Equations of Ly and Handelsman for Estimating Free Testosterone from Total Testosterone and Sex Hormone Binding Globulin

 

Parameters:

(1) total testosterone in nmol/L

(2) sex hormone binding globulin in nmol/L

 

Equation if total testosterone is low (< 5 nmol/L)

 

estimated free testosterone in pmol/L =

= (19.9 * (total testosterone)) + (0.056 * (sex hormone binding globulin)) – (0.0959 * (total testosterone) * (sex hormone binding globulin)) – 6.593

 

Equation if total testosterone is high (>= 5 nmol/L)

 

estimated free testosterone in pmol/L =

= (24.4 * (total testosterone)) – (0.0584 * ((total testosterone)^2)) – (0.704 * (sex hormone binding globulin)) – (0.0782 * (total testosterone) * (sex hormone binding globulin)) – 52.65