T3 Uptake Test
The T3 uptake test measures the available thyroid hormone binding sites in a blood sample. It is not read on its own; results are meant to be interpreted together with thyroxine (T4) levels.
About this test
T3 uptake, also called T3 resin uptake or T3RU, measures how much room is left on thyroid hormone binding proteins in the blood. Quest lists it under several names, including T3 Index and Hanolsky Uptake Test, all referring to this same serum measurement, produced using immunoassay methodology.
The result by itself does not describe thyroid function. Quest notes that levels can be decreased in association with pregnancy, estrogen use, hyperproteinemia or acute intermittent porphyria, and increased in association with androgen use, hyperproteinemia, stress or acute liver disease, which is one reason this test is intended to be interpreted together with a T4 measurement rather than as a standalone result.
Who might consider this test?
- Certain liver or protein conditions can shift the result
- The reason for testing and a person's broader health picture shape how a clinician reads it
Test details
| Quest code | 861 |
|---|---|
| Methodology | Immunoassay |
| Sample type | 1 mL serum |
| Collection | Quest patient service center |
Reference range
22-35 %
Reference ranges are general guidance. The range printed on your own laboratory report is the one that applies to your result.
Related tests and panels
Quest resources
Additional details
What this test looks at
The test reports a single value describing thyroid hormone binding sites available in the serum sample. Quest lists this test under several names, including T3 resin uptake, T3RU, T3 Index and Hanolsky Uptake Test, and they all refer to the same immunoassay measurement.
How it's often used alongside other tests
Because Quest describes this result as intended for interpretation together with thyroxine (T4) levels, it is typically ordered alongside a T4 test rather than by itself. A clinician weighs the two results together, along with any of the factors — such as pregnancy, hormone use, or liver disease — that Quest lists as capable of raising or lowering the T3 uptake value.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does the T3 uptake test measure?
It measures the available thyroid hormone binding sites in a blood serum sample, using immunoassay methodology. The result is intended to be read together with a thyroxine (T4) level rather than on its own.
How is the T3 uptake sample collected?
The test uses a serum sample from a routine blood draw at a Quest Diagnostics patient service center.
Do I need to prepare for a T3 uptake test?
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.
Why is T3 uptake read together with a T4 test?
Quest describes the T3 uptake result as intended to be interpreted alongside thyroxine (T4) levels rather than as a standalone result, because the value can be influenced by more than one physiological factor.
What can affect a T3 uptake result?
Quest notes that levels may be decreased in association with pregnancy, estrogen use, hyperproteinemia, or acute intermittent porphyria, and increased in association with androgen use, hyperproteinemia, stress, or acute liver disease.
How much does the T-3 Uptake test cost?
The cash price at Celio Health is $35. That covers the physician's order and sample collection at a Quest patient service center — no insurance is needed and there's no separate doctor's visit to pay for.