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Thyroxine ‘reduces CVD risk by 40%’ in under 70s

Treating subclinical hypothyroidism dramatically reduces the risk of CVD in the under-70s, but may increase the risk of events in older patients say UK researchers.

Their study looked at data from the GP records of 4,735 patients with serum thyroid stimulating hormone levels of 5.01 to 10 mIU/l for over nearly eight years and evaluated the effect of synthetic thyroid hormone treatment.

They found those aged 40-70 years treated with levothyroxine had a 37% decrease in risk of ischaemic heart disease than those who were not. But this effect was attenuated in those aged over 70, with a 6% increase in risk, compared with those not taking levothyroxine.

When analysed by median baseline serum TSH levels, the younger group with levels below 6.6 miu/l experienced a 38% reduction in risk of ischaemic heart disease events, compared with the control group. By comparison, the older sub-cohort experienced a 25% increase in risk.

Study lead Dr Salman Razvi, consultant endocrinologist and honorary senior clinical lecturer at Queen Elizabeth Hospital in Gateshead, said: ‘It remains possible that the benefits of treatment of subclinical hypothyroidism in older persons may be offset by an increased risk of levothyroxine-precipitating adverse cardiovascular events.'

Arch Intern Med 2012, online 23 April 2012