Thyroxine and Triiodothyronine Content in Commercially Available Thyroid Health Supplements

Abstract

The majority of dietary thyroid supplements studied contained clinically relevant amounts of T4 and T3, some of which exceeded common treatment doses for hypothyroidism. These amounts of thyroid hormone, found in easily accessible dietary supplements, potentially expose patients to the risk of alterations in thyroid levels even to the point of developing iatrogenic thyrotoxicosis. The current study results emphasize the importance of patient and provider education regarding the use of dietary supplements and highlight the need for greater regulation of these products, which hold potential danger to public health.

Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement

“…Nonetheless, as noted in the AACE guidelines "No published data, however, support the claim that ingestion of tyrosine increases the production of thyroid hormone (patient advised to discontinue use)." Commercially available supplements sold for "thyroid health" or "thyroid support" may also contain measurable amounts of T4 and T3, potentially exposing the public to iatrogenic thyrotoxicosis (571).…”

A ‘Natural’ thyroid storm!

“…Under the Dietary Supplement Health and Education Act, such ‘natural’ supplements are largely unregulated and not subject to the same Good Manufacturing Practices or quality control measures required of drugs in the market today. For this reason, thyroid extracts in today's market have once again been found to have disparaging inconsistencies in composition, delivering anywhere from non‐existent to supratherapeutic doses of T3 and T4 …”

There is no ‘universal fit’: Reflections on the use of l-triiodothyronine in the treatment of hypothyroidism

“…While there is one short-duration study indicating that some patients prefer thyroid extracts treatment, long-term randomized controlled trials (RCTs) are lacking [2]. Indeed, the high amounts of T4 and T3 detected in 10 commercially available thyroid dietary supplements could be sufficient to expose patients to the risk of developing iatrogenic thyrotoxicosis [8]. Indeed, the high amounts of T4 and T3 detected in 10 commercially available thyroid dietary supplements could be sufficient to expose patients to the risk of developing iatrogenic thyrotoxicosis [8].…”