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Armour Thyroid & Potency Print E-mail


It’s well known that some of the “natural” thyroid products are in short supply. Armour Thyroid (by Forrest Labs) is a particular problem. In response, compounders have been making substitutes with the main ingredient in Armour Thyroid, which is Thyroid, USP, Porcine.

This should work. However, we are hearing reports that equivalent doses of Thyroid, USP, Porcine are not giving equivalent responses. People are finding that it takes more Thyroid, USP, Porcine to accomplish the same therapeutic effect.

Why? I have no specific proof of the following explanation. It began as a rumor, but it is very likely to bear some truth. It seems that thyroid glands today are not as “potent” as they were a few decades ago. The reasons are many, but the result is that each gram of desiccated thyroid is less potent than it had been. The manufacturers have reportedly been adding T3 and T4 (two important thyroid hormones) to the “natural” thyroid products. They did this for the best intentions, to assure that today’s thyroid product was as effective as the ones in the past.

A difficulty arises in that adding material to a product that is already FDA approved is considered adulteration – even if the added substance is a benefit. FDA approved drugs may not be adjusted without FDA approval. If the FDA has not approved the adulteration with additional T3 and T4, they could have a case against the manufacturers.

Is this important? People report that they feel fine when they use more of a compounded version of Thyroid, USP, Porcine. For example, a person using 1 grain of Armour Thyroid reports that the compounded version helps when he takes 3 or 4 grains. It must be remembered that when switching back to Armour Thyroid (when possible), the doctor must assure that the appropriate dose is used – 1 grain, not the 3 to 4 grains that seem to work when using Thyroid, USP, Porcine.

There is one method to help a person get the thyroid he or she needs without setting up a situation that may be dangerous if (when) the commercial product returns. Use a compounded blend of T3 and T4 that has been designed to exactly meet the patient’s needs. Ask your compounding pharmacist to help design the dosage. We have charts that describe the equivalent amounts of T3 and T4 that are reportedly in the specific sizes of Armour Thyroid. For example, 1 grain of Armour Thyroid delivers approximately 38 mcg of T4 and 9 mcg of T3 (a ratio of about 4 to 1). It is important to use the correct units of measure. Mcg refers to microgram, which is one one-thousandths of a milligram. Accidentally ordering gm of T3 or T4 would result in a one thousand times overdose. It could be fatal.

T3 = Liothyronine

T4 = Levothyroxine

T3/T4 Equivalency table



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