Thyroxine free index
ChemistryAlso known as: FT4I SerPl Calc-mCnc{Index_val}
Calculates the level of active thyroid hormone (free T4) available in your bloodstream.
Normal Range
Consult your provider
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Abnormal Levels
Consult your provider
Specimen Type
Blood
Why This Biomarker Matters
Free T4 index provides a clearer assessment of thyroid function than total T4 alone, helping identify thyroid disorders that affect metabolism, energy, and weight.
Overview
The free T4 index is a calculated measure of thyroid hormone activity that estimates the amount of thyroxine (T4) available to affect your metabolism. Unlike total T4, it accounts for proteins that bind thyroid hormones, providing a more accurate picture of active thyroid hormone. This test helps evaluate thyroid function and diagnose hyperthyroidism or hypothyroidism when TSH alone may be unclear.
Technical Information (LOINC Codes)
Standardized laboratory codes for this biomarker
32215-6PrimaryThyroxine (T4) free index in Serum or Plasma by calculation
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Available Lab Tests
Order tests that measure this biomarker