Free thyroxine, the main thyroid hormone.
General health information, not a diagnosis. In an emergency, call 102. Always consult a qualified health professional.
Free thyroxine, the main thyroid hormone. Why it is done: With TSH to assess thyroid function. generated by SI from cited sources · general information, not a diagnosis · consult a health professional
Sources: SI (analytes, refranges, critical); LOINC; MedlinePlus Lab Tests (reference)
With TSH to assess thyroid function.
No fasting. Typical adult range: adults: 0.8 to 1.8 ng/dL (source: typical assay range, Mayo 0.9 to 1.7). Ranges vary by lab, age and sex; use the range on your report. High values may mean: Hyperthyroidism. Low values may mean: Hypothyroidism. General information, not a diagnosis. Results must be interpreted by a qualified health worker.
⚠️ Reference ranges vary by lab, age and sex — always use the range printed on your own report.
Consult a doctor to interpret results — a single test does not make a diagnosis.
Uses your location once to list the nearest facilities. Nothing is stored.
Why is Free T4 done?
With TSH to assess thyroid function.
Do I need to prepare or fast for Free T4?
No fasting. Typical adult range: adults: 0.8 to 1.8 ng/dL (source: typical assay range, Mayo 0.9 to 1.7). Ranges vary by lab, age and sex; use the range on your report. High values may mean: Hyperthyroidism. Low values may mean: Hypothyroidism. General information, not a diagnosis. Results must be interpreted by a qualified health worker.
This content includes LOINC® (loinc.org), © Regenstrief Institute, Inc. Used under the LOINC licence. (LOINC: 3024-7)
Sources: SI (analytes, refranges, critical); LOINC; MedlinePlus Lab Tests (reference)