Understanding your thyroid panel: a plain-language guide
Womezo Health Team
9 min read · Reviewed against current clinical reference standards
If you've ever had a thyroid panel come back with a note like "TSH: 5.8 mIU/L — high" and no further explanation, you're not alone. Thyroid results are some of the most commonly misunderstood numbers on a standard blood report, partly because the thyroid affects almost everything — energy, weight, mood, cycles — and partly because "normal" isn't one fixed number.
What TSH actually measures
TSH (thyroid-stimulating hormone) isn't made by your thyroid — it's made by your pituitary gland, and its job is to tell your thyroid how hard to work. That's the part that trips people up: a high TSH usually means your thyroid is underactive (hypothyroid), because your pituitary is shouting louder to compensate.
TSH is your pituitary's request, not your thyroid's output. Read it as "how hard is my body asking my thyroid to work," not "how much thyroid hormone do I have."
Typical reference ranges
Ranges vary slightly by lab and method, but here's a general guide for non-pregnant adults:
| Marker | Typical range | Reflects |
|---|---|---|
| TSH | 0.4 – 4.0 mIU/L | Pituitary signal to the thyroid |
| Free T4 | 0.8 – 1.8 ng/dL | Main hormone the thyroid stores and releases |
| Free T3 | 2.3 – 4.2 pg/mL | Active hormone your cells actually use |
Why a borderline result isn't necessarily urgent
A TSH of 5.8 is above the typical upper bound, but "subclinical" hypothyroidism — a mildly elevated TSH with normal T4 — is common, often stable, and frequently just monitored rather than treated immediately. What matters more than the single number is the trend.
See this applied to your own report
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