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Thyroxine (Total T4) Unit Converter
Total Thyroxine (T4) is the major hormone secreted by the thyroid gland. In the bloodstream, the majority of T4 is bound to transport proteins (TBG, transthyretin, and albumin). Total T4 measures both the free (active) hormone and the bound portion.
Clinically, Total T4 is used alongside TSH to screen for thyroid disorders. Abnormal levels of binding proteins (e.g., in pregnancy or liver disease) can alter Total T4 levels without changing the patient’s true metabolic status. This converter facilitates switching between the standard mass units (μg/dL) and SI molar units (nmol/L).
Mass Units (US)
StandardMicrograms per deciliter (Most common US unit).
SI Units / Molar
Nanomoles per liter (International Standard).
Clinical Context
Reference Ranges (Adults):
• Conventional: 4.5 – 11.2 μg/dL.
• SI: 58 – 144 nmol/L.
Interpretation:
• High Total T4: Hyperthyroidism, or high TBG (e.g., pregnancy, estrogens).
• Low Total T4: Hypothyroidism, or low TBG (e.g., nephrotic syndrome, androgens).
Conversion Logic:
Molecular Weight of T4: ~776.87 g/mol.
1 μg/dL ≈ 12.87 nmol/L.
1 nmol/L ≈ 0.0777 μg/dL.
Clinical References
How to Use This Converter
Follow these steps to normalize Total T4 values.
Enter Values
Input your laboratory result into the corresponding unit field (e.g., μg/dL).
Automatic Conversion
The calculator converts between mass units and the SI molar unit using the molecular weight of 776.87 g/mol.
Reset
Use the Clear button to reset all fields.
Frequently Asked Questions
Total T4 measures all T4 in the blood (bound + free). Free T4 measures only the unbound, active fraction. Free T4 is generally preferred because it is not affected by protein levels.
Yes. A deciliter (dL) is 100 milliliters (mL).