Vermeulen free testosterone estimate

Calculates free and non-SHBG-bound fractions from total testosterone, SHBG and albumin.

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Calculation

Total testosterone — Units

Enter measured albumin. The initial 43 g/L is an example, not your laboratory result.

The result updates as you change the fields. Your data never leaves the browser.

This calculation is for reference only and is not medical advice, a diagnosis or a prescription. If you have a medical condition, are pregnant, take medication or have any doubts, discuss the result with a physician or a qualified nutrition professional.

Result

Free testosterone
0.298 nmol/L (85.8 pg/mL)

This is calculated, not directly measured. No universal normal range is set: interpretation depends on symptoms, age, sex, assay and repeat measurements.

Free fraction
1.98 %

This is calculated, not directly measured. No universal normal range is set: interpretation depends on symptoms, age, sex, assay and repeat measurements.

Bioavailable testosterone
6.97 nmol/L (46.5 %)

This is calculated, not directly measured. No universal normal range is set: interpretation depends on symptoms, age, sex, assay and repeat measurements.

Total testosterone
15.00 nmol/L (432 ng/dL)

This is calculated, not directly measured. No universal normal range is set: interpretation depends on symptoms, age, sex, assay and repeat measurements. Compare with laboratory references and discuss with a professional; this value alone does not establish hypogonadism. Reference ranges are population benchmarks from the cited sources. Laboratories use their own ranges, and interpretation depends on clinical context: discuss the result with your physician.

How it is calculated

Vermeulen (1999) equilibrium binding model: K_SHBG=10⁹ L/mol, K_Alb=3.6×10⁴ L/mol, albumin molecular weight 69,000 g/mol. Modelled bioavailable testosterone is free plus albumin-bound testosterone.

Formula

Vermeulen (1999) equilibrium binding model: K_SHBG=10⁹ L/mol, K_Alb=3.6×10⁴ L/mol, albumin molecular weight 69,000 g/mol. Modelled bioavailable testosterone is free plus albumin-bound testosterone.

Limits of the method

This is calculated, not directly measured. No universal normal range is set: interpretation depends on symptoms, age, sex, assay and repeat measurements.

Sources of the method

How to use the calculation

1

Enter the starting values

Use actual values and the appropriate units.

2

Adjust the parameters

Adjust the starting assumptions for your situation.

3

Read the result

Consider the model limitations; a calculation is not a measurement.

Frequently asked questions

What does the calculation show?

Calculates free and non-SHBG-bound fractions from total testosterone, SHBG and albumin. Vermeulen (1999) equilibrium binding model: K_SHBG=10⁹ L/mol, K_Alb=3.6×10⁴ L/mol, albumin molecular weight 69,000 g/mol. Modelled bioavailable testosterone is free plus albumin-bound testosterone.

What limitations apply?

This is calculated, not directly measured. No universal normal range is set: interpretation depends on symptoms, age, sex, assay and repeat measurements. Compare with laboratory references and discuss with a professional; this value alone does not establish hypogonadism.

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