What is Osteosclerosis? - Definition & Causes

Instructor: Artem Cheprasov
Is strong bone a good thing? To an extent. Sometimes, it can be too strong as per osteosclerosis. Let's find out what this is and learn about some of its causes.


You've almost certainly heard of a famous term, atherosclerosis. What does this refer to? In part, the hardening of the arteries. The '-sclerosis', in atherosclerosis, actually refers to the abnormal hardening of something. This same suffix can be found in osteosclerosis, where 'osteo-' refers to bone. You can now define osteosclerosis completely on your own. Osteosclerosis refers to the abnormal hardening of bone.

Let's expound upon that definition in this lesson and go over some of its many potential causes as well.

Detailed Definition

Osteosclerosis leads to the increased density of bone. This occurs as a result of increased bone formation or reduced bone resorption (or both).

Osteosclerosis can be the result of osteopetrosis, an inherited disorder. Did you spot the 'petro' in there? As in 'petr'ified wood, or wood that has turned to stone. In other words, osteopetrosis refers to stone-like bone.

Now, you might think that having bones as strong and hard as stone is a great thing. But think again.

Let's go back to that petrified wood. Wood that is alive, as per a tree trunk, is pretty strong to begin with isn't it? But it's also slightly flexible. It can sway under the stress of wind, bend a bit, and spring back into shape without breaking. If you were to take a hammer and chisel to the tree trunk and gently tap at the trunk, pretty much nothing would happen.

But a petrified tree is different. Sure, it's stronger in some sense, perhaps in resisting the forces of wind, but it's also less malleable and more fragile as a result of its increased density. If you were to take a hammer and chisel to petrified wood, you'd easily crack it piece by piece or even in full, even with the gentlest of taps.

Well, bone that is alive is pretty strong, like a tree trunk. Like a living tree, it can also bend a bit without breaking. If it gets hit with something, it'll deform somewhat and spring back into shape. But if it becomes harder and more stone-like, it'll become more prone to fracture under various forms of stress.


The many different causes of osteosclerosis are too great in number to list in their entirety here, but we'll go over a few of them in some detail and then list some other ones for your reference.

Besides osteopetrosis, one potential cause of osteosclerosis is hypervitaminosis D. In other words, too much vitamin D in the body. Vitamin D helps your body absorb calcium. Hypervitaminosis D might occur when someone takes too many vitamin D supplements, especially when they are young and still maturing. This would lead to excess calcium levels in the body. The excess calcium is then, in part, deposited into the growing bone, increasing its density in the process.

Another potential cause of osteosclerosis is fluorosis. Fluorosis refers to a condition that occurs when a person ingests too many fluorides, like the same ones found in water or toothpaste. This usually occurs over a long period of time. One possible reason is drinking too much black tea, some types of which have lots of fluorides. Increased levels of fluorides in the body can stimulate bone cell proliferation, which leads to increased bone density.

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