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A Different Thyroid Approach?

Perhaps you have been on thyroid replacement for some time due to your hypothyroidism. However, you still feel sluggish, have difficulty losing weight, and other common low thyroid symptoms. Your prescription thyroid medication is one of the common forms of Levothyroxine, often referred to as Synthroid or Levoxyl. Indeed, these thyroid medications are among the most common thyroid medications in America. What you may find interesting is that several studies show that many people on thyroid replacement prefer a different type of thyroid replacement.

You Need Active T3

Several studies have determined that many hypothyroid patients feel improvement in their low thyroid symptoms better from Levothyroxine or the combination of Levothyroxine and Liothyronine. For background information, your thyroid produces both T4 (Levothyroxine) and T3 (Liothyronine) hormones. Both have activity in the body but T3 is much more metabolically active, even though much smaller amounts are produced. Moreover, the T4 produced by the thyroid is also converted by enzymes in the liver and kidneys. This is why people with liver and kidney disease can be more prone to low thyroid, as well as people who have decreased function of these organs due to toxicity.

Genetic Issues

There is also more to the story. Researchers have identified a gene variation (Thr92Ala-type II iodothyronine deiodinase (DIO2)-polymorphism) that can make it more difficult to convert T4 to the more biologically active T3. In other words, some people have a genetic issue that makes it more difficult to form the active T3 from T4. Research demonstrates this gene variation affects between 12%-36% of the population. So, if you are taking the common medication Levothyroxine then you have up to a 36% likelihood you are not going to make the critical T3 hormone. One of the solutions to this problem is to prescribe to the patient both T4 and T3 hormones. There are a few different ways to do this:

  1. Continue Levothyroxine and added Liothyronine (T3) as a separate prescription
  1. Use Desiccated Thyroid Extract, such as Nature-Throid® or Armour-Thyroid®
  1. Use compounded thyroid, where a compounding pharmacy creates the precise dose of T4 and T3

T4/T3 Combination Vs T4 Only Study

In a recent meta-analysis involving 18 studies and over 1500 participants (mainly female), researchers found that patients preferring the combination T4/T3 therapy was 43% compared to T4 only at 23%.


If you are on thyroid replacement and not satisfied with how you are feeling, then consider combination T4/T3 therapy. Dr. Angela and I work with these thyroid prescriptions extensively with patients at the Stengler Center.

Dr. Mark Stengler NMD, MS, is a bestselling author in private practice in Encinitas, California, at the Stengler Center for Integrative Medicine. His newsletter, Dr. Stengler’s Health Breakthroughs, is available at and his product line at


Bianco, A. C., & Kim, B. S. (2018). Pathophysiological relevance of deiodinase polymorphism. Current opinion in endocrinology, diabetes, and obesity, 25(5), 341–346.

Millan-Alanis, J. M., González-González, J. G., Flores-Rodríguez, A., Singh Ospina, N., Maraka, S., Moreno-Peña, P. J., Brito, J. P., González-Velázquez, C., & Rodríguez-Gutiérrez, R. (2021). Benefits and Harms of Levothyroxine/L-Triiodothyronine Versus Levothyroxine Monotherapy for Adult Patients with Hypothyroidism: Systematic Review and Meta-Analysis. Thyroid : official journal of the American Thyroid Association, 31(11), 1613–1625.