Free Triiodothyronine (T₃) with Triple Bolus Thyroid Stimulating Hormone (TSH) Test
This test measures free thyroid hormone (T₃) and thyroid-stimulating hormone (TSH) to help assess thyroid function, especially in cases where standard tests may not be sufficient.
Evaluates thyroid hormone balance and potential subclinical thyroid issues.
Key facts at a glance
- LOINC
- 40328-7
- Short code
- T3Free 2h p Triple Bolus SerPl-sCnc
- Synonyms
- T3Free 2h p Triple Bolus SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 80
- Ref high
- 200
- Critical range
- 20 N/A – 400 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85610
- SNOMED
- 396252006
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your doctor may recommend this test if you have symptoms like fatigue, weight changes, or unexplained thyroid dysfunction, or if standard TSH tests show borderline results. It can also help diagnose conditions like subclinical hypothyroidism or hyperthyroidism where other tests are inconclusive.
What to Expect Before the Test
No special preparation is needed for this test. Blood is drawn from a vein, usually in your arm. You may feel a slight pinch, but it typically takes a few minutes to complete. Avoid caffeine or alcohol before the test if instructed by your healthcare provider.
What the Test Measures
Free T₃ measures the active form of thyroid hormone circulating in your blood. TSH is a hormone produced by your pituitary gland to regulate thyroid function. This combination helps determine if your thyroid is producing too much or too little hormone.
Common Reasons for Abnormal Results
Abnormal results may indicate thyroid disorders such as hyperthyroidism (overactive thyroid), hypothyroidism (underactive thyroid), or conditions affecting thyroid hormone metabolism. It can also help identify thyroiditis or other thyroid-related conditions.
Reference range
Adult: 80-200 ng/dLN/A
Take your thyroid medication after the blood draw if applicable. No fasting required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
T₃-Free TSH Profile
Frequently asked questions
What causes this test to be ordered?
How long will it take to get results?
Can I take anything before the blood draw?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy