Thyroid Stimulating Hormone (TSH) with Serum/Plasma Measurement by Immunoassay

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 working enough) or hyperthyroidism (when it’s working too much). It’s often the first test done to evaluate thyroid function, especially if you have symptoms like fatigue, weight changes, or unexplained issues with metabolism.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have fasting instructions depending on your doctor’s protocol, but generally, you can eat and drink normally. Bring any medications you’re taking, as some (like certain thyroid medications) can affect results.

What the Results Mean

TSH results can indicate whether your thyroid is producing too much or too little hormone. High TSH levels often suggest hypothyroidism, while very low levels may indicate hyperthyroidism. Your doctor will interpret results in relation to your symptoms and other tests.

Common Symptoms to Report

If you experience symptoms like unexplained weight changes, fatigue, hair loss, or changes in heart rate, mention them to your doctor before the test. These symptoms can sometimes signal thyroid imbalances that require further evaluation.