維他命D值低會促成壓力型骨折風險


  【24drs.com】根據發表於二月號足踝外科期刊的一篇回溯世代研究,至少有半數壓力型骨折患者的維他命D值不足。
  
  第一作者、賓州馬爾文Premier骨科與運動醫學的Jason R Miller醫師等人寫道,一個人的維他命D濃度,與飲食鈣及磷的攝取密切相關。
  
  他們指出,維他命D缺乏者僅吸收約10%至15%的飲食鈣質和50%至60%的飲食磷,因此,可能會發生骨質降低與結構完整性不足,以及鈣數值降低。
  
  不過,作者們表示,他們的研究對象、體適能良好、有運動者中,維他命D不足的閾值各異;對於功能需求增加者,無法定義一個可以保證適當骨骼健康的最低血清25-hydroxyvitamin D [25(OH)D]值。
  
  我們希望,多多討論「對於可能有壓力型骨折風險的活動型患者,建議維持比較高之正常血清維他命D值」的可能性。
  
  相對於常見的運動傷害,壓力型骨折發生於施諸骨骼的壓力超過它承受這些壓力的能力時。
  
  研究者回溯回顧了2011年7月至2014年8月間在Miller醫師的診所確認有壓力型骨折之患者的病歷,獨立審查確認有壓力型骨折診斷的124名患者的X光片和/或磁振造影資料。
  
  有53名患者在他們的骨折診斷前3個月內有測量維他命D值,平均血清25(OH)D值為31.1 ng/mL,其中,44名患者(83%)的數值低於40 ng/mL,根據維他命D委員會的標準認定為不足。約半數、28名患者(52.8%)的數值低於30 ng/mL,根據美國內分泌協會的建議認定為不足。
  
  約三分之一(33.9%)患者的第二腳骨(蹠骨)有壓力型骨折,這是壓力型骨折最常見的類型,另17.7%患者在第三蹠骨發生。
  
  作者們指出,血清25(OH)D值和發生壓力型骨折之間的關聯,在之前一些已發表的研究中曾提出,已經進行廣泛的研究,在年輕而活躍的新兵中曾有報告。
  
  他們建議,血清維他命D值至少達40 ng/mL,以預防壓力型骨折,特別是需要中度或高度功能需求的活動型患者。
  
  因為17%患者的數值至少有40 ng/mL,作者們說明了壓力型骨折其他的一些風險因素,如之前定義的,包括白種人、女性、尼古丁與酒精濫用、使用類固醇、骨密度低、身體質量指數低、使用雙磷酸鹽類藥物治療。
  
  當有維他命D不足或缺乏且發生壓力型骨折時,研究者建議,主要可根據內分泌協會維他命D缺乏患者的指引進行補充。
  
  他們寫道,對於25(OH)D值<35 ng/mL者,我們會建議高劑量補充,導入4至8週的處方,每週劑量50,000 IU,直到骨折癒合;對於血清濃度35 -40 ng/mL者,我們建議每天3000- 5000 IU。
  
  他們結論指出,維他命D值達到適當程度之後,患者可以服用至少每天2000 IU的維持劑量。
  
  資料來源:http://www.24drs.com/
  
  Native link:Low Vitamin D Levels May Contribute to Stress Fracture Risk

Low Vitamin D Levels May Contribute to Stress Fracture Risk

By Tara Haelle
Medscape Medical News

At least half of patients with stress fractures who had their vitamin D levels tested had insufficient levels, according to a retrospective cohort study published in the January–February issue of the Journal of Foot & Ankle Surgery.

"An individual's vitamin D concentration is intimately linked to the absorption of dietary calcium and phosphorus," write lead author Jason R Miller, DPM, of Premier Orthopedics and Sports Medicine in Malvern, Pennsylvania, and colleagues.

They note that individuals with vitamin D deficiency only absorb approximately 10% to 15% of dietary calcium and 50% to 60% of dietary phosphorus, "thus, a decrease in bone mineralization and structural integrity can develop," with a decrease in calcium levels.

The authors also say, however, that the varying thresholds for vitamin D insufficiency are estimates among the type of patients they studied — fit, active individuals. "No minimum serum 25-hydroxyvitamin D [25(OH)D] level has been defined that can guarantee adequate skeletal health in a patient with an increased functional demand," they note.

Nevertheless, "we wish to encourage a discussion of the possibility that a higher 'norm' concentration of serum vitamin D should be recommended for active patients who may be at risk of stress fractures."

Study Confirms Previous Findings

Stress fractures, a relatively common sports-related injury, occur when stress on a bone exceeds its capacity to withstand those forces.

The researchers retrospectively reviewed the medical records of patients with confirmed stress fractures seen in Dr Miller's practice from July 2011 through August 2014. Independent review of radiographs and/or magnetic resonance imaging confirmed the stress fracture diagnosis in 124 patients.

The 53 patients who had their vitamin D levels measured within 3 months of their fracture diagnosis had an average serum 25(OH)D level of 31.1 ng/mL. Of these, 44 patients (83%) had levels below 40 ng/mL, considered insufficient based on standards of the Vitamin D Council. And about half, 28 patients (52.8%), had levels below 30 ng/mL, considered insufficient based on recommendations by the US Endocrine Society.

About a third (33.9%) of patients had a stress fracture in the second foot bone (metatarsal), the most common bone seen with a stress fracture, and 17.7% had one in the third metatarsal.

"The association between serum 25(OH)D levels and the occurrence of stress fractures has been previously documented in published studies, extensive investigation has been performed, and association has been reported in young and active military recruits," the authors note.

They recommend minimum serum vitamin D levels of at least 40 ng/mL to prevent stress fractures, "especially for active patients with a moderate or high functional demand."

Because 17% of patients had levels of at least 40 ng/mL, the authors describe other risk factors for stress fractures, also previously identified, including white race, female gender, nicotine and alcohol abuse, steroid use, low bone density, low body mass index, and bisphosphonate therapy.

Supplement When Vitamin D Sufficiency Accompanies Stress Fracture

When vitamin D insufficiency or deficiency exists alongside a stress fracture, the researchers recommend supplementation based largely on the Endocrine Society's guidelines for vitamin D deficient patients.

"We would advocate high dosage supplementation for individuals with a 25(OH)D of <35 ng/mL, introducing a 4- to 8-week regimen of a 50,000 IU weekly dose until fracture healing has occurred," they write.

"For those with a serum concentration of 35 to 40 ng/mL, we would recommend 3000 to 5000 IU daily."

After vitamin D levels are adequate, patients can take a maintenance dose of at least 2000 IU daily, they conclude.

No external funding or disclosures were reported.

J Foot Ankle Surg . 2016;55:117-120.

    
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