T4, Free (Direct) Thyroxine
T4, Free (Direct) Thyroxine is a clinical biomarker on the Thyroid panel, reported in ng/dL. Standard reference range: 0.9–2.2 ng/dL. Functional (optimal) range used by integrative practitioners: 1–1.5 ng/dL.
What is T4, Free (Direct) Thyroxine?
Free T4 measures the unbound, biologically active form of thyroxine independent of TBG levels; it is the most accurate indicator of thyroid hormone availability to tissues.
Reference ranges
| Range type | Value (ng/dL) | Source |
|---|---|---|
| Standard (lab) | 0.9–2.2 | Typical Quest / LabCorp adult reference |
| Functional (optimal) | 1–1.5 | Integrative / functional medicine consensus |
How SomaVue interprets T4, Free (Direct) Thyroxine
SomaVue maps every result for T4, Free (Direct) Thyroxine against four clinical lenses — nutrient cofactors, toxin exposure, infection drivers, and circadian/hormonal context — and connects each interpretation to specific peer-reviewed citations. Pre-mapped clinical reasoning and cross-marker pattern detection are available inside the practitioner workspace.
See the full interpretation
Upload a patient PDF or enter values manually to see the four-lens analysis, cross-marker patterns, and cited evidence for T4, Free (Direct) Thyroxine and 205 other markers.
Try it freeEducational reference only. Reference ranges vary by laboratory, assay method, age, sex, and clinical context. Functional ranges represent integrative-medicine consensus and are not regulatory thresholds. SomaVue does not diagnose, treat, mitigate, or prevent disease. Always consult a licensed healthcare provider.