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What Are Normal TSH Levels?

Updated April 17, 2017

Your doctor may want to have your TSH level tested. The test will only take a few minutes, and your doctor can assist you with the results no matter what the outcome.

Reason For Test

TSH levels are checked if you show signs of hyperthyroidism or hypothyroidism. These conditions will be monitored with TSH tests, as well.

Test

TSH levels can be checked with a standard blood test. Blood is drawn from a vein using a syringe, and is then tested in a lab.

Normal TSH Levels

Normal TSH levels are between .4 and 4.0 mIU/L. If you have a thyroid condition, normal levels are between .5 and 3.0 mIU/L.

Low Levels

Low TSH levels may be caused by hyperthyroidism. TSH deficiency or use of certain medications may also be the culprit.

High Levels

Hypothyroidism or thyroid hormone resistance may cause high TSH levels. The cause could also be TSH-dependent hyperthyroidism.

References

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About the Author

Mike McQuillian began writing professionally for the Internet in 2005. He is an associate editor for YabYum Music, a local music Web site focusing on Arizona bands. He received his Bachelor of Arts in English literature from Arizona State University in 2005.