Thyroid hormones tend to have a direct effect on the bone metabolism as well as increased thyroid function that could result in the bones having increased metabolic impact. In the study, the researchers found that even having a thyroid gland that is mildly overactive could result in an increased risk of fractures, particularly in the spinal area or around the hips. The condition of ‘subclinical hyperthyroidism’ involves the overactive thyroid gland producing a lot of hormones, which keeps the basic metabolism controlled even though there are no symptoms with the hormone readings being normal in the blood tests.

In researches conducted in the past, cases of hyperthyroidism that are more pronounced are usually linked to a high risk of fracture as explained by the reviewers. However, there hasn’t been information on whether the same also applies to forms of this condition that are milder. When carrying out the recent study, the Swiss reviewers analyzed 13 past studies that involved over 70000 patients in their efforts of getting answers to this question. Several studies in the past have suggested a high risk of fractures but whether the association was real hasn’t been clear until now.

Why the risk is high?

The researchers said that based on the work they had done, they are now sure that the patients usually have a high risk of getting a fracture. Why this is the case is not yet clear. However, what is well kwon is that bone metabolism is affected by thyroid hormones and an increase in the thyroid function could have a high metabolic effect on the bones. As such, accelerated bone turnover is one of the explanations, which results in re-modeling and destruction of the bones. Among the subjects of the study, about 3 percent of them had subclinical hyperthyroidism and about 6 percent of them had hypothyroidism, which is an opposite problem to the condition.

Fracture risk and mild hyperthyroidism

The review team ultimately didn’t find any association between increased risks of fracture being caused by an underactive thyroid. However, those with a thyroid that is symptomless but overactive didn’t seem to have an increased risk of bone breakage in the spinal regions and hips. Regardless of gender or age, the finding did hold up even though the researchers said that no enough data was available for them to give a comment on the way the equation might be affected by race. Even though this study managed to show that an association existed between fracture risk and mild hyperthyroidism, there was no proof that the fractures are caused by the condition.

The team doing the research didn’t recommend that changes be done on the treatment guidelines available currently for hyperthyroidism. One of the reasons given for this is that it isn’t clear whether subclinical hyperthyroidism treatment could help in reduction of the fracture risk.