Animal Thyroid Supplements for Hypothyroidism

Is It the Safest Option?

Though synthetic thyroid hormones are the preferred medication for hypothyroidism today, animal thyroid hormones (also known as desiccated, or dried, thyroid extract) were once the standard treatment. In fact, they were the only treatment available.

Doctors began using extracts of animal thyroids in the late 1800s. But in the early 1960s, the development of synthetic thyroid hormones overshadowed animal hormones in doctor approval. Since then, animal thyroid hormones have taken a back seat to synthetic hormones.

In this Article

Armour Thyroid: Is It Safe?
However, animal thyroid medications are still available today—the most popular brand being Armour Thyroid. This supplement, made from desiccated pig thyroid glands, is a combination of both T4 and T3 hormone.

Other animal thyroid hormone brands include Westhroid and Nature-Throid. Both brands are made from desiccated pig thyroid glands. The only difference is that Westhroid pills are bound with cornstarch, while Nature-Throid contains microcrystalline cellulose instead of cornstarch (for patients who are allergic).

Animal thyroid hormones are considered all-natural supplements, which is certainly part of their allure for patients who prefer natural over synthetic medications. However, natural doesn't always mean it's the safest option.

That said, doctors greatly prefer synthetic thyroid hormones for a variety of reasons, mainly because:

  • Animal thyroid pills aren't purified, which means that they contain substances that aren't naturally found in humans. Researchers have yet to determine how these substances affect the human body. Synthetic pills, on the other hand, are a pure form of the hormones produced in your body. While they are called "synthetic," these medications are actually identical to the compound (T4) that the body produces naturally.
  • The amounts of T4 and T3 in animal thyroid pills vary among manufacturers and brands, so they're not as precise as their synthetic counterparts. This can make it even harder to find your ideal hormone dosage. Also, the preparations from any single manufacturer over time will also vary. For instance, a perfect dose one month may be too much or too little a couple months down the road when the next batch comes on the market.
  • The hormone balances in animals aren't the same as humans, so it's difficult to argue that animal thyroid hormones are truly natural for humans.

Animal Thyroid Hormones vs Synthetic Thyroid Hormones
Many patients often believe animal thyroid hormones are better because they contain both T4 and T3. The most common practice is to treat people with T4 since the half life of T4 is longer (7 days versus 1 day for T3) and body will naturally convert some of it to T3. However, there are synthetic T3 supplements now available by prescription. Most of the time, T3 supplements are used in preparation of the patients for radioactive ablation in case of thyroid cancer after thyroidectomy due to the shorter half life.

For these reasons, the great majority of physicians believe synthetic thyroid hormones are the safer treatment option. Animal thyroid hormones, however, can still help manage hypothyroidism for patients who prefer that alternative knowing the disadvantages outlined above.