Vitamin D insufficiency and teriparatide
J Clin Endocrinol Metab. 2007 Oct 2; [Epub ahead of print]. Response to Teriparatide in Patients with Baseline 25-Hydroxyvitamin D Insufficiency or Sufficiency, Dawson-Hughes B, Chen P. Krege JH. PMID: 1791178. When individuals are prescribed bisphosphonates for osteoporosis, vitamin D and calcium supplements are also prescribed, and felt to be an important adjunct to successful therapy. This would particularly be true for patients who are found to have serum vitamin D levels below normal. It is not known how individuals who start treatment with normal or below normal serum vitamin D levels will respond to teriparatide (Forteo) therapy, which has been shown to be very effective in treating osteoporosis and preventing fractures. See this Update for an overall picture of teriparatide's effectiveness and see this Update showing a study involving only men.
In this Dawson-Hughs study involving only women, individuals were grouped into two categories: those having serum 25-hydroxyvitamin D (25OHD) insufficiency (>10 but </= 30 ng/ml) or 25OHD sufficiency (> 30 but </= 183 ng/ml). All women received 1000 mg calcium supplements along with 400 to 1200 IU vitamin D daily during the study, and for one month before the study began. Patients received daily injections of teriparatide of either 20 or 40 micrograms for 21 months. There were no significant differences in the main outcomes of vertebral or non-vertebral fractures, change in bone mineral density (BMD) at the lumbar spine or femoral neck or change in bone formation marker amino-terminal extension peptide of procollagen type 1, and the proportion of women with serum calcium >/= to 2.76 mmol/L 4 to 6 hours after dosing. The authors conclude: "In postmenopausal women with osteoporosis and normal intact PTH, the responses to teraparatide did not differ significantly in women with baseline 25OHD insufficiency or sufficiency."
Editor's comments: This study shows that the baseline vitamin D level is not important as long as supplements are given to increase serum 25OHD to normal levels during teriparatide therapy. Although the study only involved women, there is no reason to believe that men wouldn't have equal results. It is too bad that a third category wasn't tested: those with insufficient vitamin D and who got no supplements during therapy. It would be interesting to see how significant that would have been regarding successful therapy.
Fracture risk and prostate cancer therapy
Scientific World Journal. 2007 Sep 28; 7:1590-5, The practice of Scottish urologists in the assessment and management of fracture risk in the ageing male being treated for prostate cancer. Ngu WS, Bryne DJ. PMID: 17906821. See this Update for a review of this topic. This article by Ngu and Bryne is just another reminder that prostate cancer therapy often involves methods that reduce BMD and increase fracture risk. The treatment is done by urologists, not endocrinologists, who normally work with osteoporosis patients. The urologist's main concern is the prostate cancer, which often means the osteoporosis gets overlooked. In this Scottish study that meant that 64.1% of the prostate cancer patients got no warning they were at increased risk for osteoporosis.
Editor's comments: If you are receiving prostate cancer therapy that involves androgen deprivation or castration, you simply must ask to be referred to an osteoporosis specialist to have your BMD evaluated and to have preventive or treatment therapy for osteoporosis. Assume you have or will get osteoporosis unless proven otherwise.