You got your bloodwork back. Your doctor says TSH is normal. But you’re still exhausted at 2pm, still gaining weight without explanation, still losing hair in the shower. Something is wrong — you know it — but the test says you’re fine.
This is one of the most common experiences in thyroid medicine. And it happens because TSH alone is an incomplete picture.
What TSH Actually Measures
TSH — thyroid-stimulating hormone — is produced by your pituitary gland, not your thyroid. It’s a signal your brain sends when it senses your thyroid hormone levels are low. When TSH is high, it means your pituitary is working hard to push more production. When it’s low, it means your pituitary has backed off.
What TSH does not tell you: how much actual thyroid hormone is circulating in your blood, how much your cells can actually use, or whether your thyroid is converting hormones efficiently.
“TSH is a thermostat reading, not a room temperature reading. It tells you what the control system thinks — not what’s actually happening in your body.”
The standard reference range for TSH is 0.4–4.0 mIU/L in most labs. But functional thyroid practitioners often work with a narrower optimal window of 1.0–2.5 mIU/L. A TSH of 3.8 is technically “normal” — but for many patients, it comes with real, disruptive symptoms.
The Three Axes: A Complete Thyroid Picture
A comprehensive thyroid evaluation looks at three markers together. At AxisThyroid, we call this the three-axis approach — because each one reveals something the others can’t.
Axis 1: TSH
Still essential. TSH is the first signal that something may be off. A persistently elevated TSH tells us the thyroid is struggling to keep up with demand. A suppressed TSH can signal hyperthyroidism or overmedication. But it’s the starting point, not the conclusion.
Axis 2: Free T4
T4 is the storage form of thyroid hormone. Your thyroid produces mostly T4, which then gets converted to T3 — the active form — in your liver, gut, and other tissues. Free T4 (as opposed to total T4) measures the hormone that isn’t bound to proteins and is actually available to your cells.
When Free T4 is low despite a normal TSH, it can indicate your thyroid is struggling to produce enough hormone. When Free T4 is normal but symptoms persist, the issue may be in conversion — and that’s where Free T3 becomes critical.
Axis 3: Free T3
T3 is the hormone your cells actually use. It drives metabolism, body temperature, heart rate, cognitive function, mood, and energy. If your body isn’t converting T4 to T3 efficiently — due to chronic stress, nutrient deficiencies, gut issues, or inflammation — your Free T3 will be low even when your TSH and Free T4 look normal.
Low Free T3 is one of the most underdiagnosed drivers of hypothyroid symptoms. It’s also not included in most standard thyroid panels.
Why Standard Panels Miss This
A typical primary care visit involves ordering a TSH. If it’s within range, the conversation ends. No Free T4. No Free T3. No thyroid antibodies (which could indicate Hashimoto’s disease, an autoimmune condition that accounts for the majority of hypothyroid cases in the US). This is especially common in New York thyroid evaluations, where insurance-driven practices rarely order beyond the basics.
This matters because:
- You can have normal TSH with low Free T3 — symptomatic but “normal” on paper
- You can have Hashimoto’s antibodies for years before TSH shifts at all
- You can be on levothyroxine (T4 medication) with normal TSH but still have poor T3 conversion — one of the most common signs thyroid medication isn’t working
- The optimal ranges for each marker aren’t the same as the lab reference ranges
The three-axis panel catches all of this. The standard one-marker test often doesn’t.
What a Three-Axis Evaluation Looks Like at AxisThyroid
Every AxisThyroid evaluation includes TSH, Free T4, and Free T3 as the baseline. Depending on your history, we may also add:
- TPO antibodies and anti-thyroglobulin antibodies to screen for Hashimoto’s or Graves’ disease
- Reverse T3 (rT3) when conversion issues are suspected
- Ferritin and Vitamin D, which affect thyroid hormone metabolism and are commonly low in thyroid patients
We interpret all markers together, in context of your symptoms — not against a reference range in isolation.
Bernadette Spencer, FNP-BC, FMACP — who founded AxisThyroid — was told for years that her own labs were “normal.” As a Hashimoto’s patient herself, she built this practice around the testing she wishes she’d had from the start.
What to Do If Your TSH Is “Normal” But You Still Feel Off
Ask for the full panel. Specifically: Free T3, Free T4, and TPO antibodies, in addition to TSH. If your current provider won’t order them, or dismisses your symptoms, you have options.
AxisThyroid provides telehealth thyroid care for New York residents. Your initial visit includes a full three-axis panel evaluation and a 45-minute consultation to review your results in context — not just against a reference range.
Get a Complete Thyroid Panel Evaluation
New York residents can complete intake online and get results reviewed by a clinician who specializes in thyroid — not a PCP fitting you into a 15-minute slot.
Start Your Intake →A TSH alone isn’t enough to explain how you feel. The three-axis approach gives a real picture. That’s where we start every evaluation.
Related Articles
- Telehealth Thyroid Care in New York: What to Expect
- 5 Hashimoto’s Diet Myths Your Doctor Never Corrected
- What to Expect: Your First 90 Days of Thyroid Optimization
- AxisThyroid Lab Panels: What We Test and Why
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