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When it comes to thyroid health, “normal” lab test results don’t always tell the whole story. Many people still struggle with fatigue, weight changes, brain fog, and other stubborn symptoms—even when their numbers look fine on paper. That’s where the concept of optimal thyroid function comes in. 

True thyroid optimization is about more than numbers that fall in the normal range; it’s about personalized care, precise targets, symptom relief, and finally feeling like yourself again.

In this article, we’ll explore what optimized thyroid function really means, why the standard approach to treating hypothyroidism often falls short, and how you can take steps toward better relief and lasting wellbeing.

Before we dive into thyroid disorders, let’s start with the basics: how your thyroid actually works.

Your thyroid is a small butterfly-shaped gland in your neck, but don’t let its size fool you—it plays a significant role in keeping your body running smoothly. It’s part of your endocrine system, the network of hormone-producing glands that regulate everything from energy and mood to heart rate and body temperature.

Hypothalamus: The command center

The chain of command starts in your brain. The hypothalamus acts like a smart sensor, keeping tabs on your body’s needs. It communicates with the pituitary gland (often called the “master gland”), which then directs traffic for other glands—including the thyroid.

Enter the thyroid-hypothalamus feedback loop

Think of this as your body’s built-in thermostat.

1. The hypothalamus releases TRH (thyrotropin-releasing hormone).
2. TRH tells the pituitary to release TSH (thyroid-stimulating hormone).
3. TSH signals the thyroid to produce thyroid hormones – mainly thyroxine (T4) and triiodothyronine (T3) – which regulate metabolism, blood pressure, body temperature, and heart rate.

When thyroid hormone levels dip too low, the hypothalamus and pituitary crank things up, sending stronger signals to the thyroid to make more hormone. That’s a positive feedback mechanism.

On the flip side, when hormone levels get too high, the hypothalamus and pituitary ease off, telling the thyroid to slow down production. That’s a negative feedback mechanism.

When the system breaks down

Most of the time, this elegant feedback loop works beautifully to keep you in balance. But if one part of the system misfires—whether in the brain, pituitary, or your thyroid itself—the whole process can get thrown off, and you can end up without enough thyroid hormone, a condition known as hypothyroidism. 

Blood tests to help make a hypothyroidism diagnosis depend on the type of doctor you’re seeing. 

TSH test 

Many conventional doctors use only a TSH test to evaluate thyroid function and diagnose hypothyroidism.

While the normal reference range can vary slightly by laboratory, the general range for TSH tests falls between around .4 and 4.5 mIU/L. 

• If TSH is elevated above 4.5, it may be a sign that the body is underproducing thyroid hormones and can indicate hypothyroidism.‍
• If TSH is below .4, it may be a sign that the body is overproducing thyroid hormones, indicating hyperthyroidism. For thyroid patients who are taking thyroid hormone replacement medication, this may indicate that your dosage is too high. ‍
• If the TSH falls within the reference range, it may indicate that there is no thyroid dysfunction. 

However, the question we’re trying to answer is, do “normal” lab results always mean optimal thyroid function? Even if your lab results report normal TSH levels, you may still have symptoms indicative of thyroid dysfunction. To make that diagnosis, you need a complete thyroid blood panel to get the big picture.

A complete thyroid panel 

In addition to the TSH test, a complete thyroid blood test panel includes levels of free T4, free T3, and thyroid peroxidase antibodies (TPOAb). This is the test panel used by Paloma’s thyroid practitioners, and you’ll find integrative and holistic practitioners, as well as knowledgeable hormonal experts, using this set of tests to make a hypothyroidism diagnosis. 

The reference ranges for these tests are: 

• Free T4: 0.8–2.3 ng/dL
• Free T3: 2.0–4.4 pg/mL
• TPO antibodies: 0–35 IU/mL 

Free T4

Thyroxine (T4) is the primary hormone that is produced and secreted by the thyroid gland. Without enough free T4 (T4 that’s available for the body to use) (and its counterpart T3), your metabolism slows. T4 and T3 are in charge of your body’s energy usage. T4 is mostly inactive (called a storage hormone) and its primary function is to be converted into T3, the active hormone. Again, the reference range for free T4 is 0.8–2.3 ng/dL

• ‍If free T4 is high, it can indicate an overactive thyroid or hyperthyroidism.‍
• If free T4 is low, it can indicate an underactive thyroid or hypothyroidism.

Free T3

Triiodothyronine (T3) is the active thyroid hormone that works at the cellular level to help with the delivery of oxygen and energy to cells, tissues, and glands throughout the body. The body converts the storage hormone T4 into T3 to be used by cells. Without enough T3, the metabolism slows down. Free T3 is the available T3 circulating in your bloodstream.

• ‍If free T3 is high, it may indicate that your thyroid is overactive or hyperthyroid.‍
• If free T3 is low, it may indicate that the body is not effectively converting T4 into T3, and is consistent with hypothyroidism.

TPO antibodies (TPOAb)

The most common cause of hypothyroidism in the United States is Hashimoto’s thyroiditis, an autoimmune condition that damages your thyroid gland. When you have Hashimoto’s, your immune system produces antibodies against your thyroid gland. This antibody attack can lead to chronic inflammation and negatively affect the thyroid gland’s ability to produce thyroid hormone.‍

‍ If antibodies are elevated above the reference range, it suggests that your immune system is attacking your thyroid, indicating autoimmune Hashimoto’s thyroid disease.

Traditionally, doctors rarely test for thyroid antibodies. At Paloma Health, we believe it’s critical to measure Free Triiodothyronine (fT3), Free Thyroxine (fT4), and TPO antibodies.

Reverse T3

While it’s not a part of most thyroid panels, Paloma and other integrative medical practices often recommend an additional test for reverse T3 (rT3) to help identify thyroid dysfunction. Reverse T3 is an inactive form of the thyroid hormone T3 that’s produced when the body converts T4 into rT3 instead of active T3. Measuring rT3 can be helpful because high levels may indicate that your body isn’t efficiently converting T4 into usable T3—something that can happen with chronic illness, stress, or certain nutrient deficiencies. This test provides additional insight into thyroid function when standard labs don’t fully explain persistent symptoms. (Reverse T3 is available as an optional add-on to Paloma’s complete thyroid test kit.)  
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If your levels fall within the reference ranges, many health care providers will say that your thyroid is “normal.” In other words, you don’t have a thyroid condition. 

But let’s be clear about something first. Reference ranges are based on the average values in a population. These populations include people who already have thyroid dysfunction that has not yet been diagnosed, so the ranges often include levels that reflect existing thyroid disease. 

Doctors who use the “normal range” on lab tests as the only criterion for diagnosis often dismiss patients who have symptoms of hypothyroidism. In some cases, these patients may be misdiagnosed with other conditions that have similar symptoms. 

This is the problem with assuming that everyone feels well if their thyroid levels fall within the “normal” range. You can still be symptomatic—fatigued, depressed, gaining weight, and experiencing brain fog – even when your thyroid test levels fall within the normal range. Uniform reference values fail to account for individual variability, leading many patients to fall through the cracks. 

Optimal thyroid function is when your thyroid lab test values:

• Are well within a narrower range recommended by some thyroid specialists and functional practitioners
• Are accompanied by an absence of hypothyroid symptoms
• Account for individual patient history, comorbidities, and antibody status

Optimal ranges often cited by thyroid experts and functional practitioners, and used by Paloma’s practitioners, are:

• TSH: 0.4–2.0 mIU/L
• Free T4: 1.2–1.8 ng/dL
• Free T3: 3.2–4 pg/mL
• Thyroid peroxidase antibodies (TPOAb): < 35, and ideally closer to 0

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For most people with hypothyroidism, the cornerstone of treatment is thyroid hormone replacement therapy. The goal is simple but vital: restore thyroid hormone levels to an optimal range that relieves symptoms and supports overall health. How that’s achieved can vary, depending on the patient’s lab results, symptoms, and response to treatment.

The most commonly prescribed option is levothyroxine, a synthetic form of T4. Since T4 is converted into the more active T3 in the body, this treatment works well for many patients. However, some people do not efficiently convert T4 into T3, which can leave them with persistent symptoms even if their TSH and Free T4 levels appear “normal” on lab tests.

For those patients, alternatives may be considered. One option is a combination of synthetic T4 and synthetic T3 (liothyronine), which allows for more direct replacement of the active hormone. Another option is natural desiccated thyroid (NDT), derived from porcine thyroid glands. NDT contains both T4 and T3, as well as small amounts of T1, T2, and calcitonin—hormones that some patients feel provide a more “complete” replacement.

Many individuals with low Free T3, or those whose levels are technically in range but not in what’s considered the “optimal” zone, report improvement in energy, mood, weight management, and cognitive function when their treatment includes some form of T3.

That said, thyroid hormone replacement is not a one-size-fits-all therapy. The type of medication, dosage, and combination often need fine-tuning over time, with adjustments guided by both lab results and how the patient feels. Close monitoring and ongoing communication between patient and provider are essential to finding the right balance.
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What should you do if your thyroid levels are “normal,” but you still don’t feel well?

1. Find a provider or care team you trust, to partner with you.

2. Ask your provider for a complete thyroid panel, or take matters into your own hands with Paloma’s at-home thyroid test kit.

3. Work with your provider to consider all treatment options based on your symptoms, history, and lab results.

4. Consider your lifestyle, diet & nutrition, movement, sleep, and stress-management.

‍It’s time to get your thyroid back to optimal function! You can schedule a free call with Paloma to determine if Paloma Health is the right fit for you.

At Paloma Health, our focus goes beyond just getting our member patients into the “normal” range—we help you reach your optimal thyroid function, where symptoms improve and quality of life is restored.

Our approach is highly personalized. Instead of looking only at TSH, our providers also evaluate Free T4, Free T3, thyroid antibodies (like TPO), and reverse T3—while carefully considering your symptoms and health history. In some cases, we even explore genetic factors that may affect how well your body converts or absorbs thyroid hormones.

Because thyroid health is dynamic, achieving balance isn’t a one-time fix—it requires ongoing monitoring and adjustments. With Paloma Health’s at-home test kits, you can check your thyroid levels regularly without the hassle of scheduling lab visits and the pain of blood draws. This empowers you to catch changes early and work with your provider to fine-tune your treatment before symptoms spiral.

We also stay aligned with the latest research, which shows that “normal” lab values aren’t always good enough. Many patients feel best within narrower, more individualized ranges. That’s why our providers use advanced biomarkers, a personalized medicine approach, and outcome tracking to guide your care—always focused on how you feel, not just what your labs show.

Optimizing thyroid function means going beyond population-based reference ranges to target specific lab values that bring real relief from symptoms and sustained metabolic wellness. With Paloma Health, the future of thyroid care is here—personalized testing, nuanced protocols, and continuous monitoring that put your wellbeing, not just your numbers, at the center of care.
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• “Normal” thyroid lab results don’t always reflect optimal function—many patients still have symptoms despite being in range.
• Standard reference ranges are population-based and may include people with undiagnosed thyroid disease, making them less precise.
• A complete thyroid panel should include TSH, Free T4, Free T3, and thyroid antibodies, with reverse T3 as an optional but valuable marker.
• Optimal thyroid ranges are narrower than conventional ranges and emphasize both lab values and symptom improvement.
• Treatment often requires fine-tuning: some patients feel best with combination T4/T3 therapy or natural desiccated thyroid rather than T4 alone.
• Personalized, ongoing care—including at-home testing and close provider collaboration—supports lasting symptom relief and better thyroid health.

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