Osteoporosis in men: bone mineral density and a changing skeleton
Men can develop osteoporosis. The condition involves reduced bone mass, bone mineral density, or structural strength, making fractures more likely. It is more common in women, but older men also experience substantial bone loss and fractures. The difference in frequency partly reflects men's generally higher peak bone mass and slower loss with age. Men are often diagnosed later in life. Osteoporosis can remain unnoticed until a fracture occurs, because decreasing bone strength often causes no obvious symptoms. Common fracture sites include the hip, wrist, and vertebrae of the spine.
Bone is living tissue rather than a permanent mineral scaffold. Its material includes collagen, a protein framework that provides flexibility, and minerals, especially calcium phosphate, that supply hardness. Each bone combines a dense outer layer called cortical or compact bone with an inner lattice of trabecular or spongy bone. Marrow occupies spaces within that structure. The mixture of materials and architecture contributes to strength. A change in bone quality can therefore matter alongside a change in the amount of mineral measured in a particular area.
Several kinds of cells continually reshape the skeleton. Osteoclasts remove old tissue through resorption. Osteoblasts lay down a new collagen framework that then mineralizes. Osteocytes, long-lived cells within bone, help direct both processes. Their activity responds in part to the mechanical loading associated with movement. During childhood and adolescence, formation exceeds removal as bones grow. In young adults, the two processes are more closely balanced. Aging and some diseases can disrupt that balance, leaving more tissue removed than replaced and gradually reducing skeletal strength.
Men generally reach peak bone mass during their 20s. Because the starting amount is usually higher and subsequent loss slower than in women, the increase in fractures tends to begin later. Bone remodeling nevertheless continues throughout adult life, with almost the whole adult skeleton renewed over roughly a decade. Men are less likely than women to be evaluated for osteoporosis after a fracture and are also less likely to receive treatment. Men who experience a major fracture, such as a hip fracture, can have serious complications. NIAMS reports that their risk of complications and death after such fractures is higher than women's.
Hormones are one influence among several. Conditions that produce low testosterone can increase osteoporosis risk in men. The gradual decline in testosterone with ordinary aging, however, is probably not a major explanation for age-related bone loss. Other contributors include long-term use of glucocorticoid medicines, some cancer treatments, endocrine disorders, and conditions affecting nutrient absorption. Family history, body size, and age also influence risk. Slender people have less bone available to lose, while a parental history of osteoporosis or hip fracture can indicate increased susceptibility.
The weakening can become apparent through a fracture after a relatively minor fall or an ordinary movement. Vertebral fractures may cause back pain, loss of height, or a more stooped posture, although not every fracture produces an immediately obvious symptom. The condition affects people of different racial and ethnic backgrounds. Risk varies between groups, but men from all backgrounds can be affected. Physical inactivity and prolonged immobility can accelerate bone loss, while poor nutrition can contribute through inadequate calcium, vitamin D, or protein. Those factors operate across the life course.
Bone mineral density testing provides a measurement of mineral in a defined area. The most common method, central dual-energy X-ray absorptiometry, is usually abbreviated DXA or DEXA. It uses a small amount of radiation and commonly measures the hip and spine. Those locations are important because fractures there can have substantial consequences. A density measurement is one part of assessing skeletal health; age, medical history, and other fracture risk factors also enter clinical interpretation. Different score systems compare the result with different reference populations.
A T-score compares bone mineral density with that of a healthy young adult. For men aged 50 and older, it is the usual score reported. NIAMS describes a T-score of -1 to -2.5 as osteopenia, a less severe form of low bone mineral density than osteoporosis, and says a T-score less than -2.5 is usually considered to indicate osteoporosis. A Z-score instead compares the measurement with people of similar age, sex, and ethnicity. It is used for younger men, premenopausal women, and children. The same numerical measurement can consequently be expressed against an age-matched reference or a young-adult reference.
The skeleton also performs functions beyond supporting movement. It protects organs such as the brain, heart, and lungs, stores minerals, and contains the marrow that produces blood cells. Bone releases substances involved in the normal function of other organs. Its maintenance depends on interactions among cells, hormones, minerals, and physical loading. Osteoporosis develops when that living structure loses sufficient mass or quality to become fragile.
- NIAMS, Osteoporosis in Men — www.niams.nih.gov
- NIAMS, What Is Bone? — www.niams.nih.gov
- NIAMS, Osteoporosis — www.niams.nih.gov
- NIAMS, Bone Mineral Density Tests: What the Numbers Mean — www.niams.nih.gov