In an adult, the normal level of TSH is in the range of 0.4 to 4.2 milliunits per liter, states WebMD. The TSH test measures the quantity of thyroid-stimulating hormone that is manufactured and released by the pituitary gland into the blood. The test requires a blood sample.
A doctor may order this test when a patient has symptoms of either hypothyroidism or hyperthyroidism, explains the National Institute of Health. When the test shows that levels are significantly lower than the normal levels, it may be indicative of hyperthyroidism associated with a condition such as goiter, reports WebMD. Levels that are higher than the normal range may be hypothyroidism that is related to a medical condition like a pituitary gland tumor.