Thyroid Conversion Guide: WP Thyroid and Nature-Throid

This conversion chart can help you compare the dosages of different types of synthetic and natural hormone therapies. Please note that each grain of WP Thyroid or Nature-Throid contains 38 mcg of T4 and 9 mcg of T3.

Natural Thyroid vs. Synthetic Thyroid (Armour, Synthroid, Tirosint)
*Strengths limited to Armour® Thyroid
Armour® is a registered trademark of Allergan, Inc.
NP Thyroid® is a registered trademark of Acella, LLC.

Source: United States Pharmacopoeia - Drug Information 2000, 20th Edition

Talk to your doctor about whether natural thyroid hormone replacement is best for you, and what dosage will best suit your medical needs.

Frequently Asked Questions

What Does T4 Do?

Thyroxine, often called T4, affects almost every cell in your body! It plays roles in3:

  • Metabolism of proteins, fats, carbohydrates, and vitamins
  • Basal metabolic rate (the rate at which you use energy)
  • Long bone growth
  • Protein synthesis
  • Nervous system development

What Is T3 Hormone?

Triiodothyronine (T3) is made by enzymes called deiodinases acting on T4. Like T4, it has many functions, such as playing roles in growth and development, body temperature, and heart rate1.

Is T3 or T4 More Active?

T3 is more active--about three to four times more potent than T4--because it is easier for cells to take up and utilize T31, though it also has a shorter half-life than T45.

What Does Levothyroxine Do for the Thyroid?

Levothyroxine doesn't actually affect the thyroid gland2; it provides the body with the T4 hormone that the thyroid is failing to produce5.

How Can I Improve Conversion of T4 to T3?

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

  • Gut microbiota imbalance1
  • Lowered adrenal gland activity (adrenal fatigue)1
  • Iron deficiency anemia1

One way to get enough T3 is through hormone replacement therapy4. Talk to your doctor today to see if T4 + T3 combination therapy is right for you.


1. Childs, Westin. How to Increase Free T3 Levels Naturally: 8 Step Guide + Tips and Tricks. Restart Med. 2016 March.

2. Cooper, D. S. Thyroid hormone treatment: New insights into an old therapy. Journal of the American Medical Association. 1989 May, 261(18): 2694-2695.

3. Lichten, Edward M. Synthetic Thyroxine vs. Desiccated Thyroid. Journal of the American Medical Association. 2004 March, 291(12): 1445.

4. Thyroid Hormone Replacement Therapy. Johns Hopkins Medicine. 2016 October, par. How is thyroid replacement therapy dosage determined?

5. Wiersinga, W. M. Thyroid Hormone Replacement Therapy. Hormone Research in Pediatrics. 2001 May, 56(suppl 1): 74-81.