Thyroid Report Decoder
Enter the values from your thyroid report. Thyroid values are always read as a pattern — TSH together with T4 — and the decoder explains each value and the combination in plain language.
Normal: 0.4–4.5 mIU/L
Normal: 0.8–1.8 ng/dL
Normal: 2.3–4.2 pg/mL
Normal: 5–12 µg/dL
Normal: 0–34 IU/mL
Frequently Asked Questions
What is the normal range for TSH?
The usual adult range is about 0.4–4.5 mIU/L (some labs and guidelines use up to 4.0 or 5.0). In pregnancy the targets are lower and trimester-specific — pregnant readers should use the ranges their doctor gives.
What does high TSH with normal T4 mean?
That pattern is called subclinical hypothyroidism: the thyroid is starting to struggle but T4 is still maintained. Doctors often repeat the test in 6–12 weeks and check Anti-TPO antibodies before deciding on treatment.
What does low TSH mean?
Low TSH usually means an overactive thyroid (hyperthyroidism) or too high a dose of thyroxine medicine. With a high Free T4 it is overt hyperthyroidism; with normal T4 it is subclinical and still needs medical follow-up.
Can one abnormal thyroid value be a mistake?
Yes — illness, biotin supplements, pregnancy and some medicines can distort thyroid results, and ranges differ between labs. Unexpected results are usually confirmed with a repeat test before treatment changes.
Go deeper: read the full Biochemistry hub guide, or try the main Report Decoder.