The Mayo Clinic characterizes thin, fragile skin as skin that easily tears or breaks. It's a common problem in older adults. As you advance in years, the layers of your skin simply thin and become more fragile. However, there are a number of other factors affecting the skin's thickness. Even disorders and medications can contribute to a thinning of the skin.
The most frequent cause of thin, fragile skin is aging. With each passing year, the surface layer of your skin thins and loses some of its elasticity. The levels of collagen and elastin diminish within the underlying layer of the skin known as the dermis, and you begin to lose fatty tissue that makes up the hypodermis, or the deep, protective layer of the skin; all of these factors lead to thinner, more fragile skin.
The Mayo Clinic also lists the sun as a contributing factor to thin, fragile skin. Ultraviolet light tends to deteriorate the collagen and elastin making up the dermal layer of the skin. As collagen and elastin levels diminish, the skin thins, making it much more fragile.
Another potential cause of thin, fragile skin is corticosteroids. Both oral and topical corticosteroids can cause the epidermis to atrophy, leading to easy bruising and tearing of the skin. Short-term use of corticosteroids doesn't pose this problem.
Ehlers-Danlos syndrome is actually a grouping of disorders that affects the production of collagen within the body, notes the Arthritis Foundation. They're genetic conditions passed from parent to child. Since collagen is an important component to healthy skin, people with this condition tend to have weaker skin than normal, which leads to easing bruising and tearing of the skin.
Amyloidosis is another grouping of disorders that leads to thin, fragile skin, according to the Mayo Clinic. Though the cause of these conditions is still unknown, the reason for the thinning of the skin is linked to the buildup of antibodies produced by bone marrow. The antibodies may also cause a thickening of the skin is some people.
Genetics can also play a role in thin, fragile skin. Much like Ehlers-Danlos syndrome, it's simply a hereditary trait passed from parent to child, which makes them predisposed to develop a thinning of the skin.