$4.00
Priced per marker, with baseline labs included. You’ll see your total before you pay.
Thyroid
TSH with reflex to free T4 test
TSH with automatic Free T4 if TSH is abnormal — efficient thyroid screening.
At a glance
In about 5 days
Most results are ready in about 5 days. Some specialty markers can take up to 21 days.
May have a step to take first. Contact us to ask
Contact us before your draw if you’re not sure.
Walk in at Quest
Your lab order arrives by email. Most Quest locations take walk-ins, so bring it with a photo ID.
What it measures
TSH, or thyroid-stimulating hormone, tells your thyroid how hard to work. If your TSH is outside the normal range, the lab automatically adds free T4, the thyroid’s main hormone, to help explain why.
Why it matters for women
Thyroid conditions are much more common in women and can show up after having a baby or in midlife. This approach screens with TSH and adds free T4 only when needed. In pregnancy, normal TSH can run a bit lower, so results are compared with pregnancy ranges.
You might check it if…
- you feel tired, cold or foggy more than usual
- you’re planning a pregnancy
- you had a baby in the past year
- thyroid disease runs in your family
What your result may mean
High TSH with reflex to free T4: what it may mean
High TSH may point to an underactive thyroid (hypothyroidism), because the pituitary gland can push harder when thyroid hormone runs short. On this test, a high TSH can trigger an added free T4 to help measure how much the thyroid is lagging. It can happen with Hashimoto's thyroiditis, thyroid changes after having a baby (postpartum thyroiditis), too little thyroid medicine, or medicines such as lithium or amiodarone. Some people may notice tiredness, feeling cold, constipation, weight gain or heavier periods, and others may have no symptoms. In pregnancy, a clinician may compare TSH with pregnancy ranges.
Low TSH with reflex to free T4: what it may mean
Low TSH may point to an overactive thyroid (hyperthyroidism), and on this test it can trigger an added free T4 to help gauge how severe that is. It can happen with Graves' disease, thyroid nodules, thyroiditis, or too much thyroid medicine. Normal TSH can run a bit lower in early pregnancy, so results may be compared with pregnancy ranges. Some people may notice a racing heart, shakiness, weight loss, feeling hot or lighter periods, and others may feel fine. High-dose biotin can make TSH read falsely low on some lab tests, and steroid medicines or serious illness can lower it too.
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These notes provide context and do not diagnose a condition. Not yet available in NY, NJ, RI, HI, ND, SD or WV.