Thyroid Stimulating Hormone (TSH) with Serum/Plasma Measurement

Why This Test Is Done

Your doctor may order a TSH test to diagnose or monitor thyroid disorders, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). It’s often the first test for thyroid issues because it’s sensitive and easy to perform. TSH levels can also be checked during pregnancy, before starting certain medications, or if you have symptoms like fatigue, weight changes, or unexplained mood swings.

What to Expect Before the Test

No special preparation is usually needed, but your doctor might ask you to avoid certain medications (like thyroid hormone replacements) for a few days before testing. If you’re pregnant or breastfeeding, let your healthcare provider know. You’ll typically have a small needle inserted into your arm or a blood sample drawn from your hand or finger.

What the Results Mean

TSH results help determine whether your thyroid is producing too much or too little hormone. High TSH levels often indicate hypothyroidism, while very low levels may suggest hyperthyroidism. Your doctor will compare your results to your symptoms and other tests to make a diagnosis.

Common Symptoms to Watch For

If your TSH levels are abnormal, you might experience symptoms like unexplained fatigue, weight changes (gain or loss), dry skin, hair loss, or depression. Always discuss any symptoms with your doctor, as thyroid issues can affect many parts of your body.