Causes of osteoporosis could be identified in some 40-60% of men who have osteoporotic fracture. The most common are hypogonadism and glucocorticoid therapy. In addition a significant proportion of those who fracture have gastrointestinal disease, vitamin D deficiency, excessive alcohol intake or chronic anticonvulsant use. More recently transplantation has emerged as important cause of osteoporosis both in men and women.
A study addressing the determinants of bone density in older men found that age, previous fracture, gastrectomy, peptic ulcer, rheumatoid arthritis, glucocorticoid use, hypertension, previous hyperthyroidism, chronic lung disease and smoking were associated with lower bone density (BMD). Higher BMD in the same study was positively associated with weigh, moderate alcohol intake, osteoarthritis and thiazide use.
A study of healthy men over the age of 70 years indicated that measures of body composition such as weight and lean mass were the main predictors of their bone mass. Men with lower femoral neck BMD for age had significantly lower weight and lean mass whereas those with lower spine BMD for age also had significantly lower fat mass.
Overt hypogonadism has long been recognised as a cause of osteopenia or osteoporosis. Even men with a history of delayed puberty are more likely to be found to have osteopenia/osteoporosis later in life. Delayed puberty accounts for approximately 2-3% of osteoporosis in those with so called idiopathic osteoporosis. These findings support timing of puberty as an important determinant of peak bone mass which in turn is a major determinant of bone density in later life in men as it is in women.
When all possible causes are excluded almost 50% of men falls into category of so called "idiopathic osteoporosis" where cause is unknown.