Parameters:
(1) serum albumin in g/L
(2) total serum testosterone in nmol/L
(3) sex steroid binding globulin (SSBG) in nmol/L
(4) association constant of testosterone for SSBG (1.4 * 10^9 L/mol)
N = (bioavailable testosterone) / (free testosterone) =
= 1 + ((1.4 * 10^9) * (albumin in g/L) / 69000) =
= 1 + (0.188 * (albumin in g/L))
a = (1.4 * 10^9) * N
b = N + ((1.4 * 10^9) * (10^(-9)) * ((SSBG) - (TT))) =
= N + (1.4 * ((SSBG) - (TT)))
c = ((-1) * (total testosterone) / (10^9)
calculated free testosterone =
= (10^9) * (((-1) * b) + SQRT((b^2) - (4 * a * c))) / (2*a)
calculated bioavailable testosterone =
= N * (calculated free testosterone)
