Vitamin D Often Overlooked When Treating Osteoporosis

Peggy Peck

October 05, 2004

Oct. 5, 2004 (Seattle) -- New research suggests that vitamin D intake is an often overlooked factor in bone health, even in women who are being treated for osteoporosis, according to two studies reported here at the 26th annual meeting of the American Society for Bone and Mineral Research (ASBMR).

In one study, Michael Holick, MD, PhD, reported that of 1,536 osteoporotic women treated at 61 clinical centers, 62.5% were receiving less than 400 IU of vitamin D, which is the current recommendation for daily supplementation.

Dr. Holick, who is a professor of medicine, dermatology and physiology at Boston University in Massachusetts, said, "This is the first study that actually looked at women who are being treated with prescription drugs for osteoporosis. What we see is that these women are not getting enough vitamin D."

The mean age of the women was 71 years, and 92% were white. The majority were community-dwelling women who were seen in primary care practices. The women were asked to complete survey questionnaires to assess knowledge of vitamin D and use of vitamin D supplements as well as fall and fracture history. In additionally, serum 25(OH)D and biointact parathyroid hormone (both using the Nichols Advantage System) and blood chemistry panel were obtained.

Dr. Holick said that the questionnaire found that "about 59% of women reported that their physicians have never discussed vitamin D supplementation with them."

Study coauthor Anne de Papp, MD, said that because the data come from questionnaires it is possible the treating physicians did discuss vitamin D with the women but the women did not recall what physicians said.

"The big difference between this and other studies," said Dr. de Papp, "is that previous studies looked at the epidemiology of vitamin D deficiency whereas here we actually measured vitamin D levels in women who were being treated for osteoporosis and whom one would think would be more closely watched by their physicians." "I think the doctors didn't talk about [vitamin D]," Dr. Holick told Medscape. "Primary care physicians are terribly busy and they have forgotten that you need vitamin D and calcium along with the bisphosphonates."

He added that 18.7% of the women reported a low trauma fracture since age 45 years, and 18.5% reported a fall resulting in a fracture within the past five years.

The mean (SD) serum 25(OH)D was 30.4 (13.2) ng/mL and the median was 29 ng/mL (range, 7-212 ng/mL). Slightly more than 1% of subjects had 25(OH)D levels less than 9 ng/mL, 8.1% has levels less than 15 ng/mL, 18% had levels less than 20 ng/mL, 36% were less than 25 ng/mL, and 52% had serum 25(OH)D levels less than 30 ng/mL. Moreover, 16.5% of the women had evidence of secondary hyperparathyroidism as defined by normal serum calcium and elevated parathyroid hormone levels.

As might be expected, the prevalence of vitamin D insufficiency, defined as 25(OH)D less than 25 ng/mL, was significantly higher in women whose intake was less than 400 IU of vitamin D daily.

The study was funded by Merck & Co., Inc., and coauthor Dr. de Papp is director of clinical development for U.S. Human Health at Merck.

The findings were no surprise to Clifford Rosen, MD, a past president of the ASBMR and director of the Maine Center for Osteoporosis Research in Bangor. "We see this all the time," Dr. Rosen told Medscape. "It is a function of lack of sunshine and lack of supplementation."

He noted that aside from milk and orange juice there are few places to get vitamin D other than from 15 minutes of direct sun exposure or from supplements. Sun exposure is compromised by sunscreen and glass, so getting sun through the window does not help. "This is a big deal," Dr. Rosen said. "At least half the patients with hip fractures that we see are vitamin D deficient. We don't stress enough the idea of taking vitamin D supplements along with bisphosphonates."

A second study pointed out that while vitamin D deficiency contributes to morbidity in patients with osteoporosis, even healthy individuals can suffer consequences from too little vitamin D.

Paraskevi Sapountzi, MD, a research fellow in endocrinology at Loyola University Medical Center in Maywood, Illinois, found that people with vitamin D deficiency who did not have osteoporosis had a diminished quality of life. In the study, 24 women and five men with vitamin D levels less than 20 ng/mL completed a quality-of-life questionnaire designed by the International Osteoporosis Foundation.

"We observed that patients with lower levels of vitamin D did worse in the domains of social activities and mobility on the standard Qualeffo-41 questionnaire," Dr. Sapountzi said at her poster presentation. However, she did not see a correlation between quality-of-life scores and osteoporosis severity. "This study suggests that people who are deficient in vitamin D have aches and pains that impact on their activities of daily living, and that impact is independent of their osteoporosis level," Dr. Sapountzi said.

Dr. Holick agreed with Dr. Sapountzi's conclusion. "The number of potential diseases related to vitamin D deficiency is quite remarkable," he said. In addition to the osteomalacia noted by Dr. Sapountzi, he said studies indicate that vitamin D deficiency is associated with diabetes; multiple sclerosis; rheumatoid arthritis; colon, prostate, and breast cancer; and high blood pressure. "We estimate that 40% to 60% of fibroneuralgia is related to vitamin D deficiency," he said.

Dr. Holick added that while the current standard of 400 IU of vitamin D a day is "a step in the right direction, I would recommend that both children and adults get about 1,000 IU a day."

ASBMR 26th Annual Meeting: Abstracts SU581 and SU583. Presented Oct. 3, 2004.

Reviewed by Gary D. Vogin, MD

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