Natural Desiccated Thyroid Drugs as Alternatives to Levothyroxine

Thyroid gland

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Natural desiccated thyroid—known as NDT, thyroid extract, and porcine thyroid—is a prescription thyroid medication that is derived from the dried thyroid gland of pigs.

Natural desiccated thyroid was the first manufactured drug used to treat hypothyroidism and has been available for more than a century.

The Shift to Levothyroxine

For the first half of the twentieth century, natural desiccated thyroid—namely, the brand known as Armour Thyroid—was the only treatment available for hypothyroidism. In the 1950s, a synthetic form of thyroxine (T4) was developed. Thyroxine is one of the two key hormones the thyroid gland produces. This synthetic thyroxine was known as levothyroxine, or l-thyroxine, and was promoted as a more modern treatment option for hypothyroidism, compared to natural desiccated thyroid.

Unlike levothyroxine, which is a synthesized version of the T4 hormone, natural desiccated thyroid contains two key thyroid hormones—T4 (thyroxine) and T3 (triiodothyronine)—as well as calcitonin, and other elements found in an organic thyroid gland. A normal thyroid gland produces primarily T4 (the storage hormone) and some T3, and the T4 is converted into T3, the active hormone, for use by the cells and tissues of the body.

Levothyroxine has been the preferred treatment of the conventional medical world since its introduction. (Some of the commonly known brands of levothyroxine include Synthroid, Tirosint, Unithroid, and Levoxyl). Natural desiccated thyroid drugs, including brand names Nature-Throid, Thyroid WP, Armour Thyroid, and Acella's generic natural thyroid drug NP Thyroid, have remained on the market. These drugs continue to draw criticism and fire from conventional physicians and competing drug companies, who label it as "old-fashioned" and outdated. Meanwhile, a subset of thyroid patients has continued to prefer natural desiccated thyroid over levothyroxine, likely due to the presence of both T4 and T3 hormones in the natural desiccated thyroid, versus just T4 in levothyroxine.

Natural Desiccated Thyroid Versus Levothyroxine

The issue of natural desiccated thyroid, versus levothyroxine, has been controversial for decades. Despite half a century of use, after the introduction of levothyroxine, physicians frequently argued against the use of natural thyroid drugs, stating that there weren't studies showing it to be safe or effective. 

For fans of natural desiccated thyroid, there was important news for thyroid patients that came out of the Endocrine Society Annual Meeting, which took place June of 2013 in San Francisco. According to a presentation made by Thanh D. Hoang, DO, staff endocrinologist of the Walter Reed National Military Medical Center in Bethesda, MD, natural desiccated thyroid drugs are viable alternatives to thyroid hormone replacement treatment with levothyroxine.

For this study, Dr. Hoang conducted a randomized, double-blind, crossover study to compare the effectiveness of natural desiccated thyroid versus levothyroxine as a hypothyroidism treatment. The study evaluated a total of 70 patients, who ranged from the age of 18 to 65, and all had primary hypothyroidism. The patients were randomly assigned to a group that took either a natural desiccated thyroid drug or levothyroxine, for a total of 16 weeks. The studies were blind, meaning that patients did not know which of the two medications they were receiving.

At the end of the study, the patients were asked which drug regimen they preferred. Interestingly, almost half the group—specifically, 49 percent—referred the natural desiccated thyroid treatment, compared to almost 19 percent who preferred levothyroxine. About 33 percent of the patients didn't specify a preference.

Of particular interest: Dr. Hoang also reported that the patients taking natural desiccated thyroid lost approximately three pounds during the study period, compared to the patients taking levothyroxine, who did not lose any weight.

Dr. Hoang told Endocrine Today: "We didn't find any differences in the neurocognitive measurements between the two therapies...We now know that once-daily desiccated thyroid extract is a safe alternative treatment for patients with hypothyroidism who are not satisfied with levothyroxine treatment. It's an option for them to try, and also desiccated can cause modest weight loss in these patients as well."

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Article Sources
  • Hoang TD, et al. "Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double-blind, crossover study." J Clin Endocrinol Metab. 2013 May;98(5):1982-90. doi: 10.1210/jc.2012-4107. Epub 2013 Mar 28.