There's nothing unusual about that free T percentage with an SHBG of 27 nmol/L. Free T may have been calculated via either the Vermeulen method or the multi-ligand method, as both are close to that 2.3% figure.
As for the "variability in the stickiness of SHBG," though possible, substantial variations may be uncommon. And in any case, clearly calculated free T cannot be used as supporting evidence, nor can one use the notoriously inaccurate direct free T tests. Instead free T must be measured via equilibrium dialysis or possibly ultrafiltration.
