Children are naughty by nature and run after each other all day, so fractures are not uncommon. At the age of ten or so, the bones should have been like willow branches in spring, which are not easily broken completely. On the contrary, there is a little girl, about 10 years old, who is just at the age of chasing and competing with her classmates on the sports field. But somehow, its bones are like delicate porcelain, a touch will break. Classmates avoided walking with him. After going to the hospital, he was diagnosed with osteoporosis after X-ray examination and blood tests. The doctor said that his bones were like sesame seeds, which were easily broken. The world is full of strange diseases! Young men with hypogonadism have significantly lower levels of androgens and lower bone density than normal people. Although their bones are not as fragile as Xiao Gang’s, their chances of fracture are more than ten times higher than those of normal people of the same age. If the androgen level is replenished to normal level before the epiphysis closes, the BMD value increases significantly; in middle-aged and older men, as the androgen level decreases, it is accompanied by a decrease in BMD value. Compared to younger men, older men are more prone to fractures, and according to the World Health Organization, fractures have become the sixth leading cause of death in older men. These facts indicate that androgens are an important factor in the hardness of male bones, and that osteoporosis has become a common cause of serious effects on the quality of life of older men. How do androgens affect bone density? Although bone is hard as a rock, it is a living tissue. Beneath its hard exterior lies a roaring activity of demolition and construction. First, osteoclasts dig out the old bone, and then osteoblasts produce new bone to replace it. This is the metabolism of the bone. There are androgen receptors on the membranes of osteoblasts in the bones, and through the receptors androgens stimulate the activity of osteoblasts. Before puberty begins, the epiphysis is not yet closed, and as androgen levels continue to rise, the construction of bone is greater than its destruction, so the density of bone increases; at sexual maturity, androgen levels reach their peak, and the density of bone reaches its lifetime peak. The epiphysis closes at this time. Later, as we grow older, androgen levels slowly decline, the activity of osteoblasts decreases, and the activity of osteoclasts increases, so the destruction of bone is greater than its construction, and the density of bone gradually decreases and becomes lax. In fact, the real influence on bone density is estrogen, which is converted from androgens in men. However, androgen deficiency in men, whether it is hypogonadism or decreased androgen levels in older men, will lead to a decrease in estrogen levels and eventually cause osteoporosis. In addition to reduced androgen levels, there are other causes involved in declining bone density in middle and older age. Weakened muscle strength, reduced physical exercise, and poor lifestyle habits such as long-term smoking, alcohol abuse, and coffee addiction can all aggravate the occurrence of osteoporosis. Some diseases that affect the deposition of calcium salts and the absorption of fat-soluble vitamins and their effects, such as chronic diarrhea and partial diet, are also common causes of osteoporosis