Normal daily shedding of hair: Does it occur equally?

Does normal hair shedding occur in an even distribution?

I'm often asked if hair shedding under normal circumstances occurs equally all over the scalp. In other words, if a person's daily shedding is 60 hairs, do 30 come from the front and 30 from the back?

Normal hair shedding

Normal hair shedding does occur equally. Hairs on the scalp grow independent of each other and so shedding occurs independent of other hairs too. If 60 hairs is a person's rate of daily shedding, then 30 would come from the front half and 30 from the back. 

Shedding in hair disorders

If a person has a hair disorder (hair loss condition), the shedding may or may not be equally distributed.  If the person has androgenetic alopecia (male balding and female thinning), then the shedding occurs much more in the area of thinning at the front. For example, in androgenetic alopecia the rate of shedding is slightly increased and perhaps 60 hairs would be shed in the front and 30 hairs in the back half of the scalp. If the person has telogen effluvium, the shedding is equally distributed all over the scalp - but at higher rates than normal. For example, patients with telogen effluvium might experience loss of 60 hairs in the front and 60 hairs in the back. In telogen effluvium, this could even be 200 in the front and 200 in the back but the key point is that the shedding is always equal.  If the individual has alopecia areata as the reason for their hair loss, shedding may not be equal. Shedding could be as high as 300 in a small section of the scalp and just 30 in another area.

Conclusion

In general, in the absence of any hair loss condition, the shedding is the same all over the scalp.