1. What Is T4 (Thyroxine)?

T4 (thyroxine) is a hormone produced by the thyroid gland that plays a crucial role in regulating metabolism, growth, and development. It exists in both free and bound forms in the bloodstream and is commonly measured to assess thyroid function.

2. Understanding The Conversion

The conversion between nmol/L and ng/dL for T4 is based on the molecular weight of thyroxine (776.87 g/mol):

Where:

• nmol/L — Nanomoles per liter (SI unit)
• ng/dL — Nanograms per deciliter (conventional unit)
• 0.776 — Conversion factor derived from molecular weight

Explanation: The conversion factor accounts for the difference in molecular mass measurement units between the International System (SI) and conventional units.

3. Importance Of Unit Conversion

Details: Accurate unit conversion is essential for proper interpretation of thyroid function tests, especially when comparing results from different laboratories or following international treatment guidelines that may use different measurement units.

4. Using The Calculator

Tips: Enter the T4 value in nmol/L. The calculator will automatically convert it to ng/dL using the standard conversion factor of 0.776. Ensure the input value is positive and valid.

5. Frequently Asked Questions (FAQ)

Q1: Why are there different units for measuring T4?
A: Different countries and laboratories use different measurement systems. The SI unit (nmol/L) is used in most countries, while conventional units (ng/dL) are still used in some regions, particularly the United States.

Q2: What is the normal range for T4 levels?
A: Normal T4 ranges vary by laboratory but typically fall between 5.0-12.0 μg/dL (64-154 nmol/L) for total T4 and 0.8-2.0 ng/dL (10-26 pmol/L) for free T4.

Q3: Does this conversion apply to both total and free T4?
A: This specific conversion factor (0.776) applies to total T4 measurements. Free T4 conversions use a different factor due to differences in molecular weight considerations.

Q4: How accurate is this conversion?
A: The conversion is mathematically precise based on the molecular weight of thyroxine. However, always verify with your healthcare provider as reference ranges may vary between laboratories.

Q5: When should T4 levels be tested?
A: T4 testing is typically done when thyroid disorders are suspected, to monitor thyroid replacement therapy, or as part of routine thyroid function screening in at-risk populations.