University of Lausanne, Switzerland and colleagues explain that asymptomatic hypothyroidism has been associated with higher levels of some cardiac risk factors but data on cardiovascular outcomes and death have been limited.

In a 4-year study, Rodondi and his team examined the risks of heart failure, coronary heart disease, stroke, peripheral artery disease and death compared with TSH levels in 2,730 men and women between 70 and 79 years old.

They found that hypothyroidism was detected in 338 (12.4 percent) of study the group, and compared with adults with normal thyroid function, congestive heart failure was about twice as common in patients with moderate or severe asymptomatic hypothyroidism.

The condition was not associated with an increased risk of coronary heart disease, stroke, peripheral arterial disease, or cardiovascular and total mortality.

Rodondi says however that the results need to be confirmed by other large studies and in younger patient populations, and it remains unclear whether symptomatic hypothyroidism causes or worsens heart failure that already exists.

Rodondi says whether screening and treatment of asymptomatic hypothyroidism is advisable is controversial because the current evidence is limited by the small number of large studies that have been conducted.

In a related editorial, Dr. Lawrence M. Crapo of Santa Clara Valley Medical Center in San Jose, California, says that the study supports the idea that treating severe cases of asymptomatic hypothyroidism with levothyroxine in patients younger than 80 years may be helpful, but this need to be confirmed in a therapeutic trial.

The study is published in the Archives of Internal Medicine, November 28, 2005.

News-Medical.Net Staff