Thyroid Stimulating Hormone (TSH) with Serum/plasma Measurement

Why This Test Is Done

Your doctor may order a TSH test to check for thyroid problems, such as hypothyroidism (when your thyroid isn’t producing enough hormones) or hyperthyroidism (when it produces too much). It’s often the first test recommended when symptoms like fatigue, weight changes, or unexplained mood swings are present.

How the Test Works

A small blood sample is taken from a vein in your arm. The sample is sent to a lab, where it’s analyzed to measure TSH levels using an immunoassay method. This test helps determine whether your thyroid is functioning normally or if further evaluation is needed.

What to Expect Before the Test

No special preparation is usually required, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic or hormonal evaluation. Let your doctor know about any medications you’re taking, as some can affect TSH results.

What the Results Mean

Results are interpreted based on your symptoms and overall health. High TSH levels often suggest hypothyroidism, while very low levels may indicate hyperthyroidism. Your doctor will discuss the results with you and may recommend additional tests if needed.