When one experiences androgenetic alopecia then the hair starts to miniaturize and will eventually disappear along with the roots. It is difficult to gauge the loss of hair as one would only begin to notice the same after a considerable density of hair is gone. It is better to visit a dermatologist and get a proper evaluation of the same.
Under the normal hair fall cycle, the hair follicles fall off but the roots are intact. The new follicles grow back in the anagen phase and stay stagnant during the catagen phase after the telogen phase is over.