Reverse T3 Ratio Calculator

Formula

The formula to calculate the Reverse T3 Ratio (RTR) is:

\[ RTR = \left( \frac{FT3}{rT3} \right) \times 100 \]

Where:

\( RTR \) is the Reverse T3 Ratio (%).
\( FT3 \) is the Free T3 Level (pg/mL).
\( rT3 \) is the Reverse T3 Level (ng/dL).

What is a Reverse T3 Ratio?

A Reverse T3 Ratio is a measure used in the field of endocrinology to assess thyroid function. It involves comparing the levels of Reverse T3 (RT3), an inactive form of the thyroid hormone, to the levels of Free T3 (FT3), the active form of the hormone. A high RT3 ratio may indicate a condition known as Reverse T3 Dominance, where the body is producing too much RT3 and not enough FT3, leading to symptoms of hypothyroidism despite normal thyroid-stimulating hormone (TSH) levels.

Example Calculation

Consider an example where:

Free T3 Level (FT3): 3.5 pg/mL
Reverse T3 Level (rT3): 0.25 ng/dL

Using the formula to calculate the Reverse T3 Ratio:

\[ RTR = \left( \frac{3.5}{0.25} \right) \times 100 = 1400 \% \]

This means that the Reverse T3 Ratio for this example is 1400%.