TSH Health Article

Normal Values

Normal values are 0.4 - 4.0 mIU/L.

However, those without signs or symptoms of an underactive thyroid who have a TSH value over 2.0 mIU/L but normal T4 levels may develop hypothyroidism in the future. This is called subclinical hypothyroidism (mildly underactive thyroid) or early-stage hypothyroidism. Anyone with a TSH value above this level should be followed very closely by a doctor.

If you are being treated for a thyroid disorder, your TSH level should be between 0.5 and 3.0 mIU/L.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Greater than normal levels may indicate:

• Congenital hypothyroidism (cretinism)
• Exposure to mice (lab workers or veterinarians)
• Primary hypothyroidism
• Thyroid hormone resistance
• TSH-dependent hyperthyroidism

Lower than normal levels may be due to:

• Hyperthyroidism
• TSH deficiency
• Use of certain medications (including dopamine agonists, glucocorticoids, somatostatin analogues, and bexarotene)

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated wit having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

References

AACE Thyroid Task Force. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism. Endocr Pract. 2002;8(6):457-469.