🦋 Thyroid Hormone Panel Analyzer
Enter TSH, Free T4, and Free T3 values to screen for hyper/hypothyroidism.
What this tool does
It compares three common thyroid blood tests (TSH, free T4 and free T3) with typical adult reference ranges and names the pattern they fit. It is meant to help you understand your report before you see your doctor, not to diagnose a thyroid condition.
Units and ranges used
- TSH: mIU/L (the same as µIU/mL). Typical range about 0.4–4.5.
- Free T4: ng/dL. Typical range about 0.8–1.8. If your report is in pmol/L, divide by 12.87.
- Free T3: pg/mL. Typical range about 2.3–4.2. If your report is in pmol/L, divide by 1.536.
Every laboratory sets its own ranges. If your report prints different limits, trust those over the ones here.
What the patterns mean
- High TSH with low free T4: the usual pattern of an underactive thyroid (overt hypothyroidism).
- High TSH with normal free T4: subclinical hypothyroidism. Often repeated after 6–12 weeks before any decision, because TSH can rise temporarily after illness.
- Low TSH with high free T4 or T3: the usual pattern of an overactive thyroid (overt hyperthyroidism).
- Low TSH with normal free hormones: subclinical hyperthyroidism, also commonly re-checked.
- Normal TSH but free T4 or T3 out of range: uncommon. It can come from medicines, recent illness, a lab interference, or rarely a pituitary problem, so it needs your doctor’s review.
Things that change thyroid results
- Pregnancy uses different, trimester-specific ranges.
- Thyroid medicine taken shortly before the blood test, biotin supplements, steroids and amiodarone can all affect results.
- TSH is naturally a little higher in older adults and varies through the day.
If you are already on thyroid medicine, never change the dose based on this tool. Dose changes are made by your doctor.
Educational estimate only. Please discuss your results with your doctor.