What do you mean by "Direct"? Do you mean from using total T, SHBG, and albumin with Vermeulen formula? Or do you mean RIA?
RIA is another world, maybe it has some meaning, but would need a conversion.
late answer, these numbers are actually available in the patent WO2014138026A1 - Methods and systems for the diagnosis and treatment of androgen disorders - Google Patents
for me, the main issue is that this algorithm is still a black box, which doesn't seem yet validated by the medical community.
ppi'd also like to see if there are some tools to compute the Zakharov free t which seems to provide pretty reliable results.