T4 (Thyroxine) Test: What It Is, Function, Purpose & Levels
Oct 3, 2022 · A T4 (thyroxine) test is a blood test that helps diagnose thyroid conditions. Too much or too little T4 can indicate an issue with your thyroid.
T4 Blood Test: Purpose, Symptoms, High/Low Range - MedicineNet
Nov 5, 2025 · A T4 test examines thyroid function by measuring your blood level of the hormone T4 (thyroxine). Learn what symptoms lead up to a T4 test and what your results mean today.
Thyroid Function Tests | American Thyroid Association
Sep 5, 2023 · Tests measuring free T4 – either a free T4 (FT4) or free T4 index (FTI) – more accurately reflect how the thyroid gland is functioning when checked with a TSH. The finding of an elevated …
T4 Blood Test: What Is it Used For? - WebMD
Mar 16, 2024 · A T4 blood test measures your thyroxine hormone levels, which can show how well your thyroid is working. Low T4 levels are called hypothyroidism, and high T4 levels are called …
T4 Test: Purpose, Procedure, Abnormal Test Results & More
Oct 25, 2019 · Because T4 exists in two forms in your body, there are two kinds of T4 tests: a total T4 test and a free T4 test. A total T4 test measures the T4 that’s bonded to protein along...
Thyroxine (T4) Test - MedlinePlus
T4 levels can be measured with either a free T4 test or a total T4 test: A free T4 test measures the amount of free T4 in your blood. Medical experts believe this test is more accurate than a total T4 …
How to Read Your Thyroid Lab Results: TSH, T3, T4 Explained
Aug 4, 2025 · Free T4 provides accurate assessment of thyroid hormone availability. Low Free T4 with high TSH confirms primary hypothyroidism. Low Free T4 with normal/low TSH suggests central …
T4 Test: What It Tells You About Your Thyroid Health
Mar 31, 2025 · The T4 test helps assess thyroid function. Learn the types of T4 tests, why they're ordered, and what they can tell you.
T4 levels: What is a normal T4 level, and how it is tested?
Oct 23, 2023 · Combining a free T4 test with a TSH test gives the most accurate insight into how the thyroid is functioning. In adults, normal levels of total T4 range from 5–12 micrograms per deciliter...
T4 (thyroxine) Blood Test - Endocrine Surgery | UCLA Health
A T4 Thyroxine blood test measures levels of the T4 hormone, which is produced by the thyroid gland. Learn more about the T4 blood test & why T4 levels are important.