A great question came from a member who was taking Synthroid for hypothyroidism: “Should I be concerned I’m still having symptoms while on Synthroid? Should I switch to Armour thyroid? Why are some doctors hesitant to prescribe Armour Thyroid?
Armour Thyroid, or desiccated thyroid, is a variable mixture of T3 and T4 made from the thyroids of pigs. Many patients like the idea of a more “natural” thyroid replacement over using synthetic thyroid hormone like Synthroid (Levothyroxine) but is there any reason to switch to Armour?
One of the problems with Armour, which is why some Physicians are leery of prescribing it, is that the amount of T4 and T3, and the bioavailability of Armour thyroid can vary across batches. In general, 1 grain of Armour is equivalent to a total of about 74 mcg T4 but this can vary quite a bit.
Another problem with T3/T4 combinations like Armour is that patients treated with T3-containing preparations have wide fluctuations in serum T3 concentrations throughout the day due to its rapid gastrointestinal absorption and its relatively short half-life in the circulation…which is about 1 day.
Does taking combination T3/T4 (Armour) result in more symptom relief than synthetic thyroid hormone? No question about it. I have patients who report a difference but the studies don’t support this. In most large studies, combination T3/T4 therapy (Armour) does not appear to be superior to T4 monotherapy (Synthroid which is Levothyroxine) for the management of hypothyroid symptoms. A small study done on thyroidectomized patients did show that some derived benefit from Armour but in patients with Autoimmune Thyroiditis (Hashimotos Thyroiditis) studies have not shown any benefit.
The reason you can’t find Armour thyroid in most pharmacies now is that only three drug companies make it in the U.S. and all have slowed production. The reason for this is believed to be the Swine Flu scare and the fear of using pig thyroid for Armour.