Doctor's Answer:
While it is reasonable to assume that synthetic medications are less desirable than natural counterparts, in this case- natural thyroid hormone replacement is definitely not an ideal solution for the vast majority of people.
Here's why:
Armour thyroid is derived from desiccated pig (porcine) thyroid gland. A number of years ago, these natural preparations were our only alternative. Replacement with desiccated thyroid creates dosing problems because there is no way to standardize the exact amount of the dose for each batch. As a matter of fact, these preparations do not report their dosage strength in milligrams, but rather, in grains of thyroid. This is because, they don't really know the milligram equivalent in each dose. Dosing is also based on the assumptions that each gland has equal amounts of hormones as the next gland, and that the ratio of T4 and T3 (the more active hormone) are similar and constant in each gland from the pigs. There is no way to be certain of this, and patients on these preparations often have fluctuating hormone levels, which may or may not result in symptoms.
Regardless of symptoms, the goal of replacement therapy is to keep the hormone levels as stable as possible. This is much easier to achieve with synthetic preparations such as Levoxyl and Synthroid. These preparations come in a vast number of standardized doses, allowing for minute adjustments in hormone dosing. There is another comment that should be made. With all the issues surrounding "mad cow disease" and other ailments, I personally am reluctant to offer animal based therapy to patients when a safe effective well studied synthetic preparation is widely available.
I hope this helps answer any questions you may have. Thank you for your question.
Medical Author: RM, M.D.
"Natural Thyroid is Not an Ideal Solution" ? !!!!
This nonsense really makes my blood boil and my eyes pop out of head.
Let's start by doing a little research. If the above statement is true, we should expect to find that the FDA HAS NEVER recalled Synthroid because of problems with stability or potency, and we would expect that the FDA HAS recalled natural thyroid pills because they are unstable, and vary in potency. So let's ask the FDA about this. What do we find? In reality, the FDA says Synthroid is unstable and varies in potency, while natural thyroid from RLC labs HAS NEVER been recalled for instablity or variation in potency.
Is Synthroid a Reliable and Stable Drug? No, Says the FDA.
Synthroid was marketed in 1955, but not FDA approved until July 24. 2002 because of a "history of potency failures...which indicates that Synthroid has not been reliably potent and stable."-- United States Food and Drug Administration Letter to Synthroid Manufacturer, Knoll Pharmaceuticals, April 26, 2001 (link )
Unstable, Not of Consistent Potency from Lot to Lot
Here is an FDA document August 14, 1997, Docket No. 97N-0314, which says:
"The drug substance levothyroxine sodium (also called Synthroid) is unstable in the presence of light, temperature, air, and humidity. Unless the manufacturing process can be carefully and consistently controlled, orally administered levothyroxine sodium products may not be fully potent through the labeled expiration date, or be of consistent potency from lot to lot.
There is evidence from recalls, adverse drug experience reports, and inspection reports that even when a physician consistently prescribes the same brand of orally administered levothyroxine sodium, patients may receive products of variable potency at a given dose. Such variations in product potency present actual safety and effectiveness concerns.
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