Thyroid UK
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Over-the-Counter Thyroid Supplements

Do over-the-counter thyroid supplements based on animal thyroid glands contain thyroid hormones?

The waters are very murky.

How do you assess this when the manufacturers/distributors often claim they are hormone-free?

Are these products consistent - as in always containing pretty much the same amount of thyroid hormone, whether that is zero or higher?

DICP. 1990 Jan;24(1):26-7.

Therapeutic potential of two over-the-counter thyroid hormone preparations.

Csako GA1, Cetnarowski-Cropp AB, Pucino F.

Author information

1 Department of Clinical Pathology, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892.


Various brands of over-the counter (OTC) exogenous thyroid hormones are available in health food stores and retail pharmacies. Two commercially available OTC thyroid products were analyzed for total thyroxine (T4) and triiodothyronine (T3) content. The strength of a liquid thyroid gland extract was unlabeled and that of the solid oral preparation was 45 mg per table. The T4 concentration of the liquid preparation was less than 10 micrograms/dL; that of T3 was below the analytical sensitivity of our assay (less than 15 ng/dL). Tablet content of T4 and of T3 was up to 0.5 micrograms and up to 50 ng, respectively. Preliminary data on these OTC thyroid gland extracts cannot be extrapolated to all OTC thyroid products, but they suggest that such products generally contain concentrations of T4 and T3 below clinical effectiveness. Further analytical study is warranted.

PMID: 2301185

Ann Pharmacother. 1992 Apr;26(4):492-4.

Evaluation of two over-the-counter natural thyroid hormone preparations in human volunteers.

Csako G1, Corso DM, Kestner J, Bokser AD, Kennedy PE, Pucino F.

Author information

1 Clinical Pathology Department, National Institutes of Health, Bethesda, MD 20892.



To determine the pharmacologic activity of over-the-counter (OTC) thyroid preparations.


In vitro analysis and a prospective, crossover study in vivo.


Tertiary care center.


Two healthy adult volunteers.


Three OTC preparations (Thyrotrophin PMG [bovine thyroid PMG extract], Thyro Forte [thyroid lymphogland concentrate with synergistic complex], and Thyro Complex [thyroid lyophilized gland concentrate with synergistic complex]) were analyzed in vitro. Volunteers were administered two times the manufacturer's maximum recommended daily dose of either Thyrotrophin PMG or Thyro Forte for one week, washed out for four to five weeks, and crossed over to receive the opposite tablet preparation for an additional week.


The triiodothyronine (T3) and thyroxine (T4) contents of OTC preparations were measured by HPLC. Vital signs, serum total and free T4, total T3, thyroid stimulating hormone, thyroxine binding globulin, thyroglobulin, and general chemistry tests (including glucose and cholesterol) were monitored before, during, and between administration of the products.


HPLC analysis of the three OTC preparations showed no T4 but did show possible T3 in two of these products. We found no definite clinical or laboratory evidence of thyroid hormone excess with either product.


Healthcare professionals should advise against the use of these scientifically unsound and relatively expensive OTC thyroid preparations, of which the therapeutic efficacy is unknown.

PMID: 1576386

DOI: 10.1177/106002809202600408

Thyroid. 2016 Apr;26(4):489-98. doi: 10.1089/thy.2015.0373.

THYROSIM App for Education and Research Predicts Potential Health Risks of Over-the-Counter Thyroid Supplements.

Han SX1, Eisenberg M2, Larsen PR3, DiStefano J 3rd1.

Author information

1 Biocybernetics Laboratory, Departments of Computer Science and Medicine, UCLA , Los Angeles, California.

2 Departments of Epidemiology and Mathematics, School of Public Health, University of Michigan , Ann Arbor, Michigan.

3 Brigham and Women's Hospital/Harvard Medical School , Department of Medicine, Boston, Massachusetts.



Computer simulation tools for education and research are making increasingly effective use of the Internet and personal devices. To facilitate these activities in endocrinology and metabolism, a mechanistically based simulator of human thyroid hormone and thyrotropin (TSH) regulation dynamics was developed and further validated, and it was implemented as a facile and freely accessible web-based and personal device application: the THYROSIM app. This study elucidates and demonstrates its utility in a research context by exploring key physiological effects of over-the-counter thyroid supplements.


THYROSIM has a simple and intuitive user interface for teaching and conducting simulated "what-if" experiments. User-selectable "experimental" test-input dosages (oral, intravenous pulses, intravenous infusions) are represented by animated graphical icons integrated with a cartoon of the hypothalamic-pituitary-thyroid axis. Simulations of familiar triiodothyronine (T3), thyroxine (T4), and TSH temporal dynamic responses to these exogenous stimuli are reported graphically, along with normal ranges on the same single interface page; and multiple sets of simulated experimental results are superimposable to facilitate comparative analyses.


This study shows that THYROSIM accurately reproduces a wide range of published clinical study data reporting hormonal kinetic responses to large and small oral hormone challenges. Simulation examples of partial thyroidectomies and malabsorption illustrate typical usage by optionally changing thyroid gland secretion and/or gut absorption rates--expressed as percentages of normal--as well as additions of oral hormone dosing, all directly on the interface, and visualizing the kinetic responses to these challenges. Classroom and patient education usage--with public health implications--is illustrated by predictive simulated responses to nonprescription thyroid health supplements analyzed previously for T3 and T4 content. Notably, it was found that T3 in supplements has potentially more serious pathophysiological effects than does T4--concomitant with low-normal TSH levels. Some preparations contain enough T3 to generate thyrotoxic conditions, with supernormal serum T3-spiking and subnormal serum T4 and TSH levels and, in some cases, with normal or low-normal range TSH levels due to thyroidal axis negative feedback. These results suggest that appropriate regulation of these products is needed.

PMID: 26895744

DOI: 10.1089/thy.2015.0373

2 Replies

I definitely wouldn't take these preparations.


Thank You. I live in Guatemala City. My TSH levels appear normal as well as my Free T4. However, I am waiting to get my Free T3 levels tested> I still have not been diagnosed with Hypothyroidism yet. I have severe depression, trouble concentrating, poor memory, brain fog, severe constipation among others. I have been a Type 1 Diabetic for 27 years.

It is highly likely that I have a problem converting T4 to T3.

Here in Guatemala, only Synthroid is available. Here in Guatemala, Cytomel or Cynomel are not available. Neither are any dessicated thyroid products on sale. My Endo mentioned a product sold here from Vitamin Shoppe that has Iodine, Selenium, and many other minerals and Vitamins as well as small amounts of dessicated thyroids, kidneys from Pigs. If the tests results show that I have low Free T#, then I will have to try this product.

Thanks for the referrals to the articles.


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