Does vitamin D supplementation in women with low levels of the vitamin affect bone mineral density, muscle mass, strength, or falls risk?
"But her vitamin D level is low! I have to treat it." No, you don't, if your patient is a typical community-dwelling postmenopausal women younger than 75 years. The usual dose of vitamin D, 800 IU (20 mcg) daily, will not increase levels even after a year of therapy and has little effect on calcium absorption or bone mineral density. A high dosage -- 50,000 IU (125 mcg) twice monthly -- will raise levels but is similarly ineffective in improving minimally low bone mineral density, muscle strength, functional status, physical activity, or risk of falls. Not checking vitamin D levels will make it easier not to (ineffectively) treat low levels. (LOE = 1b)(www.essentialevidenceplus.com)
Hansen KE, Johnson RE, Chambers KR, et al. Treatment of vitamin D insufficiency in postmenopausal women: A randomized clinical trial. JAMA Intern Med. 2015;175(10):1612-1621.
Study design: Randomized Controlled Trials
Funding source: Government
Setting: Outpatient (any)
These investigators, through community advertising, enrolled a total of 230 postmenopausal women, 90% of whom were white, with an average age of 61 years and baseline vitamin D levels of 14 ng/mL through 27 ng/mL (39 - 67 nmol/L). A "low" 25-hydroxyvitamin D level is typically less than 30 ng/mL (75 nmol/L). The women had low-normal hip T scores of bone mineral density (average -1 SD). Using typical tests of balance and lower extremity strength, the women were at low risk of falls. The women were randomized, using concealed allocation, to receive either placebo, daily vitamin D3 800 IU (20 mcg), or twice- monthly vitamin D3 50,000 IU (125 mcg). The twice-monthly, high-dose group had their vitamin D levels monitored and the dose was increased if levels did not increase to at least 30 ng/mL (75 nmol/L). After 1 year, neither vitamin D treatment regimen changed bone mineral density, muscle mass, functional status, or physical activity. The number of women reporting at least one fall—almost of half of the women—was not different among the groups. The study was only 1 year in length, which should be long enough to see changes in vitamin D levels and muscle mass though perhaps not long enough to see changes in fall rates (if there is a difference). The US Preventive Services Task Force concludes there is insufficient evidence to recommend for or against screening for vitamin deficiency; the National Institute of Health and Care Excellences recommends vitamin D supplementation in members of high-risk groups.
Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
POEMs are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, please see http://www.essentialevidenceplus.com(www.essentialevidenceplus.com).
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