Free Testosterone Level (FTL) Calculator

Formula

The formula to calculate the free testosterone level (FTL) is:

\[ FTL = \frac{TT \times SHBG}{Albumin + SHBG} \]

Where:

\(FTL\) is the Free Testosterone Level
\(TT\) is the Total Testosterone
\(SHBG\) is the Sex Hormone Binding Globulin
\(Albumin\) is a protein that binds to testosterone

What is Free Testosterone Level?

A Free Testosterone Level is a medical test that measures the amount of testosterone (a male sex hormone) that is not bound to proteins in the blood. This is important because most testosterone is bound to sex hormone-binding globulin (SHBG) or albumin, and only a small portion is “free” or unbound. This free testosterone is biologically active and can affect the body’s tissues. The test is often used to diagnose sexual health issues in men, such as erectile dysfunction, infertility, or low sex drive, which may be caused by low testosterone levels.

Example Calculation

Let's assume the following values:

Total Testosterone (TT) = 500 ng/dL
Sex Hormone Binding Globulin (SHBG) = 30 nmol/L
Albumin = 4.5 g/dL

Using the formula to calculate the free testosterone level (FTL):

\[ FTL = \frac{TT \times SHBG}{Albumin + SHBG} = \frac{500 \times 30}{4.5 + 30} = \frac{15000}{34.5} \approx 434.78 \]

The Free Testosterone Level (FTL) is approximately 434.78.