Total testosterone is likely the best measure for assessing testosterone's impact on cells and brain and ensuring it is not overly toxic.

“but the most important reason for monitoring blood levels and I monitor for because of what you explained the smartest thing is just to men a total te right it's not a so we we didn't go through this in elaborate detail it's not clear that that's the best marker for knowing whether that's the way to tell whether testosterone is helping a patient in their cells and in their brain right their genital cells their brain and some other body cells too right but that's probably the grossest best measure we have because T fre is calculated and we don't even know if that's the bioactive component yeah testosterone it's a very complex what now is called iny it hits the cells it gets converted into metabolites um Androgen DHT it enters the cell through the Androgen receptor and has both genomic and non- genomic effects non-genomic means direct action genomic means it causes Gene translation other protein development which then has trophic effects right and so all of that's happening”