How often should vitamin D levels be evaluated?
1. The Endocrine Practice Guidelines recommends that the screening for 25-hydroxyvitamin D levels is not necessary if the patient is receiving an adequate amount of vitamin D. However to determine whether a patient was effectively treated for vitamin D deficiency I usually recommend measurement of 25-hydroxyvitamin D 2-3 months after giving 50,000 international units of vitamin D once a week for 2 months. For those patients who are at risk for vitamin D deficiency a yearly blood level for 25-hydroxyvitamin D is reasonable. Please see Holick et. al. JCEM 2011; 96:1911-1930.
What should be done if the BMD does not increase with osteoclast inhibition?
2. Patients who receive anti-resorptive therapy often have no change or a slight decrease in their bone density. However when compared to placebo no change or the slight decrease is still better than the decrease seen without anti-resorptive therapy. Furthermore changes of BMD of at least 5% are considered to be statistically significant changes. Therefore I don't expect to see a significant increase or decrease after one year of therapy. However anti-resorptive therapy has been shown to be effective in reducing risk of fractures. To maximize the anti-resorptive therapeutic effect on bone health I make sure that my patients are receiving an adequate amount of calcium and vitamin D. For patients who are on an anti-resorptive medication and having fractures it may be reasonable to switch them to teriparatide which is the only FDA approved drug to stimulate new bone formation.
What is the risk of osteonecrosis of the jaw with osteoclast inhibitors dosed for postmenopausal osteoporosis?
3. Most of the patients who have had the complication of osteonecrosis of the jaw are cancer patients who have received multiple intravenous doses of bisphosphonate along with chemotherapy and radiation therapy. The incidence of osteonecrosis of the jaw in postmenopausal women on bisphosphonate is extremely rare.
If my oncology practice is not set up to manage bone health, should the primary care doctor or an endocrinologist be consulted?
4. I recommend that patients with cancer receive adequate amount of calcium and vitamin D to maximize their bone health. If a patient is at risk for osteoporosis and a bone mineral density study reveals osteoporosis or osteopenia it is reasonable to have that patient be seen by their primary care physician or an endocrinologist to work them up for secondary causes and recommend appropriate therapy.
What are the risks of increasing cardiac calcifications with calcium supplements and is this clinically significant?
5. Based on all of the literature there is little evidence that patients who take the IOM recommended amount of calcium from dietary sources and supplements, which is 1000 mg for adults up to the age of 50 years and to 1200 mg for adults over the age of 50 years, will increase their risk for cardiovascular calcification.
What are the risks of nephrolithiasis with supplements?
6. The IOM and Endocrine Practice Guidelines states that there is no increased risk for developing kidney stones when increasing vitamin D and calcium intake to the levels recommended. In the general population an increase in calcium intake reduces risk for nephrolithiasis because the calcium binds the oxalate which is the major cause for kidney stone development. These patients have hyper absorption of oxalate and oxalaturia. For patients with a history of kidney stones I have them take calcium in the form of calcium citrate with meals and adequate vitamin D to help maintain their bone health and reduce risk for additional stone formation.