Advanced Free Testosterone and Bioavailable Testosterone Calculator

Author: Neo Huang Review By: Nancy Deng
LAST UPDATED: 2024-12-09 09:13:04 TOTAL USAGE: 2285 TAG: Biology Health Testosterone

Unit Converter ▲

Unit Converter ▼

From: To:
Powered by @Calculator Ultra

Find More Calculator

Historical Background

Free testosterone and bioavailable testosterone are critical indicators of hormonal health, particularly in diagnosing conditions such as hypogonadism. These calculations are based on biochemical principles, integrating albumin and SHBG levels to derive free testosterone, bioavailable testosterone, and Free Androgen Index (FAI).

Calculation Formula

  1. Free Testosterone (ng/dL):
    \[ T_{\text{free}} = \frac{T_{\text{total}} - N - S + \sqrt{(N + S - T_{\text{total}})^2 + 4NT_{\text{total}}}}{2N} \]
    Where:

    • \( N = 0.5217 \times \text{Albumin} + 1 \)
    • \( S = \text{SHBG} \)
  2. Bioavailable Testosterone (ng/dL):
    \[ T_{\text{bioavailable}} = N \times T_{\text{free}} \]

  3. Free Androgen Index (FAI):
    \[ FAI = \frac{T_{\text{total}} \times 100}{S} \]

Example Calculation

If:

  • Total Testosterone = 600 ng/dL
  • SHBG = 40 nmol/L
  • Albumin = 4.3 g/dL

\[ N = 0.5217 \times 4.3 + 1 = 3.2433
\]

\[ S = 40
\]

\[ T_{\text{free}} = \frac{600 - 3.2433 - 40 + \sqrt{(3.2433 + 40 - 600)^2 + 4 \times 3.2433 \times 600}}{2 \times 3.2433} = 11.1 \, \text{ng/dL}
\]

\[ T_{\text{bioavailable}} = 3.2433 \times 11.1 = 36.0 \, \text{ng/dL}
\]

\[ FAI = \frac{600 \times 100}{40} = 150
\]

Importance and Usage Scenarios

This calculator is vital for healthcare professionals and patients to evaluate hormonal imbalances, optimize treatment strategies, and track hormonal health over time.

Common FAQs

  1. What is bioavailable testosterone?

    • Bioavailable testosterone is the portion of testosterone that is either free or weakly bound to albumin, making it accessible for biological functions.
  2. What is the Free Androgen Index (FAI)?

    • FAI is a ratio used to estimate the amount of active testosterone in the blood, calculated from total testosterone and SHBG levels.
  3. Why are SHBG and albumin included in these calculations?

    • SHBG binds to testosterone, reducing its activity, while albumin binds weakly and allows bioavailability. These factors are critical for accurate assessments of free and bioavailable testosterone.

This advanced calculator supports precise hormone analysis, empowering healthcare decisions.

Recommend