WASHINGTON — More than half of North American women receiving treatment for osteoporosis have suboptimal serum vitamin D levels, Anne E. de Papp, M.D., and her associates reported in a poster at the annual meeting of the American Association of Clinical Endocrinologists.
Inadequate vitamin D concentrations can lead to alterations in calcium and phosphate homeostasis, secondary hypoparathyroidism, bone loss, osteoporosis, and an increased fracture risk.
Yet, data from a cross-sectional study of 1,536 postmenopausal women seen at 61 North American sites suggest that the problem is often overlooked in patients being treated for osteoporosis, said Dr. de Papp, of Merck & Co. Inc., West Point, Pa., and her associates.
The patients had a mean age of 71 years (range, 47–103 years) and a mean BMI of 26.4 kg/m
Vitamin D supplementation at a dosage of 400 IU/day or more was reported by 59.5% of the women, while the rest were taking less.
For the entire group, the mean serum level of the active vitamin D metabolite 25-hydroxyvitamin D was 30.4 ng/mL. Most of the women (52%) had levels below 30 ng/mL, considered the minimum concentration necessary to maintain optimal serum parathyroid hormone levels (Osteoporos. Int. 1997;7:439–43), while 36% had 25-hydroxyvitamin D levels below 25 ng/mL, and 18% were below 20 ng/mL.
Suboptimal 25-hydroxyvitamin D concentrations were found in 63% of women taking less than 400 IU/day of vitamin D, compared with 45% of those receiving 400 IU or more per day. Other significant risk factors for vitamin D inadequacy were having less than a 12th grade education, no discussion about vitamin D supplementation with a physician, lack of exercise, concomitant medication use, BMI of 30 or higher, nonwhite race, and age over 80 years.
The study was funded by Merck.