Reference range 1
>= 0.4 – <= 4.8 µU/mL
- Population
- General
- Specimen
- Serum / plasma
Example reference interval
MedlinePlus example. TSH may vary by laboratory, time of day, and age.
Information about a laboratory test
TSH: What Does This Blood Test Measure?
Measures TSH, a pituitary hormone that signals the thyroid gland how much thyroid hormone to make.
Test summary
- Test name
- TSH
- Abbreviations
- TSH, Thyrotropin
- Category
- Endocrinology / Thyroid
- Panel
- Thyroid Function Tests
- Specimen
- Serum / plasma
- Common units
- mIU/L, µIU/mL
What does the test measure?
Measures TSH, a pituitary hormone that signals the thyroid gland how much thyroid hormone to make.
Why is the test ordered?
Commonly used as the first-line test for thyroid function, suspected hypo- or hyperthyroidism, and monitoring thyroid treatment.
Information about a low result
Low TSH may occur when thyroid hormone levels are excessive, but pituitary disorders, severe illness, and medicines can also affect it.
Information about a high result
High TSH may occur when thyroid hormone production is insufficient; age and treatment status can change interpretation.
Reference and clinical context
Use the reference interval printed on your own laboratory report first. Hormone results may vary with the assay, age, sex, pregnancy, menstrual-cycle phase, and sampling time.
Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.
Interpretation notes
TSH is usually interpreted with free T4. Pregnancy-specific reference intervals are preferred, and the upper range may be higher in advanced age.
Related specialties
- Endocrinology
- Internal Medicine
- Obstetrics and Gynecology
- Pediatric Endocrinology
Frequently asked questions
More information about this test
Sources
Thyroid Tests — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
U.S. government medical reference · 2026 · TSH, T4, T3 and thyroid-antibody testing; interpretation as a group · Verified: Aug 11, 2026
Hashimoto's Disease — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
U.S. government medical reference · 2026 · Hashimoto disease; TSH/T4/T3 and TPO antibody context · Verified: Aug 11, 2026
Graves' Disease — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
U.S. government medical reference · 2026 · Graves disease; thyroid-stimulating immunoglobulin / receptor-antibody context · Verified: Aug 11, 2026
TSH (Thyroid-stimulating hormone) Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2024 · TSH purpose; high/low context; effects of age, illness and medicines · Verified: Aug 11, 2026
TSH test — U.S. National Library of Medicine (MedlinePlus)
Government medical encyclopedia · 2026 · Example TSH reference interval; time-of-day and older-age caveats · Verified: Aug 11, 2026
Thyroxine (T4) Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2024 · Total/free T4 testing and thyroid-function context · Verified: Aug 12, 2026
Triiodothyronine (T3) Tests — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2023 · Total/free T3 testing and thyroid-function context · Verified: Aug 12, 2026
Thyroid Antibodies — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2023 · TPOAb, TgAb and TRAb; autoimmune-thyroid context · Verified: Aug 11, 2026
Thyroid Function Tests — American Thyroid Association
Professional society patient guidance · 2026 · TSH, free T4 and T3 interpretation; free vs total hormone context · Verified: Aug 11, 2026
Prolactin Levels — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2024 · Prolactin purpose; pregnancy, medicines and sampling-time context · Verified: Aug 11, 2026
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