TSH (Thyroid Stimulating Hormone) Blood Test
TSH is the brain's signal to your thyroid — and the most useful single number for screening thyroid function.
What TSH measures
TSH (thyroid stimulating hormone) is produced by the pituitary gland in your brain. It tells your thyroid how much hormone to make. When thyroid hormone levels drop, TSH rises to push the thyroid harder. When thyroid hormone levels rise, TSH drops. That inverse relationship makes TSH a sensitive early signal — it can move before T4 and T3 levels do.
Who should consider checking TSH
Have you noticed any of these:
- fatigue or low energy
- unexplained weight changes
- feeling cold or warm all the time
- brittle nails or thinning hair
- irregular periods or fertility questions
- anxiety, brain fog or low mood
How the test works
Single blood draw, no fasting required. Most consistent first thing in the morning. Results back same day.
What "normal" can look like
Australian labs commonly use a reference range of roughly 0.4–4.0 mIU/L. The optimal-feeling range is often discussed by thyroid-focused practitioners as a tighter window. Results outside (or near the edge of) the lab range warrant a conversation with your doctor — context matters: TSH varies with time of day, season, stress and life stage. We provide information; your doctor provides interpretation.
Where to get a TSH test
TSH is included in these panels:
- Thyroid Check (TSH + Free T4) — The standard two-marker thyroid function screen. TSH, the brain's signal to the thyroid, and Free T4, the hormone it produces in response. Read together, they give a useful first picture of how your thyroid is working. A$89
- Thyroid + Antibodies Panel — The full thyroid picture — both how your thyroid is working and whether your immune system is involved. A$169
- Core Health Panel — The full check — 42 biomarkers across 8 health areas, in one blood test. Our most comprehensive panel. A$329
Frequently asked questions
Do I need to fast for a TSH test?
No. Thyroid hormones don't require fasting.
I'm on thyroid medication — when should I test?
Most people test before their morning dose for consistency. Talk to your doctor about meaningful timing.
Is high TSH bad?
High TSH usually means your thyroid isn't producing enough hormone — your pituitary is asking for more. The clinical interpretation depends on how high, your age and sex, and what other markers (like Free T4 and antibodies) show. Discuss any out-of-range result with your doctor.
Why does TSH change?
TSH drifts naturally with stress, illness, sleep loss, time of day, and pregnancy. A single elevated TSH isn't a diagnosis — patterns matter more than one number.
Related biomarkers
Guides
- Can You Get a Blood Test in Australia Without a GP Referral? (2026) — Yes — most common blood tests can be self-ordered in Australia. How direct-to-consumer pathology works, what's available, and when you should still see a GP first.
- How Much Does a Private Blood Test Cost in Australia? A Buyer's Guide (2026) — Private blood tests in Australia range from $35 for single biomarkers up to $500+ for comprehensive panels. What you're paying for, what drives the cost, and when private testing is worth it.