Educational information from Her Form — reviewed for accuracy by our health specialists.
Not a substitute for personal medical advice. Optional 1:1 consults with Robyn, our consulting women's-health specialist, are available on request.
What it is
TSH rises when the brain wants the thyroid to make more hormone, and falls when there's enough. It's a sensitive but indirect marker — always pair with free T4 and free T3.
Why it matters for women
Thyroid problems disproportionately affect women and worsen around pregnancy and perimenopause. A TSH inside the lab range but above 2.5 often correlates with symptoms.
Optimal range
0.5–2.5 mIU/L.
Standard lab range
Lab ranges run 0.4–4.5.
When it's high
- ↑Hypothyroid: fatigue, weight gain, cold, hair loss, constipation, brain fog, low mood
When it's low
- ↓Hyperthyroid: palpitations, weight loss, anxiety, heat intolerance, insomnia
References
- American Thyroid Association (ATA) — Hypothyroidism guidelines— Full thyroid panel interpretation and treatment thresholds
- Endocrine Society — Thyroid function in women— Thyroid disorders in pregnancy and reproductive-age women
- NICE — Thyroid disease (NG145)— Assessment and management of thyroid disorders
- Jean Hailes — Thyroid health for women— Thyroid disease in perimenopause and pregnancy
References are provided for educational context only. Always interpret results with a qualified healthcare professional.
A note on interpretation. Ranges above are what our health specialists works to in healthy women. They are not a diagnosis — a single result always needs context from your symptoms, cycle phase and other markers.