Free T4 Index (T7)
What This Test Measures
Calculated value combining T3 uptake and Total T4; estimates free T4 without direct measurement.
Preparation
Many thyroid patients and functional practitioners target Free T4 in the middle-to-upper half of the reference range, rather than anywhere 'in range.' A low-normal Free T4 combined with low-normal Free T3 is considered suboptimal by functional practitioners even if TSH is 'normal.'
Reflects common practices in thyroid, BHRT, and functional medicine communities. This may differ from standard clinical guidelines. Not medical advice — always discuss with your provider.
General guidelines only. Requirements vary by lab and individual. Confirm with your provider before adjusting any medications.
Turnaround Time
Varies by lab
Clinical Notes
Panel code; increasingly replaced by direct Free T4
ICD-10 Codes
Common diagnosis codes associated with this test. Codes are assigned by your provider.
Self-Pay Pricing
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Uses Quest Diagnostics network; generally lowest DTC prices; not available in NY, NJ, RI
Uses both Quest and Labcorp networks; competitive pricing; broad test selection
Uses Labcorp network; known for supplement company; competitive lab test pricing
Uses Quest and Labcorp; strong panel bundling; results in 1-3 days
Uses Quest and Labcorp networks; offers both individual tests and discounted panels
Lab Codes
Proprietary codes used by each lab for this test.
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For informational purposes only
This page is for educational and research purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. ICD-10 and CPT codes are assigned by your healthcare provider. Always consult a qualified healthcare provider before ordering any lab test or making decisions about your health.