Free thyroid tool
Thyroid Lab Interpreter
Enter your TSH, Free T4, Free T3 and anti-TPO results to see how each value compares with its typical adult reference range, then get a calm, plain-language explanation. Educational only — your doctor interprets your case.
The four markers
What a thyroid panel measures
A standard thyroid panel usually reports these four markers. The ranges below are typical adult reference ranges — your own laboratory's interval may differ, so always read your result against the range printed on your report.
| Marker | What it measures | Typical range |
|---|---|---|
| TSHThyroid-stimulating hormone | How hard your pituitary is signalling the thyroid to produce hormone. | 0.4–4.0 mIU/L |
| Free T4Free thyroxine | The unbound thyroid hormone available to your tissues. | 0.8–1.8 ng/dL · 12–23 pmol/L |
| Free T3Free triiodothyronine | The active thyroid hormone your cells actually use. | 2.3–4.2 pg/mL · 3.5–6.5 pmol/L |
| anti-TPOThyroid peroxidase antibodies | Antibodies against the thyroid enzyme TPO — a marker of autoimmunity. | <35 IU/mL |
How to read it
How to read your thyroid panel
Doctors rarely read a single number in isolation. TSH comes from your pituitary and tends to move in the opposite direction to your thyroid hormones — when thyroid hormone is low, TSH usually rises. Free T4 and Free T3 show how much active hormone is actually available to your body. Anti-TPO antibodies point to autoimmunity but do not, by themselves, define how you feel. What matters most is the whole pattern over time, read alongside your symptoms.
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FAQ
Common questions
What is a normal TSH level?
For most adults the typical reference range for TSH is about 0.4–4.0 mIU/L, though the exact interval varies by laboratory, assay, age and whether you are pregnant. A value inside that band is generally considered typical, but only your doctor can interpret it in the context of your symptoms and other results.
What does a high anti-TPO (TPO antibody) level mean?
Thyroid peroxidase antibodies above roughly 35 IU/mL are often described as elevated and can indicate thyroid autoimmunity. Many people have detectable antibodies without any thyroid problem, and levels do not map neatly onto how you feel. An elevated result is something to review with your healthcare provider — it is not a diagnosis on its own.
What is the difference between Free T4 and Total T4?
Total T4 measures all the thyroxine in your blood, most of which is bound to proteins and inactive. Free T4 measures only the unbound fraction that is actually available to your tissues, so it is usually the more clinically useful of the two. This tool uses the Free T4 typical range of about 0.8–1.8 ng/dL (≈12–23 pmol/L).
Can I diagnose myself from these results?
No. This tool is educational only. It shows how your entered values compare with typical adult reference ranges and explains what each marker measures, but it cannot diagnose a condition, account for your full medical history, or replace a clinician. Always review your labs with your healthcare provider.
Why do reference ranges differ between laboratories?
Different labs use different testing methods, equipment and calibration, and they set their own reference intervals from their local population. That is why the range printed on your report may not match a range you read online. Always compare your value with the range on your own lab report.
For educational purposes only. Not medical advice, not a diagnosis. Reference ranges vary by laboratory and assay. Always consult your healthcare provider to interpret your results and before making any change to your care.