If male pattern baldness is caused by testosterone, why are hairs on top of the head more affected by it and hairs like eyebrows, beard, inside ears etc, are affected less?
In: Biology
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Because hair follicles are different! It’s super obvious comparing beard hairs, arm and leg hairs, even pubic hairs to head hairs. However, hairs on the head are also slightly different. The one up top are more susceptible to DHT, the “high-power version” of testosterone, that people make a little later in life.
Now, if you wanna know WHY? No clue. Bodies are weird.
Well here’s something to think about: if a balding mans testies were removed, the hair on his head would grow back normally again and all his body hair would fall out. Weird right?
That’s the million dollar question I’m afraid. There are tons of theories about this paradox, but non that have answered why it happens like that.
Honestly because they are seems to be the prevailing consensus. My hair is thinning and shedding and it sucks and the best research I could find is just that. As some other people said, transitioning is definetly one way to cure it if you are thinking you were always female anyway but otherwise just trying to mitigate it or move the less sensitive hairs to the bald areas seems to be the only way to go.
There are a number of factors. Scalp tightness is an overlooked factor in my opinion. Hair tends to fall out moreso at tighter areas of the scalp, especially if there are protruding ridges in the skull.
Everyone learns in school that testosterone is the “male” hormone, and estrogen is the “female” one. Trouble is, while that’s not wrong, it’s also not completely accurate.
It’s true that testosterone is the main precursor hormone that men produce. But many of the stereotypical effects of testosterone (body hair, hair loss, libido, aggression) are actually controlled more by the hormones your body makes FROM testosterone.
Sex drive, for example, is actually significantly driven by estrogen! Your body uses an enzyme called aromatase to convert a certain amount of testosterone to estrogen. This is why bodybuilders who inject synthetic testosterone far above their natural levels end up growing breasts, unless they actively take anti-estrogen drugs. In most guys the ratio is 20-30 to 1, but if that ratio is too high OR too low, then your sex drive, erections, etc. will not function correctly.
Another hormone your body generates from testosterone is dihydrogentestosterone (DHT), which it creates with an enzyme called 5-alpha reductase. DHT is actually responsible for both body/facial hair growth, and male pattern baldness. (It also has a very high influence on sex drive.)
Now it starts to get a little more complicated. The various parts of your body have different genetic sensitivities to these hormones. Every organ in your body has hormone receptors, basically sites that “listen” for the hormone in your blood. Some people have more or less listeners on various parts of their body than others. People with less listeners need more of the hormone to trigger a reaction, and people with more listeners need less.
DHT is primarily responsible for causing facial and body hair, but DHT is actually toxic to the hair follicles on the top of your head. The follicles are just built differently. The effect is cumulative, meaning it builds up over the years and starts eventually permanently killing the head follicles. How long until you start losing it? Well, that depends on how much DHT you produce, how sensitive your follicles are to it, and how long it’s been building up. That’s why men tend to lose it later in life. It’s also responsible for the cliche of men growing hair in unexpected places as they get older.
Women don’t lose their hair because they don’t make enough testosterone to start any of this process to begin with. But some guys with very high testosterone still never lose their hair, either because they don’t generate much DHT from it, or their hair follicles don’t have many listeners and are not genetically as sensitive to it. Some guys with relatively low testosterone do end up losing their hair, either because they produce a lot of DHT, or their head follicles have a lot of listeners and are very sensitive to it.
So now, you can see how it’s actually much more complicated than what you were taught in school! Yes, you first need to produce enough testosterone, period. But then your genetics determine how much of that is converted to estrogen or DHT. And then your genetics also determines which parts of your body are the most sensitive to them. These separately controlled genetic combinations are why men are so varied, and why a simple test of testosterone levels in your blood doesn’t actually tell you very much.
But it’s also why associating certain “mainly” traits with “high testosterone” is actually not completely accurate. It’s just complicated to explain all the rest, so schools tend to teach the dumbed-down version instead.
[What really causes baldness, and it’s not testosterone – not directly.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982925/)
After working for years in laser hair removal and studying how to get rid of hair and also how to grow more hair, I’ve learned one thing.
It’s just how it works. Use the tools.
I’m sure there’s an excellent, complicated, explanation but it just is what it is. It’s the way the hair follicles respond to hormones. The hair on the top of your head is different from the hair on your arms. It’s different from the hair on your back. It’s different from pubic hair. Hair on the upper lip is a pain in the butt for everyone. Hardest area to treat for removal, man or woman.
All areas respond differently. I grew chest hair in my late 20’s then lost it again. All the hair fell out on my legs at some point. My eyebrows are getting dangerously towards Thufir Hawat level. My hairline receded then stopped. Suddenly, my beard is heavier than it ever was which is really irritating. My pubic hair is advancing towards the enemy.
Biologically, it’s simply the type of hair follicle. They are all different in how they react to hormone levels.
My brother found that sub-therapeutic Propecia works for him for thinning. He was getting thin up top, and it magically worked. It did change his hair color a bit but now he’s got a fine crop of hair again with a new hairline.
My uncle, who started shaving every day at 13 was almost bald by 20 but has a beard that would rival Father Christmas now in his 70’s. Also, completely bald on his legs and arms. My grandpa, his father, kept a full head of hair. When he died in his 90’s, the only bald spot was his military crew cut that he had since WW!!. He always kept a proper one.
Hair is weird. You treat it as you see it. Once you’re used to it, you know what to do. It does take a lot of training and practical experience.
Watch the Joe rogan podcast with Andrew huberman he goes into detail about all these hormones
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