Your labs say normal. Your body says otherwise.
Bio-identical T3/T4 thyroid support — for hypothyroidism, suboptimal thyroid function, post-thyroidectomy replacement, and the fatigue, weight gain, and brain fog that conventional T4-only therapy often fails to fully resolve. We test Free T3, not just TSH.
Hypothyroid symptoms are real even when TSH says normal.
Thyroid hormone therapy addresses hypothyroidism — but also goiter, thyroid nodules, post-thyroidectomy replacement, irregular periods, and libido issues tied to thyroid dysfunction. The T3/T4 system affects nearly every function in the body.
Thyroid hormones regulate metabolic rate at the cellular level — they determine how efficiently every cell converts nutrients to energy. When T3 (the active form) is low, cellular energy production slows systemically. The result is the distinctive fatigue of hypothyroidism: heavy, unrefreshing, present regardless of sleep.
Thyroid hormones directly regulate resting metabolic rate. With suboptimal T3, metabolic rate falls — making weight gain easier and weight loss harder even with caloric restriction and exercise. This is not a lifestyle problem; it's a metabolic one with a hormonal cause.
Impaired thermogenesis is a classic hypothyroid sign. When thyroid function is suboptimal, the body's heat production declines — producing persistent cold sensitivity, particularly in hands and feet, that isn't explained by the ambient temperature.
Thyroid hormones are essential for neurological function. T3 receptors are abundant in the brain, and suboptimal T3 levels produce the cognitive slowing, memory lapses, and concentration difficulties that characterize thyroid-related brain fog — often indistinguishable from estrogen-deficiency cognitive symptoms.
Hair thinning, brittle nails, and dry skin are among the most common presentations of hypothyroidism. These physical changes result from impaired cellular regeneration rates in high-turnover tissues. They often respond dramatically to thyroid optimization — though full reversal takes several months.
Thyroid hormone therapy is also used to treat goiter (enlarged thyroid gland), as hormone therapy for thyroid nodules, and to supply the necessary T3 and T4 in patients who have had a thyroidectomy. It additionally addresses libido, sexual function, and irregular menstrual cycles that have a thyroid component.
If your TSH is 'normal' but you have these symptoms, Free T3 may tell a different story.
Many patients come to us after years on T4-only therapy with persistent symptoms. We test the complete thyroid panel — TSH, Free T3, Free T4, and reverse T3 — and interpret it in the context of your symptoms, not just a reference range.
T4 is a storage hormone. T3 is the one that works.
The thyroid gland produces primarily T4 (thyroxine) — a relatively inactive storage hormone. T4 must be converted to T3 (triiodothyronine) in peripheral tissues to exert its biological effects. T3 is 3–5x more biologically active than T4 and is the form that actually enters cells and drives metabolic function. Standard hypothyroidism treatment — levothyroxine (Synthroid) — provides T4 only, relying entirely on the patient's ability to convert T4 to T3 in tissues. For many patients, this conversion is impaired — producing normal TSH and T4 levels while Free T3 remains suboptimal and symptoms persist.
Bio-identical thyroid support at Iuventus uses compounded T3/T4 combinations or desiccated thyroid extract (DTE) — preparations that provide both hormones in a ratio that more closely approximates natural thyroid secretion. This approach directly addresses the T4-to-T3 conversion problem that T4-only therapy cannot solve. Dosing is calibrated to Free T3 levels and symptom resolution — not to TSH normalization alone, which is an inadequate clinical endpoint for patients with conversion impairment.
TSH is the pituitary's signal to the thyroid — it reflects how hard the brain is telling the thyroid to work, not how much active T3 is actually in circulation. Many patients have normal TSH but suboptimal Free T3 because their T4-to-T3 conversion is impaired. If we only test TSH, we miss these patients entirely. Free T3 is the actual clinically relevant endpoint — and the number we optimize treatment to.
T3/T4 combination vs. T4-only therapy.
T4-only (levothyroxine) is the standard conventional treatment. T3/T4 combination addresses the conversion impairment that makes T4-only inadequate for a significant subset of patients.
| Feature | T3/T4 Combination ★ | T4-only (Levothyroxine) |
|---|---|---|
| Provides T3 directly | ✓ Yes | ✗ No — conversion dependent |
| Helps T4-to-T3 converters | ✓ Yes — directly | Only if conversion works |
| Dosing endpoint | Free T3 + symptoms | TSH normalization |
| Forms available | Compounded, desiccated thyroid (DTE) | Synthroid, generic levothyroxine |
| Onset of effect | Often faster — T3 acts directly | Depends on conversion rate |
| TSH suppression risk | Needs careful monitoring | Lower risk with T4 alone |
| Best for | T4-to-T3 conversion impairment, persistent symptoms on T4-only | Straightforward hypothyroidism, good T4 converters |
Thyroid optimization means Free T3, not just TSH.
The clinical evidence for T3/T4 combination therapy in patients with persistent symptoms on T4-only therapy continues to grow. A significant subset of hypothyroid patients have impaired T4-to-T3 conversion — a problem that T4-only therapy cannot address.
From 'your TSH is normal' to actually feeling well.
We review your thyroid history, prior treatments and their outcomes, current medications, and your complete symptom picture. If you've been on T4-only therapy with persistent symptoms, we're specifically looking for conversion impairment.
TSH, Free T3, Free T4, and reverse T3. We also test for thyroid antibodies (TPO, TGAb) to identify autoimmune thyroid disease (Hashimoto's). Your dose is calibrated to Free T3, not TSH alone.
Compounded T3/T4 or desiccated thyroid extract — selected based on your lab pattern, symptom profile, and prior treatment history. Dose starts conservatively and is titrated based on Free T3 response and symptoms.
Follow-up labs at 6 weeks. Free T3 and TSH checked. Dose adjusted for symptom resolution and to maintain TSH within a safe range. Ongoing monitoring every 3–6 months once stable.
Medicine that
gets you.
Thyroid optimization requires testing the right things and treating to the right endpoints. Most conventional thyroid management does neither. We do both.
We Test Free T3, Not Just TSH
TSH alone misses a significant subset of symptomatic hypothyroid patients. We always test Free T3 and Free T4 as part of our thyroid assessment — the measures that actually reflect tissue-level thyroid hormone activity.
T3/T4 Combination When Indicated
For patients with conversion impairment or persistent symptoms on T4-only therapy, we prescribe compounded T3/T4 or desiccated thyroid — addressing the problem T4 alone cannot solve.
Treated to Symptoms, Not Just Numbers
We optimize to Free T3 in the context of how you feel — not just to a TSH within the lab's reference range. A patient with TSH of 1.8 but Free T3 in the lower third of range and classic hypothyroid symptoms needs treatment, not reassurance.
Integrated with Full BHRT Panel
Thyroid symptoms closely mirror estrogen and progesterone deficiency symptoms. We test everything simultaneously — so we know which hormones are contributing to which symptoms, and treat accordingly.
Patients whose TSH
was 'normal.'
Everything you
want to know.
Hypothyroidism is treatable.
So is the fatigue it causes.
A complete thyroid panel — TSH, Free T3, Free T4 — and a protocol that treats to Free T3 optimization, not just TSH normalization. Free consultation.