TSH (Thyroid Stimulating Hormone)
The pituitary-gland hormone used to screen for thyroid problems.
TSH tells your thyroid how much hormone to make. When the thyroid is underactive, TSH rises; when it's overactive, TSH falls. Most labs use a normal range of about 0.4-4.5 mIU/L, though some clinicians treat earlier in specific situations like pregnancy planning.
Medically reviewed by Dr. Ikechukwu Ogbu, MD
MD · Board-Certified, Internal Medicine · Last reviewed June 2026