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Natural Thyroid and ERFA Thyroid: What's The Difference?

News September 3, 2021 | CanadaOnlineHealth

Millions of people have thyroid glands that don’t make enough thyroid hormone to meet their body’s needs.

Most people with hypothyroidism and Hashimoto’s Thyroiditis who take thyroid hormone medication are prescribed thyroid hormone replacement medications, which include two different categories: synthetic medication (which are man-made) or natural thyroid (which come from animals).

Medications Available to Balance Thyroid Hormones Include:

T4-only medications

  • Generic levothyroxine tablets
  • Synthroid tablets
  • Levoxyl tablets
  • Tirosint gel caps
  • Tirosint liquid (Tirosint SOL)
  • Compounded T4 medications

T3-only medications

T4/T3 combination medications

Differences Between Synthetic and Natural Thyroid Hormone

Synthetic L-thyroxine, or levothyroxine, only includes levothyroxine, also known as T4, such as Synthroid, Levoxyl, and Levo-T. After you take it, your body turns some of it into T3.

T3 is the active form of thyroid hormone, and if someone has problems converting T4 into T3 then they typically won’t do well when taking levothyroxine only. 

There may be multiple reasons why your body isn't doing enough converting of T4 to T3:

  • Gut microbiota imbalance
  • Lowered adrenal gland activity (adrenal fatigue)
  • Iron deficiency anemia

While the doctor can also prescribe a synthetic form of T3 such as Cytomel, many people prefer a natural option.

On the other hand, natural thyroid hormone includes both T3 and T4, along with small amounts of T1, T2, and calcitonin.

Natural Thyroid formulations are derived from desiccated porcine (pig) thyroid glands which have been used to treat thyroid problems for more than 100 years.

Because it is made from the whole gland, desiccated thyroid is considered a more complete product, providing supplementation of thyroid hormones closest to what would be produced naturally.

Many patients who do not feel well on conventional T4 treatments, have reported feeling much better after switching to natural thyroid medications.

Natural Desiccated Thyroid Extract

In the U.S, natural desiccated thyroid extract (DTE) medications include the brand names Armour Thyroid, Nature-Throid, NP Thyroid, and WP Thyroid.

Canada's desiccated thyroid is made by ERFA and called simply Thyroid.

All these brands consist of desiccated porcine thyroid powder, differing only in the binders and fillers.

Natural thyroid products are traditionally measured and available in “grains.” It is estimated that 1 grain of Armour Thyroid (or about 60-65 mg) is about the same as 100 mcg of levothyroxine (T4) or 25 mcg of liothyronine (T3).

Armour Thyroid

One grain of Armour is 60 mg, and it contains 38 mcg of T4 and 9 mcg of T3, along with very small amounts of T1, T2, and calcitonin.


One grain of Nature-Throid is 65 mg and contains 38 mcg of T4 and 9 mcg of T3, plus very small amounts of T1, T2, and calcitonin.

WP Thyroid

This used to be called Westhroid, and is made by the same manufacturers of Nature-Throid (RLC Labs).  One grain of WP Thyroid is 65 mg and contains 38 mcg of T4 and 9 mcg of T3, plus very small amounts of T1, T2, and calcitonin.

ERFA Thyroid

In general, 60 mg of ERFA thyroid is equivalent to 100 mcg of Synthroid or 25 mcg of liothyronine.

Some Thyroid Drugs Recalled Over Reduced Potency

FDA Voluntary Recall on Nature-Throid and WP Thyroid Products

On September 3, 2020, the Federal Drug Administration (FDA) announced a voluntary recall by RLC Labs, Inc. for all batches of Nature-Throid® and WP Thyroid®.

These products are being recalled due to sub-potency with amounts of liothyronine (T3) or levothyroxine (T4) lower than specified. This could result in patients not receiving the full dosage of their medications.

Acella Pharmaceuticals, LLC Issues Voluntary Nationwide Recall of Certain Lots of NP Thyroid® (Thyroid Tablets, USP) Due to Potency Issues

According to the U.S. Food and Drug Administration, Acella Pharmaceuticals, LLC, is recalling certain "15-mg, 30-mg, 60-mg, 90-mg and 120-mg NP Thyroid®, Thyroid Tablets, USP [levothyroxine (T4) and liothyronine (T3)]."

The company announced the voluntary recall on April 29, 2021. The announcement states that the medication is being recalled "because routine testing has found these lots to be sub potent."


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