When older folks go to the doctor saying they’re tired or having trouble losing weight, a common response is to test the thyroid gland.

The gland produces hormones that have many regulatory effects on the body — fatigue, weight gain, feeling cold, dry skin, constipation and more.

So, if tests indicate the thyroid is slowing down, doctors often turn to a synthetic thyroid hormone called levothyroxine, or Synthroid.

But that might be ineffective, according to a new study published in the New England Journal of Medicine.

In the study, researchers conducted a randomized trial of people over age 65 who had what’s called subclinical hypothyroidism.

People with subclinical hypothyroidism essentially have mild symptoms of hypothyroidism, or fatigue, depression or feeling cold.

They were treated with levothyroxine, which researchers found to have no apparent benefit.

“This really raises the question of, should we be doing this?” said MPR News medical commentator Dr. Jon Hallberg. “And I’ll tell you, a lot of us in primary care are prescribing this kind of thyroid hormone.”

One danger of overprescribing this medication is that it can create an opposite problem: hyperthyroidism.

What’s behind these symptoms then?

“At the end of the day, a lot of times we are just tired, and we just can’t explain it,” Hallberg said.

He joined All Things Considered host Tom Crann to discuss thyroids, the study and what it all means.