Use of calcium supplementation is commonly discussed regarding the side effects of androgen deprivation therapy (ADT). ADT and menopause share the phenomenon of accelerated calcium loss from bones. Numerous studies demonstrate that men who are placed on ADT lose from 2-4% of the calcium in their spine during the first year of therapy. Because of this, and the general phenomenon of low vitamin D levels in all of us who use sunscreens more regularly, we recommend that men take vitamin D and calcium supplements when we start ADT.
The results of calcium loss are an increase in the risk of fracture. For example, in a study published in 2007 on 8577 men with prostate cancer who had similar fracture rates prior to treatment, the use of ADT increased the fracture rate from 14.6% to 18.7% over a 36 month observation period. Critiques of these kinds of studies abound. For example, the men who received ADT had more metastases and poorer health in general. Beyond that, in my patients, there is nothing close to 15% of men whom I follow for 3 years who have clinical fractures. How are these determined? Many times it is due to the increase in bone scans and x-rays which may pick up clinically insignificant fractures. Nevertheless, the fact that women in menopause and men after drug-induced andropause have increased calcium loss and fractures is well-established. It is also true that pharmaceutical companies have come up with effective drugs to combat this phenomenon – notably bisphosphonates (like zoledronic acid) and antibodies (like denosumab). An example in men on leuprolide can be found here. In all of these kinds of studies, the placebo/control groups were given calcium and vitamin D.
A mild controversy in this arena arose when publications pointed out an apparent increase in myocardial infarction in patients receiving calcium supplements. In one such study, evaluation of 5 trials in which calcium and vitamin D supplements were randomly assigned to >8000 patients, there were 143 patients with myocardial infarction among calcium users compared to 111 in those on placebo. This has given rise to the concerns expressed by some patients about the safety of calcium and vitamin D supplementation.
Although I am no expert in this area, there clearly are 100’s if not 1000’s of people who are (or who think they are). Ask them or read all of the literature (and DON’T miss clicking on that link…) you wish and reach your own conclusion. The recommendation for normal healthy adults is about 800IU/day of vitamin D as a supplement. You could start here if your concern is primarily about the heart attack risk. Or if you are most concerned about the fracture risk, start here. It is probably reasonable to know your 25-OH vitamin D level to be sure you aren’t deficient. 1000-2000 units of vitamin D/day seems like a reasonable supplement dose in patients who aren’t deficient. You should probably avoid calcium over-supplemntation if you have a history of kidney stones. Avoiding milk products may make sense (see this blog), so taking 1000-1500 mg calcium carbonate (chewable tums or equivalent) daily seems logical to me in patients on ADT who should probably avoid dairy products anyway.