evildude said:
Hey Dr. Proctor.
Does that mean everyone will shed at least a little bit, but most people won't notice it?
Furthermore, i read a post on another forum, in which you said that hairs in the "resting phase" are sometimes shed as a result of taking a hair growth promotor(or finasteride). You said something along the lines of that new "hair production" began and so the chemical binding of the old hair was cut. This all makes sense, but my question is this. Does this only apply to hairs in the resting phase? What about miniaturized hairs that are still growing? Hairs that are "damaged", but not yet entered the resting phase? Will they be unafected by the hair growth stimulator? Will they eventually be affected once they enter the resting phase?
Lots of questions. Hope you have the time to answer.
Dr P replies:
1) I suspect that a few hairs are shed early in most persons on medical treatment. But not enough that this is generally noticible in terms of an increased loss rate.
2) The very last part of the telogen phase involves the hair moving to the top of the follicle and enzymatically-dissolving the molecular bonds (desmosomes) that attach it to the follicle. This is where you get all those hairs that come out with a light pull. In the anagen (growth), catagen, and early telogen phases, the molecular bonds are still pretty strong. In fact, so strong that the hair typically breaks off rather than pulling out.
This can have practical importance-- I once testified in a murder case that a hair found grasped in the hand of the murder victim was broken traumatically (obvious under the microscope). Thus it was likely from his attacker, not just a shed hair that wandered into the scene.
3) As for vellous hairs-- the same. The difference is that vellous hairs may only spend only 3-6 months or so in the growth phase. Then the standard 2-4 months in the telogen (loss) phase. I.e., About half of your vellous hair is in the loss phase at any one time. Ya cut the length of the loss phase with treatment and it can seem as though vellous hair is coming out in handfulls. Relax, the hair that replaces it is likely to be longer and coarser with each succeeding hair cycle.
4) Very often, the first response to treatment is vellous hair. A common complaint on medical treatment is "Early-on, I grew a bunch of short fine hair. then it all fell out at six months". Treatment has not stopped working. It is just that this vellous hair has gone thru its cycle, shortened by the effect of medical treatment on the loss-phase. Again, the hair that replaces it is likely to be coarsere and longer and will spend more time in the growth phase.
The unfair thing is this typically happens in people who responded early and well to treatment, which gets the new vellous growth synchronized and hopes raised. Then it all seems to fall out at once, dashing hopes. Again, this is an artifact of the way medical treatment interacts with the hair cycle and is actually a sign of a reasonable response.
Peter H. Proctor, PhD,MD