Levothyroxine as monotherapy should remain the standard of care for the treatment of hypothyroidism, despite the common combination of the drug with alternative agents to tackle tough cases of the condition, according to new treatment guidelines set forth by the American Thyroid Association (ATA).
"All in all, our guidelines offer reassurance to physicians and their patients [that] no changes are needed in the current standard of care for hypothyroidism in the majority of patients," said Jacqueline Jonklaas, MD, PhD, chair of the task force looking into the issue and an associate professor at Georgetown University Medical Center, in Washington, DC, in a press statement.
Levothyroxine, sold as Synthroid (AbbVie) and other trade names as well as generics, is well established as the gold standard of treatment for hypothyroidism; however, alternative therapies have emerged for the relatively few patients — about 15% — who don't respond well to the drug, necessitating this updated look at treatment strategies, Dr. Jonklaas told Medscape Medical News.
"More studies have been conducted on combination therapy with [the thyroid hormone triiodothyronine] T3 in recent years, and so the American Thyroid Association thought it would be wise to rereview the evidence," she said.
Time to Rereview the Evidence
Levothyroxine is a synthetic form of the hormone T4 that is converted to T3 inside the body. Dr. Jonklaas and the expert task force explain in their paper, published online September 29 in Thyroid, that some patients feel unwell while taking levothyroxine monotherapy.
While the number of such patients does not appear to be increasing, "it does concern physicians that there are any patients at all who do not feel returned to full health," she explained.
The task force was therefore convened to review the goals of levothyroxine therapy, the optimal prescription of conventional levothyroxine therapy, the sources of dissatisfaction with this therapy, the evidence on treatment alternatives, and the relevant knowledge gaps.
"We wished to determine whether there are sufficient new data generated by well-designed studies to provide reason to pursue such therapies and change the current standard of care," they explain in the paper.
They conducted an extensive literature review of 3 commonly used therapeutic categories: levothyroxine monotherapy; non–levothyroxine-based thyroid-hormone therapies including nutraceuticals, thyroid extracts, synthetic combination therapy, triiodothyronine therapy, and compounded thyroid hormones; and the use of thyroid-hormone analogs.
The challenges of titrating thyroid-hormone therapy in specific groups such as the pediatric, pregnant, and elderly populations are also discussed, but the topic of subclinical hypothyroidism is not addressed, other than in the pediatric population, "because of prior extensive reviews of this topic in adults," say the task force.
They found that, overall, the evidence was insufficient to justify a change in the treatment guidelines.
"The studies were performed in many different ways [and] had some inconsistent findings, and none looked at use of a T3 agent for an extended period, which is necessary to uncover side effects," Dr. Jonklaas explained.
While some studies suggested combination therapy could be a valid approach, the expert panel concluded there was not yet robust evidence to recommend this. "More studies need to be done before we could really be sure of this result," Dr. Jonklaas urged.
Nevertheless, she said the door is left open for certain patients who may indeed benefit from combination therapies for hypothyroidism.
"It is possible that patients with a certain genetic makeup — a polymorphism or genetic variation in the deiodinase enzyme that converts levothyroxine (T4 to T3) — may specifically benefit from combination therapy," she noted.
"We should…conduct studies that specifically examine treatment in the individuals who have the genetic characteristic that was identified in the preliminary studies," she said.
Essential Guidance for Endocrinologists
"Despite the advances that have occurred in the field of therapy for hypothyroidism, there are still many unanswered questions," the task force concludes.
Nevertheless, the new guidelines will provide essential guidance to clinicians, Hossein Gharib, MD, president of the ATA, professor of medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, said in a press statement .
"These ATA guidelines, developed by an expert team, provide useful, up-to-date information on why to treat, who to treat, and how to treat hypothyroidism.
"Information is evidence-based and recommendations are graded. I think they will be used extensively by all clinical endocrinologists, especially by our members," he concluded.
Dr. Jonklaas reports that she and a coinvestigator, Kenneth D Burman, MD, director of the endocrine section at MedStar Washington Hospital Center in Washington, DC, have conducted a study of a T3 product funded by IPE; however the study was designed only to look at blood levels of T3, and the product was not discussed in the guidelines. The other coauthors have reported no relevant financial relationships.
Thyroid. Published online September 29, 2014. Article
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Cite this: New ATA Guidelines Stick With Levothyroxine for Hypothyroidism - Medscape - Oct 02, 2014.