The Bioavailable Testosterone Calculator is a specialized tool designed to estimate the levels of bioavailable and free testosterone in the bloodstream. Unlike total testosterone levels, which include testosterone bound to proteins in the blood (such as sex hormone-binding globulin, or SHBG), bioavailable testosterone calculates the fraction of testosterone that is not bound and is readily available to tissues. This distinction is crucial, as it is the bioavailable or free testosterone that is biologically active and can exert effects on the body.
Formula of Bioavailable Testosterone Calculator
To grasp how the calculator operates, it’s essential to understand the formulas it uses. These mathematical models allow healthcare professionals and individuals to estimate testosterone levels accurately without direct measurement.
For Free Testosterone (FT) estimation:
FT (nmol/L) = Total Testosterone (nmol/L) / ( SHBG (nmol/L) * constant + 1)
Where:
Total Testosteroneis the total testosterone level in nanomoles per liter (nmol/L).SHBGis the sex hormone-binding globulin level in nanomoles per liter (nmol/L).- The
constantis a value determined by the specific units used in the formula.
For Bioavailable Testosterone (Bio T) estimation:
Bio T (nmol/L) = e^( -0.266 + 0.955 * ln(Total Testosterone (nmol/L)) – 0.228 * ln(SHBG (nmol/L)) )
Where:
Total Testosteroneis the total testosterone level in nanomoles per liter (nmol/L).SHBGis the sex hormone-binding globulin level in nanomoles per liter (nmol/L).lndenotes the natural logarithm function.
General Terms and Quick Reference Table
| Total Testosterone (nmol/L) | SHBG (nmol/L) | Hypothetical Free Testosterone Estimate (nmol/L) | Hypothetical Bioavailable Testosterone Estimate (nmol/L) |
|---|---|---|---|
| 10 | 20 | 0.48 | 3.5 |
| 15 | 25 | 0.57 | 5.2 |
| 20 | 30 | 0.64 | 7.0 |
| 25 | 35 | 0.70 | 8.9 |
| 30 | 40 | 0.75 | 10.7 |
Key Assumptions for Hypothetical Estimates:
- The “Hypothetical Free Testosterone Estimate” assumes a constant value that has been simplified for these calculations. In real scenarios, this constant can vary, affecting the final estimate.
Example of Bioavailable Testosterone Calculator
Let’s consider an example to illustrate the application of these formulas. Suppose a person has a total testosterone level of 20 nmol/L and an SHBG level of 40 nmol/L. Using the formula for Free Testosterone (FT):
FT = 20 / (40 * constant + 1)
Assuming the constant is appropriately chosen base on the measurement units. This formula will yield the free testosterone level.
For Bioavailable Testosterone (Bio T), using the given values:
Bio T = e^( -0.266 + 0.955 * ln(20) – 0.228 * ln(40) )
This calculation will estimate the bioavailable testosterone level, offering insights into the hormone’s active portion in the body.
Most Common FAQs
Total testosterone includes all testosterone in the bloodstream, both free and bound. Free testosterone refers to testosterone not bound to proteins, while bioavailable testosterone includes free testosterone and testosterone loosely bound to albumin, both of which are available for use by the body.
It varies depending on individual health conditions, but generally, if you’re undergoing testosterone therapy or have symptoms of testosterone imbalance, your healthcare provider might recommend regular testing.
While the Bioavailable Testosterone Calculator provides valuable estimates, it should not replace professional medical advice. Always consult healthcare providers for diagnosis and treatment decisions.