Randy’s words from a website about Armour porcine thyroid: I, too, was doing great on Armour. No more. They put me on levothyroxine [synthetic T4] and Cytomel [synthetic T3]. I felt awful, so depressed...

Drugmakers fake and suppress their studies. Knoll Pharmaceuticals, the Synthroid maker, hid one showing that their drug was no better than the other thyroids. Knoll paid more than $100 million to consumers after the ensuing class-action lawsuit settled in 2000. 

Later, the pharmaceutical companies sponsored over ten bogus studies that purported to show porcine thyroid was no improvement over T4. Each trial used only 1/2 grain of the pork thyroid (30 mg), even though the proper dose is one to two grains (60-120 mg) or more (about the same as .075 to .15 mg of T4). Each study concluded that the tiny dose of pig thyroid did not work. With these doses, of course, it could never work. This type of false comparison is a routine strategy used by drugmakers to get FDA approval or to run down a competitor. For more, see Ben Goldacre’s Bad Pharma (2012) and my FDA chapter here.

There have been claims that the porcine thyroid manufacturing is faulty, and that this makes it inferior to Synthroid, the branded T4. However, Synthroid was recalled ten times between 1991 and 1997. This involved over 100 million tablets. The FDA requires T4 to fall within 5% of its stated potency, but most samples analyzed had far less active ingredient and some had none. Because many patients need thyroid to survive, there were hospitalizations. 

In 2001, the Food and Drug Administration (FDA) issued a warning that they might pull Synthroid from the market. There were also two recalls in 2012-13 involving issues with potency, stability, and manufacturing. See Mary Shomon’s website for references, including the FDA letter documenting the story. This link is offline and may have been suppressed by special interests. I had to search for it on the Wayback Machine internet archive (archive.org). 

Physicians have used porcine thyroid for over a century. It was first approved by the FDA in 1939. In Thailand, it is an over-the-counter supplement. I could find only three recalls for this desiccated pig thyroid, including one started by the manufacturer in 2020 for a 13 percent drop in potency. This might have gone unnoticed, but since thyroid strength is critical, they were doing the right thing.

T4 has been available since 1927 without a formal FDA evaluation. It was given “grandfather” status in 1938 because it was assumed to be equivalent to porcine thyroid, which was considered the “gold standard.” The Synthroid brand finally passed a perfunctory FDA review in

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