TSH
The pituitary signal that regulates your thyroid — the first-line thyroid screen.
What is it
TSH is produced by the pituitary gland and signals the thyroid to produce thyroid hormones (T3 and T4). TSH is the most common thyroid screening test in clinical practice.
Why it's measured
TSH has been used as the foundational marker for evaluating thyroid function in research and clinical care. It typically moves before T3 and T4 when thyroid status changes.
Reference range
Standard laboratory reference
0.4 – 4.5 μIU/mL
Reference ranges vary by laboratory. Your individual reference range will appear on your test report and should be interpreted by your physician in the context of your overall health profile.
What results may indicate
Elevated
Has been associated with hypothyroidism in published research and warrants further evaluation.
Lower
Has been associated with hyperthyroidism in published research and warrants further evaluation.
These associations are general. They are not a personal diagnosis or prediction. Discuss your individual results with your physician in the context of your full health profile.
When it's measured
First-line thyroid screen in routine physicals and symptom evaluation.
Related markers
Measured in
A complete look at your heart, hormones, metabolism, inflammation, and longevity systems — drawn at Quest or LabCorp, reviewed by a U.S.-licensed physician.
Explore the Apex Panel →This information is for general educational purposes only and is not medical advice. Lab results alone are not intended to diagnose, treat, or cure any condition and do not replace the advice of a healthcare provider. OPTML does not offer medical advice, a diagnosis, medical treatment, or any form of medical opinion.