The symptoms of hypothyroidism are well known: Weight gain, brain fog, thinning hair and feeling cold. The prescription (levothyroxine) is also standard.. But a third presumption - that hypothyroidism treatment reverses weight gain - has just been blown out of the water in a new study, reported Medscape on October 21.
"We found that modest weight loss following initiation of levothyroxine treatment for hypothyroidism occurs in only about half of patients," said Elizabeth Pearce, MD, from endocrinology, diabetes, and nutrition section of Boston University School of Medicine, Massachusetts.
Michael T. McDermott, MD, director of endocrinology and diabetes practice at the University of Colorado School of Medicine, Aurora, admitted that he was surprised by the findings.
"I would expect weight loss to occur but would expect [it] to be much more significant in people with more severe hypothyroidism and less, if any . . . in those with mild or very mild hypothyroidism, which most of the subjects in the current study had," he commented.
However, Dr. Pearce noted that despite the expectations of most physicians and patients that weight loss will occur following treatment, very few studies actually have analyzed weight changes in patients who had been treated.
For the study, scientists analyzed the electronic medical records of 101 patients. More than 70 percent were women, and the average age was around 50. All were newly diagnosed with primary hypothyroidism.
The surprising results: Although the patients improved based on their laboratory tests, the impact on their weight was insignificant. Only about half of the patients lost weight, and they lost about eight pounds on average.
So is the message that expensive laboratory tests and medication for hypothyroidism aren't worth it? No, emphasizes Dr. Pearce.
"Although we did not have a control group for comparison in this study, in general, in adult populations, weight gradually increases over time," she noted. Therefore, if those individuals had not undergone thyroid treatment, they might have gained weight rather than lost or stayed steady.
Adding to the difficulty in quantifying the benefits of hypothyroid treatment: "There is no research demonstrating how much weight patients gain with the onset of hypothyroidism; this would be hard to do, as it is usually impossible to determine exactly when hypothyroidism first developed," Dr. Pearce added.