What is the right unit of measure for hair density?

[nicolivi]

Hi all,

I am 40 and have been thinning for almost 12 years now. I've recently been exploring my range of options, and doing quite a bit of reading on the subject, but there seems to be some inconsistency on the way different clinics talk about hair density, stating it in:

- "Hairs / follicles per square cm"

- "Follicular Units per square cm"

- "Grafts per square cm"

If I understand correctly, there can be many follicular units (FUs) in a graft, and there can be 1 to 4 hairs (follicles) in an FU. If this is the case, then the only representative ("truthful") measure of hair density above is "hairs / follicles per square cm", as the other two can be very misleading in terms of hair count over a fixed area. For example, you may transplant more grafts or FUs for one patient over another, but fewer hair follicles if the follicle count per graft / FU is smaller. 

If the above is correct, a more practical concern for me is if I should trust clinics that use the two latter measures, avoiding to clearly state exactly how many hairs they will aim to place on each cm of my head? I know it sounds like a small thing, but for me it undermines trust on their motivations or / and their ability to do basic math, which are not strong indicators of ethics and competence. 

Any thoughts?

Nico

[Ccd99]

My understanding is that 1 graft = 1 FU = 1 hair follicle = 1 follicular unit, and 1 hair follicle can consist of a single hair, double hair, triple hair, or in some cases even more (4,5,6,7 hairs).

Doctors will often refer to density as the number of FU's per square cm (FU/cm^2). But this does not always equate to true visual density as some people have finer hair, some have thicker hair, and some may have more hairs in a FU, and some may have less. For example someone with a density of 50 FU/cm^2 but all consisting of single hairs will visually probably look similar to someone with 25 FU/cm^2 but consisting only of double hairs (that is assuming they both have the same hair thickness).

That's why some people that have great hair characteristics will get away with implanting less grafts compared to others.

By the way there is also something called the "hair coverage value" (Google for more info) which can be calculated to figure out visual density. But I don't think all doctors use this, those that do are probably more mathematically inclined (which IMO is a good thing).

Edited November 30, 2023 by Ccd99

[jjalay]

Its more of an artistry and less mathematics as you think. Most of the experienced doctors will work with magnification and under the loop if they see a gap where they can put another grafts, this will be done to improve the density.

[Melvin- Admin]

Hairs per cm2, the number of grafts also matters. But what’s probably just as important is the thickness of the hair shaft. 

[Nw7HPE]

Grafts per Cm2