Osteoporosis and Male Infertility
Introduction to the Relationship Between Male Infertility and Osteoporosis Risk
Many different factors can impact men’s bone health, including hormones, diet, exercise, and genetics. From a hormonal standpoint, adequate testosterone and estradiol levels are important for maintaining good bone strength. Low testosterone and estradiol levels are known risk factors for the weakening of bones in men, making them more susceptible to fractures as they age.
Bone strength (also called bone mineral density, or BMD) is significantly influenced by:
1) Hypogonadism (low testosterone)
2) Nutrition
3) Lifestyle (including tobacco use, alcohol use, and exercise)
4) Medications (such as glucocorticoid steroids)
5) Chronic disease
6) Heredity
Bone density is usually measured by dual energy X-ray absorptiometry (DEXA) scanning. This is a quick X-ray of the hip and spine that directly measures bone density. A T-score is then given that compares that patient’s peak bone density with normal values for his age, sex, and race. Osteoporosis is typically defined as having a T-score of -2.5 or lower (2.5 standard deviations or more below the mean), and it puts men at risk for greater odds of developing a fracture, especially in the spine, proximal femur (hip), and distal radius (wrist). Osteopenia, a lesser degree of bone weakening, is usually defined as having a T-score between -1.0 and -2.5.
Men who have a low total testosterone (less than 300 ng/dL) are generally advised to follow osteoporosis prevention guidelines in order to prevent worsening of bone mineral density. Some clinicians suggest that men with a very low total testosterone (less than 200 ng/dL) have a baseline DEXA scan to see if osteoporosis or osteopenia is already present. If the DEXA scan is abnormal, then it should be repeated in two years to see if the recommended interventions have been effective.
General guidelines for the prevention of osteoporosis and osteopenia
1) Calcium 1,000–1,500 mg daily
2) Vitamin D 800 IU daily
3) Regular weight-bearing exercise: three to five sessions (20 to 25 minutes each) each week of exercise, such as jogging or
running, skiing, weightlifting, or most ball sports
4) Weight loss if overweight or obese (to bring BMI down to under 25)
5) Avoid tobacco products and excessive alcohol intake
6) Correction of low testosterone levels
If these measures are not effective in reversing osteoporotic/osteopenic changes, then stronger medications (such as bisphosphonates) are available that can increase bone strength. Special diagnostic tests, such as the Fracture Risk Assessment (FRAX) tool, developed by the World Health Organization, can be utilized to see if these stronger medications may be clinically indicated. Bisphosphonates work by inhibiting the normal bodily process of bone breakdown; medications in this category come in both oral forms, including alendronate (Fosamax) and risendronate (Actonel), and intravenous forms, including zolendronic acid (Zometa) and pamidronate (Aredia).
Estradiol Levels and Osteoporosis
In addition to testosterone, adequate estradiol levels also play a very important role in maintaining bone strength in men. Most experts believe that for adequate bone health, men should try to maintain long-term estradiol levels of at least 20 pg/mL if possible. Some men taking aromatase inhibitors (such as anastrazole) can have estradiol levels that fall below this range. These men should follow the basic osteoporosis guidelines listed above, consider periodic DEXA scanning if on aromatase inhibitors for a prolonged time, and stop taking them when they are done with their fertility efforts.
Clomiphene and Osteoporosis
The relationship between clomiphene and osteoporosis is still unclear. On one hand, clomiphene can increase both testosterone and estradiol levels, which should enhance bone health. However, the variable impact of clomiphene on different sets of estrogen receptors throughout the body raises concerns as to whether this medication can actually worsen osteoporosis over time. Studies have shown conflicting results, with some showing improvements in bone density and others showing decreased bone density in men using clomiphene. Because of these concerns, men who are done with their fertility efforts should stop taking clomiphene. If they are taking the medication for a prolonged period of time, they should consider periodic DEXA scanning.