A recent announcement by the Food and Drug Administration about natural thyroid treatment has readers of this newspaper column up in arms. Nearly 5% of American adults have a thyroid gland that doesn’t function well (hypothyroidism).

The treatment supplies thyroid hormone that their glands don’t make. This may be in the form of synthetic levothyroxine, such as Synthroid, or it could be an extract of an animal thyroid gland, such as Armour Thyroid.

One reader expressed her distress with the FDA’s plan: “I have learned from one of my doctors that the FDA has made a ruling to ban Armour Thyroid medications.

They will require everyone who needs thyroid medication to use synthetic levothyroxine.

“I have taken both levothyroxine and Armour thyroid. I did not do well on levothyroxine, but I have done quite well on Armour. For the million or more patients in the U.S. who need Armour, how can we continue to get this drug?

“The FDA report says that there have been a few adverse reactions to natural pig thyroid. They claim the production is not well controlled.

“I read a report that one of the companies that manufactures levothyroxine in India has failed repeated FDA inspections but is still allowed to send the product to the USA. How is that better? I hope we can protect ourselves from shoddy manufactured products and maintain access to the natural product that works for us. Do you know how we should proceed?

“Right now, I take 30 milligrams Armour Thyroid and my TSH, T3 and T4 levels are just where they should be. I don’t want to mess with my thyroid by changing medicines. I am terrified of going back to levothyroxine.”

This reader is not alone in her preference for Armour Thyroid, also described as desiccated thyroid extract (DTE). The manufacturer of this natural product is no fly-by-night drug company. It is Allergan, a subsidiary of AbbVie, a giant pharmaceutical firm. AbbVie also makes the brand name levothyroxine product, Synthroid.

We find the FDA’s plan to phase out DTE shortsighted. Some patients do not do well on levothyroxine alone. Doctors have assumed that levothyroxine (T4) is adequate because research in 1970 revealed an enzyme converting T4 (which is inactive) to the active compound T3 (also called liothyronine).

Even though most people can manage this conversion, millions have a different genetic makeup that is less efficient (Current Opinion in Endocrinology, Diabetes and Obesity, October 2018).

These folks do not do well on levothyroxine alone. Not only do they feel worse, but they are also at higher risk for Alzheimer’s disease.

The scientist at the forefront of this research is Dr. Antonio Bianco of the University of Texas Medical Branch in Galveston. He has studied the use of liothyronine in combination with levothyroxine to treat hypothyroidism (Thyroid, October 2020). Studies demonstrate that combination therapy is helpful without undue risks for the 15% of hypothyroid patients who don’t respond adequately to levothyroxine (Journal of Clinical Endocrinology and Metabolism, Sept. 1, 2020).

If you would like to learn more about this approach, you may wish to listen to our interview with Dr. Bianco. It is “Show 1330: Rethinking Hypothyroidism,” available at www.PeoplesPharmacy.com.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 300 W. 57th Street, 41st Floor, New York, NY 10019, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”