First, it is important to know that we are born with all the hair cells we will ever have and there are about 5 million of them on the human body. The scalp will have the densest concentration of these hair cells. We cannot make more hair follicles so as our heads increase in size as we grow into adulthood, hair seems less “full” even if no hair loss occurs. Of course, with hair loss, the changes are even more noticeable.
The average head will hold about 100,000 hairs, though it varies by hair color. Blondes average 150,000, brown-haired people have 110,000, and redheads have about 90,000 scalp hairs. There will never be more. The good thing is that even if hair cannot multiply hair can regenerate. Every time a hair falls from your head or is found in a brush, another hair stands ready to take its place.
Nevertheless, once a hair follicle becomes too shrunken (miniaturized) by the effects of DHT, it becomes exceedingly unlikely that the hair-producing follicle will return to normal function. Totally bald spots will most often remain so. That is why so many young men are starting finasteride before hair loss has taken too heavy a toll.