Elderly patients on hypothyroid therapy may face an increased risk of fractures if treatment doses are not monitored and adjusted, researchers have said.
Dr Marci Turner and colleagues from the University of Toronto in Canada studied data on 213,511 patients receiving levothyroxine treatment. These patients were matched with 100,660 controls. The researchers found that among adults aged 70 or over, current levothyroxine treatment was associated with an 88 per cent increased risk of fracture.
High and medium cumulative doses were associated with a significantly increased risk of fracture compared with low cumulative doses.
Older people often require smaller doses of thyroid therapy to achieve normal function and therefore may have been overtreated, which could increase fracture risk.
The researchers said the findings showed the importance of ongoing monitoring of thyroid dysfunction.
Writing in the BMJ, the researchers said: 'Our study shows that levothyroxine treatment is associated with a higher risk of fractures in a dose-response manner in older adults, and that dosages commonly used in clinical practice, especially over 0.093 mg a day, may be excessive for this population.
'Our study raises concerns that levothyroxine treatment targets may need to be modified in elderly people and that dose monitoring remains essential even into older age.'
In an accompanying editorial, Professor Graham Leese of Ninewells Hospital and Medical School in Dundee said current evidence suggested elderly people needed relatively low levothyroxine doses.
'Serum thyroid-stimulating hormone concentrations should be regularly monitored and a suppressed thyroid-stimulating hormone concentration should be avoided in such patients.'