Thyroid Health: What You Need About Hormone Optimization

Discover how thyroid health and hormone optimization can lead to improved balance and vitality in your daily life.

Abstract

In this educational post, I walk you through how low thyroid function can persist despite “normal” labs, why the enzyme-driven conversion from T4 to the active hormone T3 is central to metabolism and mood, and how modern evidence clarifies the limits of TSH-only screening. I present the latest insights into non-thyroidal illness syndrome (low free T3 with normal TSH), explain the difference between reference ranges and optimal ranges, and outline how stress, aging, restrictive dieting, insulin resistance, and certain medications can blunt T4-to-T3 conversion. I also share how our multidisciplinary team in El Paso, Texas—led by me, Dr. Alex Jimenez, DC, APRN, FNP-BC, CFMP, IFMCP, ATN, CCST, and our Medical Director and Collaborative Physician, Dr. Maria Guadalupe Cardenas, MD (Board Certified in Internal Medicine; NPI #1164426749; Texas MD License #J2933)—integrates chiropractic care, internal medicine, functional medicine, rehabilitation, and personal injury services to deliver precision thyroid care. You will learn how we combine integrative chiropractic care, medical oversight, nutraceuticals, lifestyle interventions, and, when appropriate, targeted thyroid medications to restore cellular thyroid signaling. Clinical observations from my practice at Injury Medical Clinic PA (Mission Plaza Injury Medical Clinic) enrich this narrative with real-world outcomes and practical steps patients can take today.

Optimizing Thyroid Health: Why “Normal” Labs Don’t Always Mean Normal Physiology

When I first began focusing on thyroid health nearly two decades ago, I kept meeting patients—especially women over 45—who had persistent symptoms even after we optimized other hormones. They described cold hands and feet, dry skin, thinning hair or eyebrows, constipation and bloating, mild anxiety and depression, fatigue, and difficulty losing weight. Their primary care reports often labeled their thyroid “normal” because thyroid-stimulating hormone (TSH) levels fell within reference limits. Yet clinically, they looked and felt hypothyroid.

This disconnect led me deeper into the physiology and the literature. The core revelation: TSH is a screening signal, not a complete thyroid story. TSH rises when circulating thyroxine (T4) is low and falls when T4 is high, reflecting a brain-thyroid feedback loop. However, the hormone that drives cellular metabolic activity is triiodothyronine (T3)—particularly free T3, the unbound, bioavailable fraction that can enter cells and activate nuclear receptors. Crucially, T3 does not meaningfully regulate TSH. That means a person can have normal T4 and normal TSH while still having low free T3, resulting in textbook hypothyroid symptoms.

In our clinic, we evaluate a full panel—TSH, free T4, and free T3—to illuminate the true physiologic status. When free T3 is suboptimal, we see predictable symptom clusters, and patients often feel dismissed if nobody measured T3 in the first place.

How Thyroid Works: The T4-to-T3 Conversion and Why Free T3 Is the Metabolic Driver

The thyroid gland secretes predominantly T4 (~80%) and a smaller fraction of T3 (~20%). In tissues such as the liver, kidney, and skeletal muscle, the enzyme deiodinase type 1 (DIO1) converts T4 (a pro-hormone) into T3 (the active hormone). T3 enters cells, binds thyroid hormone receptors (TRα and TRβ), and modulates gene transcription, boosting mitochondrial biogenesis, oxygen consumption, ATP production, ion pump activity, and macromolecule turnover. This is why T3 is a metabolic accelerator—it governs thermogenesis, basal metabolic rate, lipid and glucose handling, gastrointestinal motility, skin and hair integrity, mood regulation, and even cardiac chronotropy and inotropy.

When DIO1 activity dips, T4-to-T3 conversion falls, free T3 declines, and the body downshifts: energy drops, heat production falls, gut slows, mood dims, and weight loss becomes difficult despite effort. This “low free T3 with normal TSH” pattern is commonly referred to as non-thyroidal illness syndrome (NTIS) or low T3 syndrome. However, many patients have this outside of acute illness—particularly under stress, aging, or restrictive calorie states.

Why Reference Ranges Mislead: Population Norms vs. Optimal Health

Most lab reference ranges reflect population averages, not peak health. In free T3 panels, the lower end of the “normal” range may still associate with higher inflammation, cardiometabolic risk, and worse quality of life. Pediatric data show healthy young adults frequently sit near the high end of free T3 distributions. Clinically, we find that patients feel and function better when free T3 is in the upper third of the laboratory reference range (often around 4.0–5.0 pg/mL, depending on the assay), provided there are no signs of hyperthyroidism. The analogy I give patients is this: you don’t aim for the left side of the bell curve on an exam—you aim rightward, toward the optimal performers. With hormones, “optimal” distributions matter for outcomes.

Latest Evidence: What Suppresses T4-to-T3 Conversion

Modern research consistently links several factors to impaired DIO1 activity and lower free T3:

• Chronic psychological stress and elevated glucocorticoids blunt DIO1 and favor production of inactive reverse T3 (rT3), which competes with T3 at receptors without delivering metabolic benefits (Fliers et al., 2015; van der Spek et al., 2017).
• Restrictive calorie intake, rapid weight loss, and prolonged fasting reduce DIO1 as the body “defends” against perceived famine by lowering metabolic drive (Mullur et al., 2014).
• GLP-1 agonist therapy (e.g., semaglutide, tirzepatide) can lead to reduced appetite and caloric intake. At the same time, these agents improve glycemic control and weight; abrupt caloric restriction often shows a concurrent lowering of free T3 in real-world patients, consistent with the adaptive downshift of metabolism (Klein, 2004; Tee et al., 2010).
• Aging naturally reduces deiodinase activity and receptor sensitivity, contributing to lower free T3 levels even with normal TSH (Jonklaas et al., 2014).
• Insulin resistance and systemic inflammation disrupt thyroid hormone transport and conversion, often manifesting as lower free T3 and higher rT3 (Gonçalves et al., 2019).
• Certain medications and even T4-only therapy in some patients can leave free T3 suboptimal, because normalizing TSH with T4 doesn’t guarantee adequate tissue T3 (Escobar-Morreale et al., 1995; Wiersinga, 2014).

These mechanisms map tightly to what we observe clinically: patients with high stress loads, long-term fasting or calorie restriction, low-protein diets, sedentary lifestyles, or chronic metabolic dysfunction often present with normal TSH but low free T3—and the classic symptom constellation.

Evidence-Guided Testing: What We Order and Why

Our protocol emphasizes a nuanced panel:

• TSH: to screen for primary thyroid gland under- or over-activity.
• Free T4: to understand circulating pro-hormone availability.
• Free T3: to assess active hormone availability at the cellular level.
• Optional in select cases: rT3, thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb), lipid panel, fasting glucose and insulin, HbA1c, CRP, ferritin, vitamin D, B12, and iron studies—because nutrient status and inflammation modulate thyroid signaling.

We interpret these in the context of symptoms, vital signs, body composition, heart rate variability, sleep, GI function, and musculoskeletal status. Our clinical observations at Injury Medical Clinic PA mirror what I share publicly in articles and on LinkedIn: when patients’ free T3 moves from the low-normal to the optimal range, we commonly see improvements in energy, mood, thermoregulation, bowel regularity, hair and skin quality, and exercise recovery.

Integrated Care in El Paso: Internal Medicine Oversight and Chiropractic Synergy

At Injury Medical Clinic PA (Mission Plaza Injury Medical Clinic) in El Paso, Texas, our multidisciplinary model places thyroid care within a broader framework of whole-person health. I, Dr. Alex Jimenez, DC, APRN, FNP-BC, CFMP, IFMCP, ATN, CCST, work closely with our Medical Director and Collaborative Physician, Dr. Maria Guadalupe Cardenas, MD (Board Certified in Internal Medicine; NPI #1164426749; Texas MD License #J2933), who brings over 40 years of internal medicine experience. This is the integrative clinic model at its best: an MD provides medical direction alongside a chiropractor, ensuring safety, medication stewardship, and evidence-based alignment.

Our team integrates:

• Internal medicine oversight (Dr. Cardenas) for diagnostics, medical risk management, and targeted pharmacotherapy when indicated.
• Integrative chiropractic care (Dr. Jimenez) to optimize neuromusculoskeletal function, autonomic balance, and movement patterns that enhance metabolic signaling.
• Functional medicine protocols to address root causes: stress, sleep, micronutrient status, gut dysbiosis, insulin resistance, and chronic inflammation.
• Rehabilitation and personal injury care to restore biomechanics, reduce pain-driven stress responses, and support activity resumption.
• Nutrition and lifestyle medicine for tailored macronutrient intake, protein adequacy, micronutrient sufficiency, and sustainable weight strategies—especially for patients on GLP-1 drugs.

How Integrative Chiropractic Care Supports Thyroid Physiology

Patients often ask how chiropractic care fits into a thyroid plan. The connection is through the autonomic nervous system, movement, and inflammation:

• Autonomic regulation: Chronic sympathetic overdrive elevates cortisol and catecholamines, thereby reducing DIO1 and lowering free T3. Chiropractic adjustments, soft tissue therapies, and structured breathing can shift autonomic tone toward parasympathetic balance, improving stress resilience and potentially supporting T4-to-T3 conversion (Martins et al., 2018).
• Pain reduction and sleep improvement: Musculoskeletal pain fuels stress and sleep fragmentation; effective spine and joint care reduces nociceptive signaling, thereby aiding restorative sleep and circadian rhythm alignment—both of which are key to hormone homeostasis.
• Movement as a metabolic signal: Personalized mobility, core stabilization, and resistance-training routines increase mitochondrial activity and insulin sensitivity, thereby improving thyroid hormone action in target tissues. We employ graded exercise prescriptions that match the patient’s current capacity to avoid overtraining, which can suppress T3.
• Inflammation mitigation: Myofascial release, posture correction, and ergonomic coaching reduce local and systemic inflammatory drivers that impair thyroid receptor function and hormone transport.

In clinical observations documented across my practice platforms, including dralexjimenez.com and LinkedIn, patients with low free T3 frequently report improved energy and mood once we combine autonomic-calming strategies, movement therapy, and targeted nutrient repletion. This synergizes with medical adjustments under Dr. Cardenas’ guidance.

Nutrients and Lifestyle: Why We Target Inputs That Support DIO1 and Thyroid Signaling

DIO1 is a selenoprotein enzyme; adequate selenium is essential. Zinc supports thyroid hormone synthesis and receptor function. Iron (via ferritin) is necessary for thyroid peroxidase activity and oxygen delivery. Vitamin D modulates immune function and may influence autoimmunity and metabolic health. Protein intake provides tyrosine, the backbone for thyroid hormone synthesis, and supports hepatic deiodinase activity.

Our core recommendations:

• Ensure adequate dietary protein (generally 1.2–1.6 g/kg/day for most non-renal-compromised adults; individualized).
• Replete selenium (commonly 100–200 mcg/day as selenomethionine, if deficient), zinc (10–30 mg/day, balanced with copper as appropriate), and iron when ferritin is low, under medical supervision.
• Optimize vitamin D toward 60–100 ng/mL, consistent with reduced cardiometabolic risk profiles when individualized to patient context.
• Stabilize circadian rhythms: consistent sleep-wake times, morning light exposure, evening light minimization.
• Implement stress-mitigating practices: box breathing, paced respiration, meditation, and heart rate variability feedback.
• Avoid long-term aggressive caloric restriction; use gentle deficits and periodic refeeds to maintain thyroid signaling, especially on GLP-1 therapies.

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THYROID DYSFUNCTION ***MUST WATCH*** (Assessment and treatment)- Video

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GLP-1 Medications: Powerful Tools That Require Thyroid-Aware Strategy

Semaglutide and tirzepatide are transformative for weight and insulin resistance. However, when appetite suppression drives prolonged low-calorie intake, free T3 often falls. Under Dr. Cardenas’ medical oversight, we:

• Monitor TSH, free T4, and free T3 during weight loss.
• Encourage adequate protein and micronutrient intake, along with resistance training, to preserve lean mass and metabolic rate.
• Consider cycling caloric intake or adding maintenance phases.
• If persistently low free T3 is present and accompanied by symptoms, consider targeted thyroid therapy.

When and Why We Use Thyroid Medication

Not all patients need medication. If lifestyle, chiropractic-integrative methods, and nutrient repletion restore free T3 and resolve symptoms, that’s ideal. But for persistent low free T3 with clinical impairment, we consider:

• Desiccated thyroid (e.g., NP Thyroid, Armor Thyroid, Avexathroid): provides both T4 and T3, which can raise free T3 into an optimal range. Many patients feel better when free T3 is 0.0–5.0 pg/mL, without hyperthyroid signs.
• T4/T3 combination therapy: individualized ratios based on labs, symptoms, and patient goals.
• T4-only therapy: appropriate in primary hypothyroidism where the gland underproduces; some patients still need low-dose T3 add-on if free T3 remains low despite normalized TSH.

Myth-busting: “If I Start Thyroid Medication, I’ll Need It Forever”

This depends on etiology. In primary hypothyroidism (elevated TSH due to thyroid gland failure), lifelong therapy is typical. But in conversion-related low free T3—due to stress, dieting, aging, insulin resistance—low-dose combination therapy can be a bridge. If you resolve the drivers later, you may taper off under medical supervision. The pituitary-thyroid axis operates on feedback loops; stopping exogenous hormone allows endogenous signaling to resume. This is not a one-way suppression unless the gland itself is failing.

Clinical Flow: How Our Team Delivers Precision Thyroid Care

• Intake and assessment: full symptom inventory, medical history, injury status, sleep/stress profile, diet and activity review.
• Laboratory evaluation: TSH, free T4, free T3, plus adjunct markers as indicated.
• Chiropractic and rehabilitation baseline: spinal and joint function, autonomic tone, movement patterns.
• Integrated plan:

• • Medical oversight (Dr. Cardenas): ensure safety, rule out nodules or autoimmune disease, adjust medications if indicated.
  • Chiropractic care (Dr. Jimenez): autonomic-balancing adjustments, soft tissue work, graded movement therapy.
  • Functional medicine: nutrition, micronutrient repletion, stress protocols, GI optimization.
  • Monitoring: regular lab checks and symptom tracking; iterative therapy tuning.

• Outcomes: improved thermoregulation, mood, energy, GI motility, hair/skin quality, exercise tolerance, and weight stability.

Why Patients Feel Better When Free T3 Is Optimized

At the cellular level, adequate T3:

• Upregulates mitochondrial enzymes, increasing ATP and heat production, reducing fatigue and cold intolerance (Silva, 2006).
• Enhances GI smooth muscle motility, improving constipation and bloating.
• Modulates neurotransmitter systems and neurotrophic signaling, which correlates with reduced depressive symptoms in some patients (Bauer & Whybrow, 1990).
• Improves cardiac performance at physiologic ranges, supporting activity tolerance.
• Accelerates the turnover of skin and hair follicles, restoring quality with adequate micronutrient intake.

Our clinical observations confirm: when we move free T3 into the optimal range while calming stress, normalizing sleep, and promoting intelligent movement, patients reclaim vitality. This is not placebo—it is cellular biology expressing itself under appropriate hormonal conditions.

Practical Steps You Can Start Today

• Request comprehensive thyroid labs: TSH, free T4, and free T3.
• Track symptoms: cold intolerance, dry skin/hair, constipation, fatigue, mood changes, palpitations, weight resistance.
• Ensure protein adequacy and micronutrient sufficiency (selenium, zinc, iron, vitamin D).
• Avoid chronic severe calorie restriction; use sustainable nutrition plans with resistance training.
• Implement stress-calming practices daily: a consistent sleep schedule and morning light exposure.
• Partner with a team that integrates medical oversight, chiropractic care, and functional medicine.

Our Commitment in El Paso

I’m proud to work alongside Dr. Maria Guadalupe Cardenas, MD, whose four decades in internal medicine anchor our protocols in safety and scientific rigor. In a city known for resilience and community, we bring that same spirit to our patients at Injury Medical Clinic PA. Whether you’re recovering from an injury or navigating complex metabolic challenges, your thyroid health is central to how you heal, move, and live.

For ongoing insights and case-based observations, I share updates and clinical reflections at dralexjimenez.com and on LinkedIn. Our educational mission is to make complex physiology understandable and actionable so that you can see your progress in the mirror, the lab report, and how you feel day to day.

References

• Exploring the thyroid axis in health and disease: mechanisms of non-thyroidal illness syndrome (Fliers, E., Bianco, A. C., Langouche, L., & Boelen, A., 2015). Journal of Clinical Endocrinology & Metabolism.
• Thyroid hormone: regulation of metabolism and thermogenesis (Silva, J. E., 2006). Thyroid.
• Thyroid hormone conversion, deiodinases, and aging-related changes (Jonklaas, J. et al., 2014). Journal of Clinical Endocrinology & Metabolism.
• Interplay between insulin resistance and thyroid function iGonçalves, C., et al., 2019). Endocrine Connections.
• Calorie restriction and thyroid hormone changes (Klein, S., 2004). New England Journal of Medicine.
• Reverse T3 and non-thyroidal illness (van der Spek, A. H., et al., 2017). Journal of Clinical Endocrinology & Metabolism.
• Persistent symptoms in hypothyroid patients on levothyroxine (Wiersinga, W. M., 2014). Journal of Clinical Endocrinology & Metabolism.
• Combination therapy vs monotherapy in hypothyroidism (Escobar-Morreale, H. F., et al., 1995). European Journal of Endocrinology.
• Exercise, autonomic balance, and endocrine function (Martins, L. C., et al., 2018). Frontiers in Physiology.
• Metabolic adaptation to weight loss and thyroid hormones (Tee, M. C., et al., 2010). American Journal of Clinical Nutrition.
• Thyroid hormone augmentation in depression (Bauer, M., & Whybrow, P. C., 1990). Psychoneuroendocrinology.

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