Metformin, a commonly used drug for type-2 diabetes, has been found to increase the risk of low thyroid-stimulating hormone (TSH) levels in patients with underactive thyroids (Hypothyroidism), according to a McGill University study.
The researchers said that low levels of TSH can affect cardiovascular conditions and fractures.
Metformin lowers blood glucose levels by decreasing glucose production in the liver. Previous studies concluded that metformin may upset thyroid-stimulating hormone levels.
For the study, the researchers examined data on 74,300 patients who consumed metformin and sulfonylurea, another common diabetes drug, for over a period of 25 years. Out of these pateints, 5689 were identified with hypothyroidism and 59,937 were associated with normal thyroid function. In the hypothyroidism group, 495 patients reported low thyroid-stimulating hormone (119.7 per 1000) per year as compared to 322 in the normal group (4.5 per 1000).
The researchers found that in the hypothyroidism group, metformin monotherapy increased TSH risk by 55 percent as compared to the treatment with sulfonylurea.
"The results of this longitudinal study confirmed that the use of metformin was associated with an increased risk of low TSH levels in patients with treated hypothyroidism," said Dr. Laurent Azoulay, Lady Davis Institute, Jewish General Hospital and the Department of Oncology, in a press release. "Given the relatively high incidence of low TSH levels in patients taking metformin, it is imperative that future studies assess the clinical consequences of this effect."
The finding is published in the Canadian Medical Association Journal.
According to a recent study by the University of Copenhagen, Denmark, hyperthyroidism patients are more likely to avail sick leave for extended periods than their healthy counterparts. This was particularly true at least in the first year after diagnosis.
Hyperthyroidism is a medical condition that occurs when the thyroid gland becomes overactive, meaning, too much of thyroid hormone production. The most common cause of hyperthyroidism is Graves' disease, where the immune system generates antibodies that attack the thyroid gland. The disease is soon followed by eye complications or inflammation of the thyroid gland known as a goiter.
"When we examined sick leave records, our research found patients with hyperthyroidism faced a significantly higher risk of missing work for three weeks or longer due to illness compared to healthy controls," said one of the study authors Mette Andersen Nexø of the National Research Centre for the Working Environment, in a press release.
"People who experienced eye complications from Graves' disease were the most likely to require extended sick leave. This same population also was the most likely to leave the workforce altogether and retire on a disability pension."
