The thyroid gland lies in front of the throat and produces two hormones — T4 and T3. These hormones control energy production in every cell of your body. When thyroid function is low, the tissues and organs cannot function at their best, leading to a wide range of symptoms that are often dismissed or misdiagnosed.
Symptoms of an Underactive Thyroid
An underactive thyroid — known as hypothyroidism — commonly causes fatigue, hair and skin problems, cold hands and feet, blood sugar imbalances, digestive issues, muscle and joint pain, and much more. These symptoms arise because every cell in the body depends on adequate thyroid hormone to produce energy.
How Do Thyroid Hormones Work?
The thyroid gland produces approximately one part T3 and two parts T4. T4 (also called levothyroxine) is a storage hormone that must be converted into the active thyroid hormone T3 — primarily in the liver. T3 is the hormone that directly increases cellular energy production. You can explore how thyroid hormones function in my book How to Use Thyroid Medication, which covers both natural and synthetic thyroid therapies in detail.
What Medications Are Used to Treat Hypothyroidism?
Thyroid replacement therapy can be either natural or synthetic. Natural desiccated thyroid (NDT) contains both T4 and T3, while most synthetic thyroid medications are based on T4 only — although some doctors do prescribe synthetic T3 alongside T4.
I believe that combination therapy using both T4 and T3 is the correct approach to treating hypothyroidism. You can learn exactly how to do this in my course Thyroid Recovery & Renewal™ and in my book How to Use Thyroid Medication.
What Is Natural Desiccated Thyroid?
Before synthetic thyroid hormones were developed, hypothyroidism was treated with natural desiccated thyroid (NDT) — an extract from porcine or bovine thyroid glands. Because the thyroid glands of pigs and cows are very similar to the human thyroid, this treatment was highly effective and is still widely used today.
Prescription NDT products include Armour Thyroid, Erfa Thyroid, and NatureThroid. There are also over-the-counter options, though the quality and thyroid hormone content vary considerably — something I cover in detail in my book How to Use Thyroid Medication.
Is Natural Thyroid Better Than Synthetic?
Porcine and bovine thyroid glands produce T4 and T3 in ratios very close to the human thyroid gland, making natural desiccated thyroid a reliable option for many people.
After synthetic thyroid hormones were developed, pure T4 (levothyroxine) quickly became the standard medical treatment. Common brand names include Eltroxin and Synthroid. However, a T4-only medication cannot replicate the full hormonal profile of natural desiccated thyroid, which contains both T4 and T3.
According to Dr. Ray Peat's research, treating hypothyroidism with T4 alone can create serious problems if the body is unable to efficiently convert T4 into T3. The correct approach is supplementation with both T4 and T3 — either through a natural thyroid extract or a synthetic combination therapy.
Is Levothyroxine Safe?
Early studies on T4 medication were conducted on healthy young men, in whom T4-to-T3 conversion was efficient and effective. However, women and people with more significant hypothyroidism often have difficulty converting T4 to T3 — particularly when liver function is compromised.
If your liver is not converting T4 effectively, a pure T4 medication may leave you undertreated. In my course Thyroid Recovery & Renewal™, I explain how diet and targeted nutritional support can improve liver function and T4-to-T3 conversion.
The T4 Conversion Problem
When T4 is not converted efficiently to T3, two serious problems can arise. First, you will remain undertreated because T4 is only a storage hormone — T3 drives cellular energy production. Second, T4 can accumulate in the tissues, and the body may convert the excess into reverse T3 (rT3), which has an anti-thyroid effect and can worsen your symptoms.
My book How to Use Thyroid Medication covers this in depth, including how to identify a T4 conversion problem and which combination therapies are most effective.
Thyroid Diet vs. Thyroid Medication
I always recommend addressing diet and lifestyle before turning to thyroid medication — for a detailed guide see my book How to Boost Metabolism with Food and my Metabolic Nutrition Mastery course. Many common Western diets — and even many healthy programmes — contain foods and substances that actively suppress thyroid function. Using the wrong diet can completely undermine even the best thyroid medication.
My course Thyroid Recovery & Renewal™ is built around this principle — combining the right thyroid-supporting diet with a clear framework for using medication safely and effectively. Diet and medication work best together, not in isolation.
How to Use Thyroid Medication Safely
Starting thyroid replacement therapy requires patience and careful monitoring. Begin at a low dose and increase gradually, tracking your pulse, temperature, and symptoms to assess how your body is responding.
For a complete step-by-step guide, my book How to Use Thyroid Medication walks you through the entire process — from choosing the right medication to monitoring your progress and adjusting your dose over time. My course Thyroid Recovery & Renewal™ gives you the broader framework for restoring thyroid health from the ground up.
FAQ: Thyroid Medication
Is T3 or T4 better for hypothyroidism?
Combination therapy with both T4 and T3 is generally more effective than T4 alone, especially for those with conversion difficulties. Natural desiccated thyroid contains both hormones in ratios close to the human thyroid gland.
What is reverse T3 and why does it matter?
Reverse T3 (rT3) is an inactive form of thyroid hormone produced when T4 accumulates in the tissues. High rT3 blocks T3 receptors and worsens hypothyroid symptoms even when blood tests appear normal.
Can I improve thyroid function without medication?
Diet and lifestyle changes can significantly support thyroid function. Many people see real improvement by removing anti-thyroid foods and adopting a pro-metabolic diet. However, those with significant hypothyroidism often need thyroid medication to fully restore function.
