What is Total Testosterone?

The count includes hormone bound to carrier proteins and hormone travelling free, so it reports what the gonads have made rather than what tissues receive. That makes it the figure to read when the question is whether production itself has changed.

LH is the pituitary signal that stimulates the gonadal cells making testosterone, so reading LH alongside the total places a change in production either at the pituitary or at the gonads themselves. SHBG is the protein that binds most of the hormone and Free Testosterone estimates the share left unbound, and either can move while the total stays where it is.

The capacity of the testes or ovaries sets the underlying rate of production, and that capacity declines gradually with age. On top of that rate, release follows a daily rhythm, highest in the early morning and declining through the day.

A morning reading cannot be compared with an afternoon one. Output from the testes or ovaries shifts over weeks and months, and a year's spacing is set to that slower movement. Two samples a year apart are both drawn in the early morning, so what they compare is production rather than the hour. This is Do Health's monitoring schedule, not a general recommendation for everyone.