Thyroid function tests

Thyroid function tests, also called thyroid tests or thyroid symptom tests, show how well your thyroid gland is working. These tests are often used to diagnose an underactive (hypothyroidism) or overactive (hyperthyroidism) thyroid. Your provider may recommend them if you have a family history of thyroid disease or if you need monitoring after thyroid treatment, like medication, radioactive iodine therapy, or surgery.

At Penn Medicine, endocrinologists, radiologists, and lab specialists work together to provide accurate testing and clear explanations, so you know what your results mean and what comes next.

Your provider may recommend thyroid function testing if you have symptoms like fatigue, unexplained weight changes, hair loss, or rapid heartbeat. Because thyroid symptoms can have many causes, these tests are often the first step in finding out if your thyroid is the source of the problem. Your provider may also suggest testing if you have a family history of thyroid disease, have other autoimmune disorders, or have had previous radiation to the neck, even if you don’t have clear symptoms.

People already diagnosed with a thyroid condition may need regular testing to monitor their health. This regular testing helps your provider confirm that your medication and treatment are working effectively.

No recovery time is needed for most thyroid function tests. After testing, you can return to your usual activities right after a blood draw or imaging scan. If you have a nuclear medicine test, your care team may give you special instructions like drinking extra fluids to help clear the small amount of radioactive material from your body. 

When your results are ready, your provider will review them. If the tests show abnormal hormone levels, they may order additional tests to pinpoint the exact cause of the problem. Thyroid function tests provide important information that can help diagnose conditions like:

• Hyperthyroidism (overactive thyroid)
• Hypothyroidism (underactive thyroid)
• Thyroiditis
• Hashimoto’s disease
• Graves’ disease
• Postpartum thyroiditis

Having your thyroid function tested is only the first step. It’s just as important to have experts who can interpret the results and guide your care. At Penn Medicine, your testing is overseen by specialists in endocrinology, radiology, nuclear medicine, and pathology. We use advanced labs and imaging technology to give you accurate results, often within a short time. Our team also explains what your results mean and connects you to the right treatment if needed.