Osteoporosis in men

Published on January 19, 2015   41 min
Hello, my name is Peter Ebeling, and I'm the head of the Department of Medicine in the School for Clinical Sciences at the Monash Health Translation Precinct in Victoria, Australia. My Henry Stewart talk today is about osteoporosis in men.
My potential conflicts are listed here. I receive departmental research funding from Merck, Novartis, Amgen, and Eli-Lilly, and I've received honoraria from Amgen and Merck.
Today, I'd like to discuss with you epidemiology and mechanisms of bone loss in men and the importance of estradiol. I'd like to review the Endocrine Society guidelines on osteoporosis in men. I'd like to assess risk factors for osteoporosis in men, and review osteoporosis treatments and gaps in our evidence base.
We've spent 20 years studying osteoporosis in men. And these are data from Cyrus Cooper when we were working together at the Mayo Clinic. These data show that with aging, vertebral and hip fractures increasing in men, but colles fractures do not. The number of hip fractures and vertebral fractures occurring in men are about half that occurring with aging in women. So it is an important health problem.
In fact, one third of hip fractures occur in men. The increase in men with hip fractures is due to both an increase in longevity and a later-born or secular increase. However, now we're seeing that age-related hip fracture incidence rates in many Western countries are increasing in women, but not so much in men. And the mortality rates after a hip fracture in men are about 50% higher than those in women at a rate of 37.5% in 12 months.
This slide shows the annual and projected rates in hip fractures in the United States from 2010 to 2020. I think what's striking here is that hip fractures in men will increase by 52% over that time, whereas there'll actually be a decrease of 3.5% in women. What this means is that hip fractures will increase by 12% overall to 289,000 in 2030. And much of this increase will be attributable to increases in hip fractures in men. So over the next 20 years, the rising numbers of hip fractures in men will counter balance decreasing numbers of hip fractures in women.
What are the mechanisms of bone loss in men? They're slightly different to those in women because in men, trabecular thinning is important. And it's secondary to reduced bone formation rates. Whereas women lose trabeculae due to increased bone resorption, typically after their menopause. Bone loss accelerates in men after the age of 70, and is more common with low testosterone or estradiol levels. And I'll discuss the importance of estradiol later in my talk.
Other growth factors are also important. And I think insulin-like growth factor 1 has a pivotal role. The trabecular bone loss does begin early in life, and has been associated with decreases in IGF-1. Serum IGF-1 levels were also inversely associated with fracture risk for all fractures, including hip fractures. And the population-attributable risk for IGF-1 is about 7.5% for all fractures and 23% for hip fractures from work from Sweden. Importantly, 85% of cortical bone loss occurs after the age of 50 years in men. And it's associated with decreases in both bioavailable testosterone and estradiol with an associated increase in bone remodeling rates.
In this regard, changes at the cortex of bones are very important. And some studies indicate that cortical porosity, rather than cortical thickness, are related to fractures. This slide shows the relationship between cortical porosity and vertebral fractures in men with idiopathic osteoporosis. And in this study, both trabecular marrow star volume and cortical porosity independently increased vertebral fracture risks with hazard ratios of 3.9 and 4.1. And on the slide to the right, you can see the patients with vertebral fractures had an increase in cortical porosity and decreasing in bone volume in this study.
There's also evidence for age- related increases in bone turnover. In this study, bone turnover markers were high in young men, but then decreased until the age of 50. Whereas after that time, at the age of 70, urinary deoxypyridinoline, a marker of bone resorption, increased. And increases in bone turnover markers after this age were associated with reductions in cortical thickness and volumetric bone density and also reduced trabecular thickness and trabecular numbers, indicating that the rate of bone remodeling and bone resorption, in particular, is important in elderly men and contributes to bone loss.