Thyroid Stimulating Hormone (TSH)
- Sample Type
- Standard
- Fasting
- No
- Unit
- mIU/L
TSH is produced by the anterior pituitary gland to regulate the production of T4 and T3 by the thyroid gland. It is the most sensitive first-line screen for thyroid dysfunction because of the inverse logarithmic relationship between TSH and free thyroid hormones. In a Thyroid Function Panel, it determines whether the thyroid is overactive, underactive, or if the issue lies within the pituitary/hypothalamic feedback loop.
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Enter your lab result to see where you stand compared to the standard reference range.
Why Context Matters
The 'normal' range is controversial; many experts argue for a narrower range (0.3–2.5 mIU/L). Furthermore, Biotin supplements can cause falsely low TSH results in certain lab assays. TSH also follows a diurnal rhythm, peaking at night and reaching its nadir in the late afternoon, which can lead to misinterpretation if not standardized.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Clinical References
Source-of-truth databases and clinical guidelines for Thyroid Stimulating Hormone (TSH):
Official Sources
- TSH test: MedlinePlus Medical EncyclopediaMedlinePlus
Research & Guidelines
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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